Dissertations / Theses on the topic 'Aspetti genetici'

Vengono esaminati i caratteri petrografici e geologici del verde di Prato, un materiale ampiamente utilizzato nelle architetture religiose della Firenze medievale e rinascimentale. Dopo una illustrazione delle analisi svolte, si definiscono le proprietà tecniche e le fasi di alterazione del materiale in opera, e si suggeriscono gli interventi necessari per la conservazione.

The congenital thrombocytopenias are a heterogeneous group of disorders characterized by reduced number of platelets and variable clinical manifestations from severe to milder forms of incidental finding. They are divided into: 1) thrombocytopenia defect of megakaryocytic differentiation and maturation 2) MK migration defect from the bone marrow to the vascular niche 3) elongation of the pro-platelets. Then there are the hereditary thrombocytopenias from reduced platelet survival and thrombocytopenias with a still unknown pathogenesis. Currently, there are now at least 20 genes whose genetic defects determine a phenotype characterized by hereditary thrombocytopenia, but approximately 50% of patients have forms that do not coincide with any known defect. In recent years, there were several forms of hereditary thrombocytopenia associated with the development of hematologic and non-haematological malignancies that have aroused a great interest in researchers; especially the forms associated with mutations of ANKRD26, RUNX1 and ETV6. Purpose The purpose of this work is: 1. Build a comprehensive database of patients with inherited thrombocytopenia studied in our laboratory, defining the genetic mutations found. 2.Conduct a preliminary study on the presence of mutations in the 5'UTR of ANKRD26 in patients with sporadic and inherited thrombocytopenia, who did not fit into known forms of inherited thrombocytopenia and who had normal platelet volume (4μm˂MPV˂8μm), establishing the clinical and molecular features of this new form of thrombocytopenia and studying families with inherited mutations in this gene. 3. Enlarge the investigation to two other genes involved in inherited forms of thrombocytopenia with susceptibility to hematological malignancies: RUNX1 and ETV6. 4. Collect and analyze data related to the course of pregnancy in a large cohort of patients with IT forms (inherited thrombocytopenia). Materials and methods At the Medical Clinic 1 of the City Hospital-University of Padua complex there exist a series of about 70 family pedigrees of patients with inherited thrombocytopenia from hidden defect. The assessment includes the clinical history and the study of the expression of surface platelet antigens by flow cytometry method using monoclonal antibodies. To evaluate the platelets morphology, the method of staining with May-Grunwald / Giemsa (MGG) on peripheral blood (macro, micro and normo thrombocytopenia) has been adopted. The DNA was extracted from whole blood and amplified for the study of the following genes: GpIbα, GpIbβ, GPIX, MYH9, ACTN1. The products of the amplification reactions were visualized by agarose gel electrophoresis and sequenced with the Sanger method. We carried out a preliminary study on the presence of mutations in the 5'UTR of ANKRD26 in patients with sporadic and inherited thrombocytopenia, which did not fit into known forms of inherited thrombocytopenia and who had normal platelet volume (4μm˂MPV˂8μm) in order to be able to define the clinical and molecular features. We then expanded the investigation to RUNX1 and ETV6, two genes involved in hereditary forms of thrombocytopenia with predisposition to blood cancer in thrombocytopenic patients and not (MDS + thrombocytopenia; MDS thrombocytopenia -) belonging to different classes of myelodysplastic syndrome sec. WHO 2008. Finally, as part of thrombocytopenia family confirmed through genetic investigation, we participated in Pregnancy In Inherited Platelet Abnormalities (PIPA), multicenter retrospective evaluation of 339 pregnancies in 181 women with 13 different forms of thrombocytopenia. Results 8 families (12%) have mutations in the MYH9, MYH9-related disease, 12 families (19%) have mutations GP1Bα, 4 families (6%) have gene mutations that cause GP1Bβ Bernard-Soulier Syndrome (BSS) mono or biallelic. The remaining families (60%) do not have the genetic mutations in the studied glycoproteins, and no mutation in the ACTN1 gene. In light of recent studies on the forms of inherited thrombocytopenia characterized in our laboratory, we conducted a preliminary study on the presence of mutations in the 5'UTR of ANKRD26 in patients with sporadic and inherited thrombocytopenia, which did not fit into known forms of inherited thrombocytopenia and showed normal platelet volume (4μm˂MPV˂8μm). We identified two different heterozygous mutations, located in the 5'UTR untranslated region of the gene. Given the interest in the study of hereditary thrombocytopenia associated with the development of hematologic and non-hematological malignancies, in particular of RUNX1 and ETV6 genes, responsible for non-syndromic autosomal dominant thrombocytopenia, we collected preliminarily a small series of myelodysplastic thrombocytopenic subjects (9 subjects), myelodysplastic subjects with platelet counts within the normal range (12 subjects) and 27 control subjects with hereditary undetermined thrombocytopenia; this in order to strengthen the evidence about a possible association between mutations in the mentioned genes, thrombocytopenia and risk myelodysplastic / leukemia evolution. Of these subjects, we collected data on age, sex, karyotype, number of blast cells, hemoglobin and platelets. Preliminary data (Table 1) show that mutations of RUNX1 ETV6 gene are present only in the group of myelodysplastic thrombocytopenic. GENE POSITION MUTATION RUNX-1 EXON 4 c.76C>G RUNX-1 EXON 8 c.934del A RUNX-1 EXON 9 c.1214_1215insTG ETV6 INTRON 1 c.28+192delC Table 1. Mutations found in RUNX1 and ETV6 genes Although the involvement of these genes in thrombopoiesis is known, the exact mechanism responsible for thrombocytopenia is not yet clear. The rarity of these diseases makes it difficult to collect relevant data for analysis of genotype-phenotype relation. In the multicenter study (PIPA) we have classified 23 pregnancies (13 women): 5 women have BBSs, mBSS 3, 4 MYH9-RD, 1 ANKRD26. The average age at diagnosis of thrombocytopenia is 30 years, the average platelet count before giving birth is about 60 x 109 platelets / L, even if in some cases there was a drastic reduction in platelet aggregation. The bleeding tendency is low before birth and only in two pregnancies platelet transfusion is needed. All births took place between the 34th and 40th week; 13 are born by caesarean section and 10 vaginally. Only 9 infants carry the same disease of the mother, although in 6 cases the data is not available because they were not made inquiries about it. We found only one case of neonatal death due to brain hemorrhage, but no cases of bleeding in newborns. Conclusions The thrombocytopenia is the most common disorder of hemostasis and is a heterogeneous group of clinical entities. The peculiarity of family forms is the difficulty of clinical identification since they are often classified as immune thrombocytopenia and patients undergoing inappropriate therapy. As reported in the results of recent studies involving a higher number of families, in our work the most common forms of thrombocytopenias family is the BSS, the MYH9-RD followed by ANKRD26. Thanks to a careful analysis of clinical and genetic investigations associated with recent molecular studies, it is now possible to identify and correctly classify patients with new genetic mutations even though more than 50% of families remain with no diagnosis. To evaluate the possible mechanisms involved in the development of thrombocytopenia being myelodysplastic syndromes will be essential to study extensively the three categories of patients: thrombocytopenia hereditary with defect of ANKRD26, RUNX-1 and ETV6, myelodysplasia or leukemia with prevailing thrombocytopenia. A larger number of cases of these subjects will allow us to deepen the study of functional mutations defining the clinical and molecular features, in order to evaluate a possible link between myelodysplasia and thrombocytopenia and understand at what level of megakaryopoiesis and hematopoiesis they intervene
Le piastrinopenie congenite sono un eterogeneo gruppo di patologie caratterizzato da ridotto numero di piastrine e si presentano con manifestazioni cliniche variabili da forme gravi a forme più lievi di riscontro casuale. Si suddividono in piastrinopenie da difetto della differenziazione e maturazione megacariocitaria, difetto di migrazione dei MK dalla nicchia ossea del midollo a quella vascolare e della elongazione delle pro-piastrine. Vi sono poi le piastrinopenie ereditarie da ridotta sopravvivenza piastrinica e le piastrinopenie a patogenesi ancora sconosciuta. Attualmente si conoscono almeno 20 geni i cui difetti genetici determinano un fenotipo caratterizzato da trombocitopenia ereditaria, ma circa il 50% dei pazienti hanno forme che non coincidono con nessun difetto noto. Negli ultimi anni sono emerse alcune forme di piastrinopenia ereditaria associate allo sviluppo di neoplasie di tipo ematologico e non ematologico che hanno destato un estremo interesse nei ricercatori; in particolare le forme associate a mutazioni di ANKRD26, RUNX1 e ETV6. Scopo Lo scopo di questo lavoro è quello di: 1. Costruire un database completo dei pazienti con piastrinopenia familiare finora pervenuti nel nostro laboratorio, definendo le mutazioni genetiche rinvenute. 2. Condurre uno studio preliminare sulla presenza di mutazioni in 5’UTR di ANKRD26 in pazienti con piastrinopenia sporadica e familiare, che non rientravano in forme note di piastrinopenia ereditaria e che presentavano volume piastrinico nella norma (4μm˂MPV˂8μm), definendone le caratteristiche cliniche e molecolari di questa nuova forma di piastrinopenia ereditaria e studiando le famiglie con mutazioni in questo gene. 3. Ampliare l’indagine ad altri due geni coinvolti in forme di piastrinopenia ereditaria con predisposizione a neoplasie ematologiche: RUNX1 ed ETV6. 4. Raccogliere e analizzare i dati relativi al corso della gravidanza in una ampia coorte di pazienti con forme di IT (inherited thrombocytopenia). Materiali e metodi Presso l’Unità di Clinica Medica 1 dell’Azienda Ospedale-Università di Padova è presente una casistica di circa 70 pedigree familiari di soggetti con piastrinopenia familiare da difetto ignoto. La valutazione comprende storia clinica e lo studio dell’espressione degli antigeni piastrinici di superficie mediante metodica citofluorimetrica utilizzando anticorpi monoclonali. Per valutare la morfologia piastrina è stato adottato il metodo della colorazione con May-Grunwald/Giemsa (MGG) su strisci di sangue periferico (macro, micro e normo trombocitopenia). Il DNA è stato estratto da sangue intero e amplificato per lo studio dei seguenti geni: GpIbα, GpIbβ, GpIX, MYH9, ACTN1. I prodotti delle reazioni di amplificazione sono stati visualizzati con elettroforesi su gel di agarosio marcato e quindi sequenziati con metodo di Sanger. Abbiamo condotto uno studio preliminare sulla presenza di mutazioni in 5’UTR di ANKRD26 in pazienti con piastrinopenia sporadica e familiare, che non rientravano in forme note di piastrinopenia ereditaria e che presentavano volume piastrinico nella norma (4μm˂MPV˂8μm) per poterne definire le caratteristiche cliniche e molecolari. Abbiamo quindi ampliato l’indagine a RUNX1 ed ETV6, due geni coinvolti in forme di piastrinopenia ereditaria con predisposizione a neoplasie ematologiche in pazienti piastrinopenici e non (MDS piastrinopenia +; MDS piastrinopenia -) appartenenti alle diverse classi di sindrome mielodisplastica sec. WHO 2008. Infine, nell’ambito delle piastrinopenie familiari confermate mediante indagine genetica, abbiamo partecipato al Pregnancy In Inherited Platelet Abnormalities (PIPA), studio multicentrico retrospettivo di valutazione di 339 gravidanze in 181 donne con 13 diverse forme di trombocitopenia. Risultati 8 famiglie (12%) presentano mutazioni nella MYH9, MYH9-related disease, 12 famiglie (19%) presentano mutazioni del gene GP1Bα, 4 famiglie (6%) presentano mutazioni del gene GP1Bβ che causano Bernard-Soulier Syndrome (BSS) mono o biallelico. Le rimanenti famiglie (60%) non presentano mutazioni genetiche sulle glicoproteine studiate, e nessuna mutazione sul gene ACTN1. Alla luce dei recenti studi relativi alle forme di piastrinopenie ereditarie caratterizzate, nel nostro laboratorio abbiamo condotto uno studio preliminare sulla presenza di mutazioni in 5’UTR di ANKRD26 in pazienti con piastrinopenia sporadica e familiare, che non rientravano in forme note di piastrinopenia ereditaria e che presentavano volume piastrinico nella norma (4μm˂MPV˂8μm), identificando due diverse mutazioni in eterozigosi, localizzate nella regione del 5’UTR non tradotta del gene. Dato l’interesse nello studio delle piastrinopenie ereditarie associate allo sviluppo di neoplasie di tipo ematologico e non ematologico, in particolare dei geni RUNX1 ed ETV6, responsabili di trombocitopenia non sindromica a trasmissione autosomica dominante, abbiamo preliminarmente raccolto una piccola casistica di soggetti mielodisplastici piastrinopenici (9 soggetti), di soggetti mielodisplastici con conta piastrinica nei limiti di norma (12 soggetti) e di 27 soggetti di controllo con trombocitopenia ereditaria indeterminata; questo per rinforzare le evidenze circa una possibile associazione tra mutazioni dei geni citati, piastrinopenia e rischio di evoluzione mielodisplastica/leucemica. Di questi soggetti abbiamo raccolto i dati relativi all’età, sesso, cariotipo, numero di blasti, emoglobina e piastrine. I dati preliminari (Tabella 1) dimostrano che le mutazioni dei geni RUNX1 e ETV6 sono presenti solo nel gruppo dei mielodisplastici piastrinopenici. GENE POSIZIONE MUTAZIONE RUNX-1 ESONE 4 c.76C>G RUNX-1 ESONE 8 c.934del A RUNX-1 ESONE 9 c.1214_1215insTG ETV6 INTRONE 1 c.28+192delC Tabella 1. Mutazioni rinvenute nei geni RUNX1 ed ETV6 Anche se il coinvolgimento di questi geni nella piastrinopoiesi è noto, l’esatto meccanismo responsabile di trombocitopenia non è ancora chiaro. La rarità di queste patologie rende difficile raccogliere dati utili ad una analisi genotipo-fenotipo. Nello studio multicentrico (PIPA) abbiamo classificato 23 gravidanze (13 donne): 5 donne presentano bBSS, 3 mBSS, 4 MYH9-RD, 1 ANKRD26. L’età media alla diagnosi di trombocitopenia è di 30 anni, la conta media piastrinica prima del parto è di circa 60 x 109 piastrine/L, anche se in alcuni casi è stata osservata una drastica riduzione piastrinica. La tendenza al sanguinamento è bassa prima del parto e solo in due gravidanze è stata necessaria la trasfusione di piastrine. Tutte le nascite sono avvenute tra la 34a e 40 a settimana; 13 sono i nati con parto cesareo e 10 con parto naturale. Solo 9 neonati riportano la stessa patologia della mamma, anche se in 6 casi il dato non è disponibile poiché non sono state fatte indagini a riguardo. Abbiamo riscontrato un unico caso di decesso neonatale a causa di emorragia cerebrale, ma nessun caso di sanguinamento nei nuovi nati. Conclusioni Le piastrinopenie rappresentano il più frequente disordine dell’emostasi e costituiscono un gruppo eterogeneo di entità cliniche. La peculiarità delle forme familiari risiede nella difficoltà della loro identificazione clinica poiché spesso le piastrinopenie vengono classificate come immuni ed i pazienti sottoposti a terapie inappropriate. Come riportato nei risultati di studi recenti che coinvolgono un numero di famiglie più elevato, anche nel nostro lavoro le forme più comuni di piastrinopenia familiare risultano essere la BSS, la MYH9-RD seguite dalla ANKRD26. Grazie ad una attenta analisi clinica ed alle indagini genetiche associate a recenti studi molecolari, ad oggi è possibile individuare e classificare correttamente i pazienti con nuove mutazioni genetiche considerando che ancora più del 50% delle famiglie non ha diagnosi. Per valutare possibili meccanismi implicati nello sviluppo di piastrinopenia in corso di sindromi mielodisplastiche sarà indispensabile studiare in modo estensivo queste tre categorie di pazienti: piastrinopenie ereditarie con difetto noto di ANKRD26, RUNX-1 e ETV6, mielodisplasie o leucemie con prevalente piastrinopenia. Aumentare la casistica di tali soggetti ci permetterà di approfondire lo studio funzionale delle mutazioni definendone le caratteristiche cliniche e molecolari, al fine di valutare un possibile link tra mielodiplasia e piastrinopenia e comprendere a che livello della megacariopoiesi e dell’ematopoiesi esse agiscano

In the last years there has been accumulating evidence that physical inactivity may accelerate the aging processes. Moreover, a genetic substrate that modulates the aging rate has been suspected in recent literature. However, it is possible that some genetic substrates actually act in an indirect way, modulating the levels of spontaneous physical activity. Therefore the present work investigates (i) the genetic determinants of spontaneous physical activity and (ii) using an experimental approach, the effects of physical activity on cognitive impairment have been addressed. Given the great complexity of the study of genetic determinants in humans, we have taken advantage of the technology introduction of transgenic animals. Specifically, through a meta-analysis approach, the brain distribution of genes that are involved in the change of locomotor activity has been investigated. To this aim, about 50000 abstracts and papers in extenso concerning behavioral studies in knockout mice have been analyzed; data have been collected in a database and crossed to two databases, the Allen Brain Atlas and the Sym Atlas, to verify the brain distribution of genes deleted. Results show that the genes accompanied, after deletion, by an increase of locomotor activity are expressed at higher levels in all brain regions compared to those that after deletion cause locomotor hypoactivity. Therefore, we investigated how the levels of spontaneous physical activity are distributed in an aged population. To this aim, 438 subjects (age 50-86 years) have been characterized for their motor ability (AAPHERD battery), their spontaneous physical activity (test PASE) and their cognitive status (tests MMSE, FAB, attentional matrix). Moreover subjects have been randomized in two experimental groups, the first one fulfilling an intense aerobic and potentiation physical training protocol, and a second one with a light aerobic training. The training, three times per week, one hour per session, lasted for one year. After six months and one year subjects have been tested again using the above battery of tests. Results at six months show that spontaneous physical activity has a bimodal distribution in male aged population. Noteworthy, strong differences have been noted between the groups of more active aged subjects compared to the less active ones: the first takes less drugs and has better scores in agility tests and in attentional tests. To verify the causal relationship between physical activity and these variables, we compared the scores before and after the physical training. Results confirm that physical activity decrease the number of drugs and improves motor abilities. However, attentional scores do not improve after this specific physical training. In conclusion, murine models suggest a genetic substrate for differences in physical activity in the population; data from the aged population suggest that levels of spontaneous physical activity, caused by, at least in part, genetic substrates, could cause the decrease of physical abilities and the increase in the number of drugs taken during ageing process.
Negli ultimi anni si è accumulata l’evidenza che l’inattività fisicapuò accelerare i processi d’invecchiamento. Inoltre, si sospetta un substrato genetico che moduli la velocità d’invecchiamento. È possibile, però, che almeno alcuni di tali substrati genetici invero operino in modo indiretto, modulando i livelli spontanei di attività fisica di un individuo. Pertanto nel presente lavoro sono stati studiati (i) i determinanti genetici dell’attività fisica spontanea e(ii) con uno studio di tipo sperimentale, sono stati affrontati gli effetti dell’attività fisica sul deterioramento cognitivo.Data la complessità dello studio dei determinanti genetici del comportamento, abbiamo sfruttato l’introduzione della tecnologia degli animali transgenici. In particolare, attraverso un lavoro di metanalisi, abbiamo indagato la distribuzione cerebrale di geni che sono coinvolti nel cambiamento dell’attività locomotoria. A tale scopo sono stati analizzati circa 50000 abstract e lavori in extenso relativi a studi comportamentali in animali knockout; i dati sono stati tabulati ed incrociati con altri database quali l’Allen Brain Atlas e il Sym Atlas per conoscere la distribuzione cerebrale dei geni deleti. I risultati dimostrano che i geni accompagnati, dopo delezione, da un aumento dell’attività locomotoria sono più espressi in tutte le regioni cerebrali paragonati a quelli che dopo delezione danno ipoattività locomotoria. Abbiamo voluto, pertanto, indagare come i livelli di attività fisica spontanea si distribuiscono in una popolazione anziana. A tale scopo 438 soggetti (età 50-86 anni) sono stati caratterizzati per le loro abilità motorie (tests AAPHERD), la loro attività fisica spontanea (tests PASE), e il loro status cognitivo (tests MMSE, FAB, matrici attenzionali). Inoltre i soggetti sono poi stati randomizzati in due gruppi sperimentali, il primo con un protocollo di allenamento aerobico e di potenziamento intenso ed il secondo con un allenamento lieve, aerobico. L’allenamento, tre volte a settimana, un’ora a seduta è durato un anno. A distanza di sei mesi e un anno i soggetti sono stati nuovamente testati con la batteria di test sopra descritti. I risultati a sei mesi indicano chel’attività fisica spontanea ha una distribuzione bimodale nella popolazione anzianamaschile. È importante sottolineare che si osservano notevoli differenze fra il gruppo di anziani più attivo e quello meno attivo: il primo assume meno farmaci, ed haun miglior punteggio in test di abilità motoria e di attenzione. Per verificare la relazione causale fra attività fisica spontanea e tali variabili, abbiamo comparato i punteggi prima e dopo allenamento. I risultati confermano che il numero di farmaci si riduce e le abilità motorie migliorano con l’allenamento proposto, mentre le abilità attenzionali non sembrano modificarsi. In conclusione, i modelli murini suggeriscono un substrato genetico per i diversi livelli basali di attività fisica nella popolazione; i dati sulla popolazione anziana suggeriscono che i livelli di attività fisica spontanea, almeno in parte di origine genetica, potrebbe causare le ridotte abilità fisiche e l’aumentato numero di farmaci assunti con l’invecchiamento.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Universidade Estadual Paulista (UNESP)
Visando contribuir para o melhor entendimento do papel dos polimorfismos em genes de citocinas na susceptibilidade para hanseníase, foi conduzido um estudo de associação do tipo caso-controle investigando polimorfismos de base única (SNPs) nas regiões promotoras dos genes IL10 (-819C>T, -1082A>G, -2763A>C, -2849A>G e -3575T>A) e TNF (TNF-308G>A) e no gene LTA (LTA+80C>A e LTA252A>G). Amostras de DNA genômico foram obtidas de 545 pacientes com hanseníase e 380 controles, provenientes do Estado de São Paulo. As genotipagens foram feitas pelas técnicas de PCR e polimorfismo de comprimento dos fragmentos de restrição (RFLP). Para as análises estatísticas foram calculadas as freqüências alélicas, de genótipos e de portadores para cada polimorfismo avaliado. As freqüências de haplótipos foram estimadas por meio do método de máxima verossimilhança. Desvios da lei do equilíbrio de Hardy-Weinberg foram testados empregando testes de Qui-quadrado. Modelos de regressão logística com cálculo de odds ratio (OR) e p-valor com ajustes para as co-variáveis gênero e etnia foram utilizados nas comparações das freqüências entre casos e controles. Em análise isolada, os polimorfismos TNF-308G>A e LTA252A>G não apresentaram associação significativa com a doença, já para o polimorfismo LTA+80C>A, os genótipos AA e CA mostraram-se marginalmente associados com OR de proteção (0,68 e 0,80, respectivamente e mesmo p-valor corrigido=0,07) para hanseníase per se. Confirmando ainda o sentido desta associação, a análise de carreador para o polimorfismo no locus LTA+80 mostrou associação com proteção para hanseníase per se para os carreadores do alelo A (OR=0,78; p-valor corrigido=0,04). Na análise de haplótipos, LTA+80A/LTA+252A/TNF-308G foi também associado com proteção (OR=0,74; p-valor corrigido=0,02). Para a região promotora do gene IL10, o SNP - 819C>T foi...
To the better understanding of the role of genetic polymorphisms at cytokines genes on leprosy susceptibility, we conducted a case-control association study investigating single nucleotide polymorphisms (SNPs) located at promoter region of IL10 (-819C>T, -1082A>G, -2763A>C, -2849A>G and -3575T>A) and TNF genes (TNF-308G>A) and LTA gene (LTA+80C>A e LTA252A>G) gene. Genomic DNA samples were obtained from 545 leprosy patients and 380 controls, from State of São Paulo. Genotyping were done by PCR followed by restriction fragments length polymorphisms (RFLP) analyses. For statistical analyses were calculated allelic, genotypes and carriers frequencies for each polymorphism. The haplotypes frequencies were estimated using maximum-likelihood estimation method. Chisquare tests for deviation from Hardy-Weinberg equilibrium were also performed. Logistic regression models for odds ratio (OR) and p-value calculations, with adjusting for the ethnicity and gender covariates, were performed in comparisons of frequencies. Isolated, TNF-308G>A and LTA252A>G were not significantly associated to the disease, while the CC and CA genotypes to LTA+80C>A locus were marginally associated with protection (0.68 e 0.80, respectively and identical corrected p-value=0.07) for leprosy per se. In the same line, carrier analysis for LTA+80 locus showed association with protection for leprosy per se for allele A carriers (OR=0.78; corrected p-value=0.04). In the haplotype analysis, LTA+80A/LTA+252A/TNF-308G was also associated to protection (OR=0.74; corrected p-value=0.02). From IL10 promoter region analysis, -819C>T SNP was associated with susceptibility to leprosy per se to TT (OR=1.58; p-value=0.05) and CT genotypes (OR=1.36; p=0.05). This association could be confirmed in the carriers analysis for -819T allele (OR=1.40; p-value=0.02 and OR=1.39; corrected pvalue= 0.03). From haplotypic analysis for IL10 ... (Complete abstract click electronic access below)

Thesis (MSc (Genetics))—University of Stellenbosch, 2007.
In South Africa, pre-eclampsia is the second highest cause of maternal deaths. The incidence of this disease in the Western Cape alone is 6.8% and places a large burden of health care facilities. The placenta and implantation thereof is thought to play the most significant role in the onset of this disease. Among the many theories for its aetiology, is the acknowledged two - stage theory. This is based on evidence that pre-eclamptic placentas demonstrate altered remodelling and invasion into the uterine endometrium and myometrium. The sub-optimal endometrium invasion leads to less oxygenation of the placental environment causing transient hypoxia. Consequently, the placenta is thought to release unknown factors into the maternal circulation which then culminates in clinical features associated with pre-eclampsia. Neurokinin B is thought to be one of these placental factors and subsequently binds to the NKB receptor in the maternal system. Endothelium-derived nitric oxide synthase has recently been shown to activate this receptor. The aim of this study was to investigate the role of neurokinin B (TAC3) and the neurokinin B receptor (TACR3) genes in the predisposition of pre-eclampsia and their interaction with eNOS in the South African coloured population together with a matched control cohort.

The overall aims of this thesis were to investigate psychological and behavioral effects of receiving cancer genetic counseling for breast, ovarian and colorectal cancer and/or with a family history of these cancer types and to determine whether counselees’ informational needs were met. Study I was performed 3-7 years post-counseling. Participants (n=214) reported a relatively high level of anxiety but a low level of depression compared to cancer patients in general. However, there was no indication that the distress experienced was due to the counseling. Moderate changes in life and family relations, high level of adherence to recommended controls and satisfaction was reported. Study II was a randomized control trial (RCT) intervention study which involved 147 counselees. An increase in the level of knowledge and correct estimation of personal risk was reported in both the intervention and control groups, although this increase declined at later follow-up. Enhanced information led to significantly greater satisfaction with the given information, and the way of informing relatives. Most counselees had shared information with their at-risk relatives. Study III focused on sharing information with at-risk relatives among participants in study II and their relatives (n=81). Counselees were interviewed and answered a questionnaire, whilst their relatives only answered the questionnaire. Counselees reported positive/neutral feelings about communicating genetic information and mostly interpreted their relatives’ reactions as positive/ neutral. Also, approximately 50% of relatives reported positive/neutral reactions and were generally satisfied with the received information. Study IV was conducted in Sweden and Norway based on 235 counselees. Counselees expected counselors to be skillful and thoughtful, take them seriously and provide risk estimations and medical information. Most important issues to counselees were satisfactorily addressed by the counselors. Analyzing importance rankings resulted in five categories of needs: a need for facts, caring communication and medical information, need for understanding and support in sharing genetic information, practical care and medical/practical information. In conclusion, no adverse psychological or behavioral effect on counselees was observed. Apparently, genetic counseling is managed properly and counselors successfully address counselees’ needs. Providing extended information does not seem necessary, however, tailoring information to individual counselees needs may create a more effective counseling.

Thesis (MSc)--University of Stellenbosch, 2007.
ENGLISH ABSTRACT: The World Health Organisation (WHO) has defined preterm labour as the onset of labour before 37 completed weeks of gestation with an incidence ranging between 5-10%. Although patient care has improved, the rate of preterm birth has slowly been increasing and currently impacts significantly on maternal and fetal mortality and morbidity. The complex condition of preterm labour involves multiple etiologies and risk factors, which complicates the search for candidate markers and / or biomarkers. The aim of this prospective study was to investigate potential genetic associations with preterm labour. The study cohort consisted of consecutive first-time booking, low-risk primigravid pregnant women from a restricted geographical region. The study cohort comprised 421 [306 Coloured and 115 Black] pregnant women presenting at the Paarl Hospital Obstetric clinic. Subsequently, DNA was extracted from whole blood and investigated for a range of known polymorphisms in pro-inflammatory and anti-inflammatory cytokines, as well as the novel LGALS13 gene, for potential variants that may impact on pregnancy outcome. Screening techniques involve combinations of allele-specific PCR amplification, Multiphor SSCP/HD analysis, restriction enzyme analyses and DNA sequencing. A significant association was demonstrated between the IL-1RN*2-allele and adverse pregnancy outcome, mainly in the preterm labour and hypertension group. The presence TNFα-308 A-allele was associated with overall adverse pregnancy outcome and preterm labour. In addition to this, a novel IL-1RN allele was identified in the control group. Mutation screening and subsequent statistical methods revealed an association between a novel LGALS13 exonic variant, 221delT, and preterm labour in Coloured women. Two previouslydocumented intronic variants (IVS2-22A/G and IVS3+72T/A) demonstrated linkage disequilibrium, signifying evolutionary conservation of exon three. Additionally, two novel intronic variants, IVS2-36 G/A and IVS2-15 G/A, demonstrated no association with adverse pregnancy outcome. In this study we identified rare novel exonic variants; two non-synonymous variants in exon three (M44V, [N=2] and K87R, [N=1]) and a silent variant in exon four (P117P, [N=1]) - all identified in individuals from the control cohort. Within coding exon three, an interesting variant [“hotspot”] was identified, which represents six polymorphic bases within an 11bp stretch. No associations were demonstrated with these variants and pregnancy outcome. Furthermore, a previously documented 5' “‘promoter” variant, -98 A/C, was identified and demonstrated no association with adverse pregnancy outcome. However, subdivision of lateonset pre-eclamptic cases revealed a significant association with the A-allele and late-onset preeclampsia. Genotype-phenotype investigation demonstrated association between the IL-10 -1082 A/G, IL-4 C/T and 221delT loci and poor pregnancy progress which manifested as (i) delivery of infants weighing <2000g, (ii) before 37 weeks of gestation. The findings of this study will strengthen our understanding of the pathophysiology underlying pregnancy complications and facilitate the further development of effective treatment strategies to reduce maternal and fetal morbidity and mortality.
AFRIKAANSE OPSOMMING: Die Wêreld Gesondheid Organisasie (WHO) klassifiseer voortydse kraam as kontraksie voor 37 volledige weke, met ‘n insidensie tussen 5-10%. Alhoewel pasiënte-sorg verbeter het, neem die tempo van voortydse geboorte steeds toe, wat ‘n groot impak het op moederstrefte en fetale mortaliteit en morbiditeit. Die komplekse kondisie van voortydse kraam sluit veelvoudige oorsake en risiko faktore in, wat die navorsing van kandidaat en / of biologiese merkers kompliseer. Die doel van hierdie prospektiewe studie, was die potensiële navorsing van genetiese assosiasies met voortydse kraam. Die studie kohort bevat opeenvolgende eerste bespreking van lae risiko primigravida swanger vrouens vanaf ‘n beperkte geografiese omgewing. Die studie kohort beslaan 421 [306 Kleurling en 115 Swart] swanger vrouens teenwoordig by die Paarl Hospitaal Verloskunde kliniek. Vervolgens was DNS geëkstraeer van bloedmonsters en geondersoek vir ‘n verskeidenheid van bekende polimorfismes in pro-inflammatoriese en antiinflammatoriese sitokiene, insluitend die nuwe sifting van die LGALS13 geen potensiaal vir variante wat ‘n impak op swangerskap uitkomste sal hê. Die siftings tegnieke toegepas, sluit in ‘n kombinasie van alleel-spesifieke amplifikasie, Multiphor enkelstring konformasie polimorfisme / heterodupleks analise, restriksie ensiem verterings en volgorde bepalings tegnieke. ‘n Betekenisvolle assosiasie was gedemonstreer tussen die IL-1RN*2-alleel en nadelige swangerskap, beperk tot voortydse kraam en die hipertensie groep. Die teenwoordigheid van die TNFα-308 A-alleel was geassosieer met algehele nadelige uitkomste en voortydse kraam. Daarby, was ‘n nuwe IL-1RN alleel geïdentifiseer in die kontrole groep. Mutasie sifting en opeenvolgende statistiese metodes, het ‘n assosiasie getoon tussen ‘n nuwe LGALS13 koderende variant, 221delT, en voortydse kraam in Kleurling vrouens. Twee voorafbeskryfde introniese variante (IVS2-22 A/G en IVS3+72 T/A), het ‘n betekenisvolle bewys opgelewer dat daar koppelings-onewewig bestaan tussen hierdie variante, en toon evolusionêre konservasie van ekson drie. Addisioneel was twee nuwe introniese variante ontdek, IVS2-36 G/A en IVS2-15 G/A, wat geen assosiasie getoon nie. In hierdie studie het ons ‘n nuwe seldsame koderende variante geïdentifiseer in die kontrole groep, waarvan twee nie-sinonieme variante was in ekson drie (M44V, N=2 en K87R, N=1) en ‘n stil variasie in ekson vier (P117P, N=1). Geleë in die koderende area van ekson drie, was ’n interessante variant [“hotspot’] ontdek, waarvan ses basisse in ‘n 11 basis paar area polimorfies is. Geen assosiasie was getoon met hierdie variante en swangerskap uitkomste nie. Verder was ‘n voorafbeskryfde 5' ‘promotor’ variant, -98 A/C, geïdentifiseer wat geen assosiasie getoon met nadelige swangerskap uitkomste nie. Onderverdeling van laat-aanvangs preeklampsie, het getoon dat die A-alleel ‘n betekenisvolle assosiasie getoon het met die ontwikkeling van laat pre-eklampsie. Genotipe-fenotipe interaksies het ’n assosiasie getoon tussen die IL-10 -1082 A/G, IL-4 C/T en 221delT lokusse en nadelige swangerskap uitkomste, wat manifesteer as (i) kraam van suigelinge wat <2000g weeg, (ii) geboorte voor 37 weke. Die bevindings van hierdie studie sal ons basiese kennis verbeter oor die patologie beskrywend aan swangerskap komplikasies, asook die fasilitering en ontwikkeling van effektiewe behandelings strategieë, om moederstrefte en fetale mortaliteit en morbiditeit te verminder.

[Truncated abstract] This thesis investigates novel methods for the genetic association analysis of haplotype data in samples of unrelated individuals, and applies these methods to the analysis of coronary heart disease and related phenotypes. Determining the inheritance pattern of genetic variants in studies of unrelated individuals can be problematic because family members of the studied individuals are often not available. For the analysis of individual genetic loci, no problem arises because the unit of interest is the observed genotype. When the unit of interest is the linear combination of alleles along one chromosome, inherited together in a haplotype, it is not always possible to determine with certainty the inheritance pattern, and therefore statistical methods to infer these patterns must be adopted. Due to genotypic heterozygosity, mutliple possible haplotype configurations can often resolve an individual's genotype measures at multiple loci. When haplotypes are not known, but are inferred statistically, an element of uncertainty is thus inherent which, if not dealt with appropriately, can result in unreliable estimates of effect sizes in an association setting. The core aim of the research described in this thesis was to develop and implement a general method for haplotype-based association analysis using multiple imputation to appropriately deal with uncertainty haplotype assignment. Regression-based approaches to association analysis provide flexible methods to investigate the influence of a covariate on a response variable, adjusting for the effects of other variables including interaction terms. ... These methods are then applied to models accommodating binary, quantitative, longitudinal and survival data. The performance of the multiple imputation method implemented was assessed using simulated data under a range of haplotypic effect sizes and genetic inheritance patterns. The multiple imputation approach performed better, on average, than ignoring haplotypic uncertainty, and provided estimates that in most cases were similar to those observed when haplotypes were known. The haplotype association methods developed in this thesis were used to investigate the genetic epidemiology of cardiovascular disease, utilising data for the cholesteryl ester transfer protein gene (CETP), the hepatic lipase (LIPC) gene and the 15- lipoxygenase (ALOX15) gene on a total of 6,487 individuals from three Western Australian studies. Results of these analyses suggested single nucleotide polymorphisms (SNPs) and haplotypes in the CETP gene were associated with increased plasma high-density lipoprotein cholesterol (HDL-C). SNPs in the LIPC gene were also associated with increased HDL-C and haplotypes in the ALOX15 gene were associated with risk of carotid plaque among individuals with premature CHD. The research presented in this thesis is both novel and important as it provides methods for the analysis of haplotypic associations with a range of response types, while incorporating information about haplotype uncertainty inherent in populationbased studies. These methods are shown to perform well for a range of simulated and real data situations, and have been written into a statistical analysis package that has been freely released to the research community.

Obesity is a complex disorder which has reached epidemic proportions in many parts of the world. Twin studies have demonstrated a high heritability for obesity. The subsequent appli-cation of genome wide association studies (GWAS) in the last decade have identified at least 32 genetic loci associated with body mass and obesity. Despite these great advances, these loci are almost exclusively completely naïve in a functional context. Genetic variations within the gene encoding the fat mass and obesity associated gene (FTO) are the strongest and most consistently observed genetic variants associated with obesity and body mass throughout various studied populations from all parts of the world. The identification of association of FTO with obesity has spurred immense interest in the function of the FTO protein and the functional consequences of its variants. However, the implications of genetic variants at other genetic loci on protein molecular function and body mass development remain undetermined. This thesis aims to examine more closely four of the genetic loci associated with obesity; in proximity of, or associated with: FTO, TMEM18, MAP2K5 and STK33, in two cohorts of children of European descent: a case-control of clinically obese children and normal weight controls from the Stockholm area; and a cross sectional cohort of Greek children. These smaller cohorts allow for studies of more specific effects of genetic variants as individuals in these cohorts can be more carefully studied. TMEM18 gene expression was also studied in the rat-brain where a positive correlation was observed between the body weight of the animal and TMEM18 expression. We also employed next generation sequencing to more carefully study obesity-associated genetic loci related to FTO and TMEM18. We utilized a novel strategy in this project to study genetic variation in the entire FTO- and TMEM18 genes, as well as in the GWAS-identified BMI-associated loci located downstream from TMEM18. This analysis was performed on a case-control cohort of Swedish children (n = ~1000). Through this analysis, we were able to observe genetic variants within intron 1 of the FTO gene to be the main genetic variants asso-ciated with obesity at this locus. We also observed, for the first time, obesity-associated genetic variants within the gene encoding TMEM18. To analyze the potential functional context of FTO we used an in silico approach, utilizing public information databases on mRNA co-expression and protein-protein interaction. Based on our findings, we speculate on a wider functional role of FTO in extracellular ligand-induced neuronal plasticity, possibly via interaction or modulation of the BDNF/NTRK2 signaling pathway.

This thesis contributes to the Human Genome Project by adding detail to the physical and genetic maps of the human genome, and by identifying a strong candidate gene for a form of distal myopathy. Genomic clones for the human skeletal muscle genes slow troponin (TNN/1), alpha actin (ACTA1), and (3-tropomyosin (TPM2) were isolated for use in the fluorescent in situ hybridisation localisation of these genes on the cytogenetic map of the human genome. The localisation of these genes made them potential candidates for inherited skeletal muscle diseases, including the muscular dystrophies investigated here. Microsatellite, VNTR and RFLP markers were used in a search for linkage to a novel form of distal myopathy segregating in a Western Australian family. The decadic logarithm of the likelihood ratio, or 'lod score' method, was used to determine linkage between markers and this distal myopathy gene. A 22.4 cM candidate region was identified at 14q11.2. This was the first localisation of a distal myopathy gene. The Human Genome Organisation Nomenclature Committee reserved MPD1, 'myopathy, distal 1 ', for this form of distal myopathy, now known as Laing myopathy. The MPD1 candidate region was excluded as the disease gene location for two other forms of distal myopathy. Silburn myopathy in 1994, which established the genetic heterogeneity of distal myopathy, and Felice myopathy in 1996. The exclusion of the MPD1 and French-Canadian OPMD candidate regions as disease gene locations for a putative-OPMD segregating in a Western Australian family, proved that this disease gene did not lie at 14q11.2. Testing an MPD1 muscle-specific candidate gene for the Laing myopathy mutation, the myosin heavy polypeptide 7 gene (MYH7), identified seven base changes between the MPD1 proband sequence and the published MYH7 eDNA sequence. All of these base changes were found in eight unrelated, unaffected Western Australians, therefore none of them were the Laing myopathy mutation. Two further differences to the published MYH7 sequence segregated exclusively with the MPD1 proband. One of these, the MYH7 G5073C (cDNA)/G23628C (gDNA) base change, caused a critical change to the MYH7 13-myosin heavy chain polypeptide product (13-MyHC). An A 1663P 13-MyHC substitution. G23628/C 23628 segregated with Laing myopathy in the Western Australian distal myopathy family. This segregation was confirmed by a single-strand conformation polymorphism test, then used to test 256 unaffected chromosomes. None possessed MYH7C23628. Two patients from European distal myopathy families phenotypically similar to Laing myopathy, the Voit and Scoppetta families, were tested for the presence of MYH7 gDNA G23628/C23628 heterozygosity. Both were homozygous MYH7 G23628. One of these patients (Voit) was also tested for MYH7 eDNA G5073/C5073 heterozygosity. She was homozygous MYH7 G5073. An analysis of the effect of the 13-MyHC A 1663P substitution at various levels of protein structure strengthened the candidature of MYH7 G5073C as the Laing myopathy mutation. It demonstrated the extreme rarity of the 13-MyHC A 1663P substitution; it showed that this substitution did have a detrimental effect on coiled-coil formation; and it identified ways in which the 13-MyHC A 1663P substitution could disrupt myofibrillogenesis or contractility. Future research directions are identified and the contribution of this work to evolving concepts in muscular dystrophy is evaluated.

Thesis (MSc (Genetics))--University of Stellenbosch, 2009.
Pre-eclampsia is one of the most common hypertensive disorders of pregnancy in South Africa. Presently, the only cure for pre-eclampsia is delivery, which brings with it, additional complications. As an alternative, clinical management of this disorder relies on timely diagnosis. The predictive biomarker, Placental Protein 13 (PP13), is currently used for the early diagnosis of pre-eclampsia, in an ELISA-based diagnostic kit, developed by Diagnostic Technologies Limited (DTL)1. A decrease in serum PP13 levels has been reported during the first trimester of pregnancy in women who later develop pre-eclampsia. The function of PP13 has not been fully elucidated and it is also not known whether the reduction in PP13 levels is a cause or an effect of the disease. The use of PP13 as a predictive biomarker for pre-eclampsia therefore warrants a comprehensive study of this peptide and the encoding gene, LGALS13. The aim of this study was firstly to characterise LGALS13 using a range of in silico tools. PP13 was found to be most homologous to the predicted protein product of a neighbouring “putative” gene, LOC148003. A gene conversion event between these two genes most likely underlies the so-called “hotspot mutation” in LGALS13. Data also demonstrates that the DelT mutation disrupts functionally and structurally important features of the gene and peptide sequences. Through the analysis of the putative promoter region of LGALS13, the presence of a Stimulatory protein-1 (Sp1) binding sequence element was predicted, which has implications for regulation of LGALS13. Secondly, the study aimed to establish a study cohort for the investigation of the effect that the LGALS13 genotype has on the expression of its mRNA and protein products. Serum, plasma and whole blood samples were collected and prepared from 316 pregnant women. Placental tissue samples were obtained from a selected group of these subjects for RNA extraction. Once the sampling on the two remaining targeted deliveries has occurred, the collection of samples will be batched and sent to DTL in Israel, for PP13 measurement. DNA was extracted from the whole blood samples obtained, and all study participants were genotyped for seven sequence variants within the LGALS13 gene using (i) Multiphor Single Stranded Conformational Polymorphism and Heteroduplex (SSCP/HD) analysis, (ii) restriction enzyme analysis and (iii) DNA sequencing. The genotype data sets will be compared with PP13 levels when they become available, and also with clinical parameters, once the deliveries have all occurred and the database is complete. This study demonstrated the power of an in silico approach to direct the focus of future experimental work. The newly established study cohort will be used for prospective studies aiming at a better understanding of the role which LGALS13 and PP13 play in the early prediction of preeclampsia.

In malaria-endemic regions, Plasmodium falciparum (P. falciparum) infection is characterized by extensive genetic/antigenic diversity. Describing this diversity provides important information about the local molecular epidemiology of infecting P. falciparum parasites. Intriguingly, one of the major obstacles to the development of an effective malaria vaccine has been the genetic polymorphisms exhibited by P. falciparum genes encoding targets of human immune system. This situation has necessitated the development of polyvalent vaccines with wide antigenic coverage that would increase the likelihood of vaccine efficacy that covers wide geographical areas of malaria endemic countries. Limited reports are available on the population genetic diversity and structure of P. falciparum in Malawi, and this is of particular concern as the country has put in place several interventions to combat the disease. The primary aim of the research project was to determine the genetic diversity and population structure of P. falciparum isolates and comparing complexity from four different epidemiological settings in Malawi using msp-2 gene polymorphisms. Samples were collected from four epidemiological locations in the north, centre and southern regions of Malawi. The diversity and genetic differentiation of P. falciparum populations were analyzed based on the highly polymorphic block 3 msp-2 gene. One hundred and twenty patient samples who presented with signs and symptoms of malaria and who had microscopically confirmed P. falciparum infection were enrolled in the study after they had satisfied the inclusion criteria. Parasite DNA was extracted from the blood spot on to filter paper and analyzed by genotyping the msp-2 gene using allele-specific nested PCR. A total of 28 msp-2 block 3 fragments, defined by the size and the allelic types were detected in the 102 patients. The length variants of the PCR product ranged from 240basepairs (bp) to 450bp for the K1/FC and 410bp to 780bp for the 3D7/IC allelic families. Isolates of the 3D7 alleles were predominant in the population (59 percent), compared to isolates of the K1/ FC27 alleles (41 percent) and for 3D7 and K1 most of the isolates were monoclonal infections. In comparisons between the sites, we observed the highest prevalence of mixed infection in Mwanza (46.7 percent) followed by Dwangwa (23.3 percent) compared to Bolero (16.7 percent) and Mitundu (16.7 percent). The difference in prevalence of mixed infections between Mwanza and the other sites was statistically significant (p=0.041). There was also a non-significant trend towards a higher mean genotype number per isolate in the children aged >5 years compared to those below 5 years of age. These data suggest differences in prevalence rates of mixed infections in different geographical/epidemiological settings in Malawi. Further studies are needed to confirm, with larger sample sizes, the observation of a non-significant trend towards higher multiclonality of infection in older children in malaria endemic areas of Malawi.

Identification and understanding of the molecular events involved in colorectal cancer (CRC) pathogenesis should lead to better comprehension of the disease process, hopefully leading to better prognostic stratification, and as a result more targeted treatment regimens and improved patient outcomes. A sub group of sporadic CRC exhibit microsatellite instability (MSI). MSI is seen when the fidelity of DNA replication is impaired. Cancers may be categorized as MSI-high (MSI-H), MSI-low (MSI-L), or microsatellite stable (MSS), according to the degree of MSI exhibited. This research project was designed to analyse the association between MSI—H and MSI-L, clinicopathological features and survival in an unselected group of patients with sporadic Australian Clinicopathological Stage (ACPS) C / American Joint Committee on Cancer (AJCC) stage III CRC, i.e. patients with lymph node metastases at the time of surgical resection of their cancer. The criteria used to determine MSI, specifically the type and number of microsatellite markers used, were also reviewed. 255 patients who underwent resection for sporadic ACPS stage C CRC were studied; none of these patients received chemotherapy. Archival normal and tumour DNA were extracted and amplified by polymerase chain reaction using a radioactive-labelling technique and a panel of internationally recognised microsatellite markers. MSI-H was defined as instability in 2 40% of 7 markers, MSI-L as instability at > 0% but < 40% of 11 markers, and M88 as no instability. Twenty one MSI-H and 33 MSI-L CRC were identified. Significant results included that MSI-H tumours are more commonly right sided (p < 0.00001); larger (p 5 0.0005); more likely to be high grade (p = 0.049); and, after adjustment for age, sex and other pathology variables, associated with improved survival (p = 0.015). No difference was found between the biological characteristics of MSI-L and MSS CRC. MSI-L CRC showed a trend towards poorer cancer-specific survival than MSS CRC but this difference did not reach statistical significance. Although dependent on the number and type of microsatellites used, similar trends in the results were seen when different criteria were used to determine MSI. This study has contributed to the rapidly expanding literature on CRC carcinogenesis and, at the time completed, was one of the first to show an association between MSI-H and improved survival in clinicopathological stage C CRC patients who had not received chemotherapy. It supports the view that identification of MSI status in patients with sporadic ACPS C / AJCC stage III tumours may help stratify patients according to prognosis and should be considered in therapeutic decision making and future trials of adjuvant therapy. However to accurately determine the clinical usefulness of MSI more precise standardisation of the definition and methodologies used to identify M81 is required.

Šiame magistro baigiamajame darbe lyginamuoju metodu yra analizuojamas preimplantacinės diagnostikos reguliavimas įvairiose pasaulio valstybėse, tuo pačiu atskleidžiant pagrindines iš to kylančias problemas. Tyrimas atliktas siekiant palyginti skirtingų valstybių teisės aktus ir patirtį šioje biomedicinos srityje. Atlikta analizė rodo, kad preimplantacinė diagnostika vis dar yra pakankamai nauja ir atsargiai vertinama procedūra, sukelianti daug etinių ir teisinių diskusijų, o teisinis reguliavimas priklauso nuo valstybės teisinių, religinių, kultūrinių, socialinių tradicijų.
These master theses analyze the regulation of preimplantation genetic diagnosis in comparative aspect in different countries, simultaneously revealing main problems arising. The aim of this research is to compare legal acts and experience of different countries in this biomedical field. The analysis shows, that preimplantation genetic diagnosis is still innovative and well considered procedure, which give a rise to a lot of ethical and legal discussions, and legal regulation of this procedure depends on legal, religious, cultural and social traditions of the country.

Resumo: Visando contribuir para o melhor entendimento do papel dos polimorfismos em genes de citocinas na susceptibilidade para hanseníase, foi conduzido um estudo de associação do tipo caso-controle investigando polimorfismos de base única (SNPs) nas regiões promotoras dos genes IL10 (-819C>T, -1082A>G, -2763A>C, -2849A>G e -3575T>A) e TNF (TNF-308G>A) e no gene LTA (LTA+80C>A e LTA252A>G). Amostras de DNA genômico foram obtidas de 545 pacientes com hanseníase e 380 controles, provenientes do Estado de São Paulo. As genotipagens foram feitas pelas técnicas de PCR e polimorfismo de comprimento dos fragmentos de restrição (RFLP). Para as análises estatísticas foram calculadas as freqüências alélicas, de genótipos e de portadores para cada polimorfismo avaliado. As freqüências de haplótipos foram estimadas por meio do método de máxima verossimilhança. Desvios da lei do equilíbrio de Hardy-Weinberg foram testados empregando testes de Qui-quadrado. Modelos de regressão logística com cálculo de odds ratio (OR) e p-valor com ajustes para as co-variáveis gênero e etnia foram utilizados nas comparações das freqüências entre casos e controles. Em análise isolada, os polimorfismos TNF-308G>A e LTA252A>G não apresentaram associação significativa com a doença, já para o polimorfismo LTA+80C>A, os genótipos AA e CA mostraram-se marginalmente associados com OR de proteção (0,68 e 0,80, respectivamente e mesmo p-valor corrigido=0,07) para hanseníase per se. Confirmando ainda o sentido desta associação, a análise de carreador para o polimorfismo no locus LTA+80 mostrou associação com proteção para hanseníase per se para os carreadores do alelo A (OR=0,78; p-valor corrigido=0,04). Na análise de haplótipos, LTA+80A/LTA+252A/TNF-308G foi também associado com proteção (OR=0,74; p-valor corrigido=0,02). Para a região promotora do gene IL10, o SNP - 819C>T foi ... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: To the better understanding of the role of genetic polymorphisms at cytokines genes on leprosy susceptibility, we conducted a case-control association study investigating single nucleotide polymorphisms (SNPs) located at promoter region of IL10 (-819C>T, -1082A>G, -2763A>C, -2849A>G and -3575T>A) and TNF genes (TNF-308G>A) and LTA gene (LTA+80C>A e LTA252A>G) gene. Genomic DNA samples were obtained from 545 leprosy patients and 380 controls, from State of São Paulo. Genotyping were done by PCR followed by restriction fragments length polymorphisms (RFLP) analyses. For statistical analyses were calculated allelic, genotypes and carriers frequencies for each polymorphism. The haplotypes frequencies were estimated using maximum-likelihood estimation method. Chisquare tests for deviation from Hardy-Weinberg equilibrium were also performed. Logistic regression models for odds ratio (OR) and p-value calculations, with adjusting for the ethnicity and gender covariates, were performed in comparisons of frequencies. Isolated, TNF-308G>A and LTA252A>G were not significantly associated to the disease, while the CC and CA genotypes to LTA+80C>A locus were marginally associated with protection (0.68 e 0.80, respectively and identical corrected p-value=0.07) for leprosy per se. In the same line, carrier analysis for LTA+80 locus showed association with protection for leprosy per se for allele A carriers (OR=0.78; corrected p-value=0.04). In the haplotype analysis, LTA+80A/LTA+252A/TNF-308G was also associated to protection (OR=0.74; corrected p-value=0.02). From IL10 promoter region analysis, -819C>T SNP was associated with susceptibility to leprosy per se to TT (OR=1.58; p-value=0.05) and CT genotypes (OR=1.36; p=0.05). This association could be confirmed in the carriers analysis for -819T allele (OR=1.40; p-value=0.02 and OR=1.39; corrected pvalue= 0.03). From haplotypic analysis for IL10 ... (Complete abstract click electronic access below)
Orientador: Ana Carla Pereira
Coorientador: Vânia Nieto Brito de Souza
Banca: Cynthia Chester Cardoso
Banca: Maria Sueli Parreira de Arruda
Mestre

Thesis (MSc (Genetics))--University of Stellenbosch, 2006.
Pre-eclampsia is a multisystemic disorder with an incidence of ~6-8% in non-Caucasian women in the Western Cape. Trophoblast invasion is vital for adequate anchorage of the placenta to the uterine wall as well as for the optimisation of utero-placental blood flow in uncomplicated pregnancies. This process is facilitated by the fetal trophoblast cells that digest the extracellular matrix of the uterus by secreting various molecules, including the metalloproteinases (MMP), of which MMP-9 has an increased production during the first trimester. Leptin, an autocrine regulator of MMP-9 secretion, functions via the leptin receptor to prevent over-invasion of maternal tissues. The aim of this study was to investigate the role of the leptin (ob) and leptin receptor (obR) genes in predisposition to pre-eclampsia and involved screening the genes in South African non-Caucasian cohorts and performing statistical analysis to determine whether any variants contributed to the disease profile.

For organisms undergoing a developmental process it is ideal that specific genes are induced and repressed at the correct time and to the correct level in a coordinated manner. The process of meiosis and spore formation (collectively known as sporulation) in Saccharomyces cerevisiae provides a convenient system to elucidate transcriptional mechanisms of gene repression and the contribution such repression mechanisms offer to cells capable of undergoing a developmental process. This thesis focuses on transcriptional repression of sporulation-specific genes during both vegetative/mitotic conditions and sporulation. The fitness contribution of transcriptional repressors that regulate sporulationspecific genes during vegetative growth were investigated considering the similarities between meiosis and mitosis such as DNA replication, chromosome segregation and cytokinesis. Well-characterised sporulation genes of different functions were expressed in vegetative cells and ectopic expression of these genes was found not to be lethal. It was ascertained through strain competition studies that ectopic expression of the genes IME1, SMK1, SPR3 and DIT1 during mitotic growth did not affect cellular fitness. The expression of NDT80 in vegetative cells, however, caused a marked reduction in fitness and cells were also further compromised in the absence of the Sum1p repressor that regulates NDT80 transcription. The role of NDT80 as a transcriptional activator of middle sporulation genes, rather than the over-expression of NDT80 as a protein, caused the reduction of cell viability. Transcriptional regulation of the middle sporulation-specific gene SPR3 by the meiosis-specific Set3p repressor complex was investigated using synchronous sporulation cultures of the W303a/?? strain commonly used for sporulation studies. In a mutant W303a/?? ??set3/??set3 strain, lacking a key component of the Set3p repression complex, the transcription of SPR3 was uncharacteristically expressed at higher levels and derepressed during late sporulation. This SPR3 expression was consistent for both SPR3 transcript and SPR3::lacZ reporter protein studies. This preliminary work will enable future studies, using SPR3 promoter deletions fused to a lacZ reporter, aimed at determining the region of the SPR3 promoter that the Set3p complex may interact with to transcriptionally repress the gene during sporulation.

Errata pasted onto back page. Bibliography: p. 133-149. The RhoGEF activity of PBL is shown to be acting predominantly by the activation of Rho1 and downstream signaling pathways required for contractile ring function during cytokinesis. Genetic evidence suggests this could be through the activation of Diaphanous (an FH protein) to reorganize the actin cytoskeleton, as well as through the activation of Rho-kinase which results in the phosphorylation, and activation of myosin. Highlights a possible role for PBL during contractile ring function at a later stage that previously thought. Genetic interaction screens were employed to identify regulators of PBL activity during cytokinesis. CDK1 was identified genetically as a candidate for regulating PFB activity, but functional studies in vivo showed that this regulation was not by direct phophorylation of the PBK consensus CDK1 suites tested. Further screening has identified other possible components pf PBL signaling pathways, but a role during cytokinesis for these interactors remains to be confirmed. The eye phenotypes described provide ideal systems for the identification of components of PBL signaling pathways in Drosophila. The high level of conservation in the mechanism of cytokinesis from yeast to mammals would also suggest that the identified interactors would most likely represent components of cytokinesis pathways in all eukaryotes.

Santrauka Baigiamojo darbo tema Šunų klubo sąnario displazija genetiniai aspektai Baigiamasis darbas atliktas 2012 - 2014 metais Biologiniu sistemų ir genetinių tyrimų institute, K. Janušausko gyvūnų genetikos laboratorijoje. Baigiamojo darbo kiekis 53 puslapių, 15 paveikslėlių , 8 lentelės. Darbo objektas ir uždaviniai. Išanalizuoti šunų klubo sąnario displazijos paveldimumą . Uždaviniai: išanalizuoti literatūrą apie šunų klubo sąnario displazijos genetinius aspektus , klinikinius požymius , diagnostikos ir gydymo metodus , priežastis, paveldėjimą , įvairių veislių šunų displazijos paplitimą, įvertinti genetinių veiksnių - veislės, amžiaus ir lyties įtaką - šunų klubo sąnario displazijos atsiradimui. Mokslinių tyrimų metodologija. Surinkti ir išanalizuoti literatūrą apie šunų klubo sąnario displazijos paplitimą " Jokovo veterinarijos centras" smulkių gyvūnų klinikoje. Rezultatai ir išvados. 2009 - 2013 metais buvo ištirta 638 šunų, iš kurių 169 nustatyta KDS, tai sudaro 26,5% visų ištirtų šunų. Dažniausiai KDS sirgo Amerikiečių stafordšyro terjerai (66,6%), Bordo dogai (66,6 %), Kaukazo aviganiai (57,1%), Anatolijos Karabašai (50%), Korsikos šuo (50%), Leonbergeriai (50%) ir Rytų Europos aviganiai (50%). Rečiausiai sirgo - Sibiro haskiai (7,1%), Amerikiečių akita (10%), samojedai (10%) ir dobermanai (11,1%). Dažniau KSD pasireikšdavo patelėms (31,5%) nei patinams (26,3%). Pagal pasaulinės organizacijos OFA duomenis, atliktus 1974 - 2012 metais Bordo dogai, senbernarai ir... [toliau žr. visą tekstą]
Summary Topic of Final study thesis Canine hip dysplasia genetic aspects Final work accomplished in the year 2012 – 2014 in Institute of Biology Systems and Genetics, K. Janušauskas Laboratory of Animal Genetics. Volume of Final work 53 page original, 15 pictures, 8 tables. Object and tasks of work. Analyse heredity of canine hip dysplasia. Tasks: analyse literature about canine hip dysplasia genetic aspects, clinical signs, diagnosis and treatment methods, causes, inheritances, prevalence of dysplasia in different breeds of dogs; evaluate influence of genetic factors - breed, age and sex – to occurrence of canine hip dysplasia. Research methodology. Gathering and analysing literature about canine hip dysplasia prevalence in “Jokov veterinary center”. Results and conclusions. During 2009 – 2013 years were examined 638 dogs for hip dysplasia manifestation, of which 169 established HD, accounting for 26,5% of the tested dogs. Mostly HD had the American Staffordshire Terrier (66.6%) Dogue de Bordeaux (66.6%), Caucasian shepherd (57.1%), the Anatolian Shepherd Dog (50%), the Corsican dog (50%), Leonberger (50%) and East European shepherd (50%). Least amount of HD were in - Siberian Huskies (7.1%), American akita (10%), Samoyed (10%) and a Dobermans (11.1%). More often CHD were fixed in bitches (31,5%) than in male dogs (26,3%). Up to 18 months age, hip dysplasia established 26,6%, and over 18 months – 31,8%. According to the global organization of OPA made researches in 1974 - 2... [to full text]

Since the development of molecular biology, in the first half of Twentieth Century, genes and DNA are conceived using several metaphors and conceptual frames: genetic information, a text, a book, a blueprint, a computer program, the destiny of the individual. I have searched and analyzed these conceptual frames in the debate about the patentability of DNA, in particular in the Myriad case (Ass'n for Molecular Pathology v. Myriad Genetics, US Supreme Court). In the arguments against genetic patents there is a prevalence of holistic and nondeterminism metaphors (DNA as the book or the language of life, or as the soul of the individual); in the arguments for genetic patents, the DNA is often conceived as a chemical compound or with deterministic and mechanical metaphors (DNA as a blueprint).

Mice homozygous for the disrupted renal type 11a sodium/phosphate (Na/Pi) cotransporter gene, Npt2, (Npt2 KO) exhibit renal Pi wasting and hypercalciuria, predisposing factors for renal stone formation. We observed that Npt2 KO mice, but not wild-type littermates form renal stones. The renal stones were evident in newborn, weanling and adult mice and composed of calcium (Ca) and Pi. The presence of renal calcification correlated with the absence of Npt2 gene expression and the presence of genes responsible for the synthesis (1alpha-hydroxylase) and catabolism (24-hydroxylase) of 1,25-dihydroxyvitamin D, whose elevated levels contribute to the hypercalciuria and renal calcification in Npt2 KO mice. The renal calcification was associated with increased osteopontin (OPN) mRNA expression and colocalized with OPN, the latter associates with renal stones in vivo and inhibits Ca mineralization in vitro). These data demonstrate that hyperphosphaturia and hypercalciuria, secondary to Npt2 gene disruption, are sufficient for the development of renal calcification.

Thesis (Ph.D.) -- University of Adelaide, Dept. of Cytogenetics and Molecular Genetics, 1999.
Copies of author's previously published articles inserted. Amendments pasted onto back-end paper. Bibliography: leaves 255-286.

Thesis (PhDAgric)--University of Stellenbosch, 2001.
ENGLISH ABSTRACT: Maize is undoubtedly South Africa's most important field crop. The identification of markers and genes for traits of interest is important to sustain the improvement of maize cultivation. Northern corn leaf blight (NClB) is a disease that occurs worldwide and can dramatically reduce yield. A number of single dominant resistance genes have been identified for NClB and some have been mapped. Currently there are no simple PCR markers for any of these resistance genes, making markerassisted selection (MAS) difficult. The aim of this study was to develop PCR markers for the NClB resistance genes Ht1, Ht2, Ht3 and Htn1 in maize. To accomplish this, the AFlP (amplified fragment length polymorphism) technique was first optimised. The results indicated that the Mlul/Msel restriction enzyme combination produces a higher percentage of polymorph isms when compared to the PstllMsel enzyme combination. It was also shown that the enzyme combination plays an important role in the percentage of polymorphic fragments observed, whereas the number of restriction enzymes used in AFlP analysis only significantly affects the total number of fragments scored. Populations segregating for the different resistance genes were not available for this study. Nearly-isogenic lines (Nils) were used in combination with AFlP technology to identify markers that map close to the genes. AFlP markers common in at least two resistant or susceptible lines were cloned and converted to PCR markers. Two commercially available recombinant inbred line (Ril) populations were then used to map the identified markers. For Htn1 fifteen polymorphic fragments were present in both resistant lines. They were selected for sequence specific marker conversion. Seven of the fifteen sequence characterized amplified region (SCAR) markers were polymorphic on the Nil pairs and five mapped to one region of maize chromosome 8.05/06. Twenty-one AFlP markers were identified for Ht1 and four SCAR markers were polymorphic In the Ht1 Nils. Three of these were mapped to chromosome 2.07. Three AFlP markers were identified for Ht2 of which two were converted to SCAR markers. Both SCAR markers were polymorphic on the Ht2 Nils and mapped to chromosome 8.05/06. On the Ht3 NILs, four AFLP markers were identified and two converted SCAR markers and one microsatellite marker (bnlg1666) were polymorphic. One of the SCAR markers and the microsatellite marker were mapped to chromosome 7.04 using a RIL population. This reports the first tentative mapping position for the Ht3 locus. The next step was to determine if a set of marker alleles could be used in a number of Htn 1 resistance lines to identify a common donor region selected by the breeders. Nine markers consisting of five SCAR markers, three converted RFLP markers and one microsatellite marker were used on 16 Htn1 resistant lines. The marker allele of us3 was in 12 of the 16 lines in coupling with Htn1 resistance. Second was the marker us5 in 11 of the 16 lines. Using this data 14 of the 16 lines shared a common introgressed region between the markers us3 and us5. A further common introgressed region between 11 of the inbred lines was found between the markers us14 and asg17. The last aim of this study was to propose a new marker technique that might be more successful than the AFLP technique in the identification of markers closely linked to genes. A new marker approach was identified where a MITE (Hbr) primer was used as an anchor primer in combination with resistance gene analog primers. This was found to be a highly polymorphic marker technique that could be used to identify markers and possibly candidate genes. It is a robust technique, which is affordable since amplifications occur from undigested genomic DNA and the primers mainly amplify fragments from genic regions.
AFRIKAANSE OPSOMMING: Mielies (Zea mays) is ongetwyfeld Suid Afrika se belangrikste lanbou gewas. Vir volgehoue opbrengs verbetering is die identifisering van merkers en gene vir belangrike eienskappe noodsaaklik. Noordelike blaarskroei (NBS) kan opbrengs wesenlik kan beïnvloed. Tans is daar reeds "n aantal enkel weerstandsgene geïdentifiseer, maar geen PKR-merkers is beskikbaar vir merker gebaseerde seleksie nie. Die doelwit van hierdie studie was om PKR-merkers te ontwikkel vir vier enkel weerstands gene (Ht1, Ht2, Ht3 en Htn1) teen NBS in mielies. Om die doelstelling te bereik is die AFLP-tegniek eers geoptimiseer. Op grond van waargenome aantal polimorfismes, was Mlul/Mse/"n beter restriksie ensiem kombinasie as Pstl/Msel. In die studie is ook bewys dat die aantal (meer as twee) restriksie ensieme wat gebruik word slegs die aantal fragmente, en nie die persentasie polimorfismes, wesenlik beïnvloed nie. Geen segregerende populasie was vir die verskillende gene beskikbaar nie. Naby isogeniese lyne (NILe) is daarom in kombinasie met die AFLP-tegniek gebruik om merkers te identifiseer wat naby die gene karteer. Alleenlik polimorfiese merkers wat in ten minste twee weerstand biedende of vatbare lyne voorgekom het, is gekloneer en omgeskakel na PKR-merkers. Daarna is twee kommersiële rekombinante ingeteelde lyn populasies gebruik om die gene te karteer. Vyftien fragmente is gevind wat gekoppel was met die Htn1 weerstand. Sewe van hierdie merkers is omgeskakel in polimorfiese SCAR-merkers waarvan vyf gekarteer is in een gebied op chromosoom 8.05/06. Een-en-twintig AFLP-merkers is geïndentifiseer vir Ht1 en vier is omgeskakel na polimorfiese SCAR-merkers. Drie hiervan is gekarteer op chromosoom 2.07. Drie AFLP-merkers is geïndetifiseer vir Ht2 waarvan 2 omgeskakel is na polimorfiese SCAR-merkers. Altwee hierdie merkers is gekarteer op chromosoom 8.05/06. Op die Ht3 lyne is vier AFLP-merkers geïdentifiseer waarvan twee omgeskakel is na polimorfiese SCAR-merkers. Een mikrosatelliet merker (bnlg1666) is ook gevind wat die selfde polimorfiese patroon wys op die Ht3 lyne. Die mikrosateliet en een van die SCAR-merkers het gekarteer op chromosomale posisie 7.04. Hierdie is die eerste tentatiewe posisie vir die Ht3 lokus. Die volgende stap was om te bepaal of "n stel polimorfiese merker-allele gebruik kan word om die donor DNA-segment te identifiseer wat die plantteiers geselekteer het. Nege PKR-merkers wat bestaan het uit vyf SCAR-merkers, 3 omgeskakelde RFLP merkers en een mikrosateliet is gebruik op 16 Hnt1 weerstandslyne. Us3 was die merker alleel wat in die meeste gevalle gekoppel was met die Htn1 weerstandslyne (12/16). Tweede was die merker us5 (in 11 van die 16 lyne). Uit die data blyk dit dat 14 van die 16 lyne "n donor segment het wat beide merkers us3 en us5 bevat. Merkers us14 en asg17 het in 11 van die 16 bestande lyne saam voorgekom. Die laaste doelstelling van hierdie studie was om "n nuwe tegniek te ontwikkel wat dalk meer suksesvol as AFLPs kan wees om merkers te identifiseer nabyaan gene. "n Nuwe tegniek word voorgestel waar "n MITE (Hbr) inleier gebruik kan word in kombinasie met weerstandgeen-analoog inleiers. Dit is gevind dat hierdie kombinasie van inleiers "n hoogs polimorfiese band patroon gee en dat die merkers ook dalk kandidaat-gene kan wees. Die tegniek is maklik uitvoerbaar, relatief goedkoop en maak gebruik van onverteerde genomiese DNA. Die fragmente wat geamplifiseer word is hoofsaaklik vanaf geenryke areas.

Thesis (MSc)--Stellenbosch University, 2003.
ENGLISH ABSTRACT: With knowledge of the human genome increasing constantly we are continually faced with new and potentially groundbreaking methods for managing, treating and/or identifying diseases and predisposition to diseases and conditions at a genetic level. The human cytochrome P450 (CYP) super-family of genes code for enzymes that can participate in metabolism of drugs and foreign chemicals and in steroid synthesis and metabolism. Mutations in these genes may contribute to clinically relevant diseases. In this study, the effects of mutations within four CYP genes were evaluated in two South African disease groups - variegate porphyria and breast cancer. Variegate porphyria (VP) has an unusually high incidence in South Africa due to the R59W founder mutation in the protoporphyrinogen oxidase (PPOX) gene that causes a disruption in the haem biosynthetic pathway. VP presents with variable clinical symptoms and has a relatively low penetrance. It is expected that environmental factors and modifier genes play a role in the clinical expression of VP. CYP genes are implicated as candidate modifier genes for the expression of VP due to the function they have in metabolising many drugs contraindicated in porphyria patients, and the necessity of haem binding to the apoprotein to produce a functional CYP enzyme. This is the first study to investigate CYPs as possible modifier genes for VP clinical expression. Six CYP polymorphisms (CYPIAlml, CYPIAlm2, CYPIA2 - 734 C>A, CYPIBI 8372 A>C, CYP2D6*3, CYP2D6*4), associated with four CYP loci, were genotyped in a VP population and a suitable control population. The results observed are suggestive of CYPIAlml and CYPIBI playing a role as modifiers for the clinical expression of VP as they were significantly associated (PA and CYPIBI 8372 A>C). This represents the first investigation of the potential role of CYPs as breast cancer risk modifiers in the two South African populations. Significant differences were observed (PC polymorphism in the population of mixed ancestry. Vast differences in allele frequencies were also observed between the two groups of breast cancer populations. These results emphasize the importance of population-based risk assessment when genetic testing and counselling for complex disease susceptibility is offered. The results of this study provide the first evidence suggesting a role for CYPs in modifying the clinical expression of VP and in acting as risk factors for developing breast cancer in a South African population.
AFRIKAANSE OPSOMMING: Met die konstante toename van kennis oor die mensgenoom kom ons voortdurend te staan voor nuwe metodes vir die beheer, behandeling en/of identifikasie van siektes en vatbaarheid vir siektes op 'n genetiese vlak. Die mens sitochroom P450 geensuperfamilie kodeer vir ensieme betrokke in die metabolisme van medisyne en ander chemiese stowwe en steroïed-sintese en -metabolisme. Mutasies in hierdie gene kan 'n bydrae lewer tot kliniese relevante siektes. In hierdie studie is die effek van mutasies in vier sitochroom gene bestudeer in twee Suid-Afrikaanse siekte groepe, variegate porfirie en borskanker. Variegate porfirie (VP) het 'n besonderse hoë frekwensie in Suid-Afrika as gevolg van die R59W stigter-mutasie in die protoporfirinogeen oksidase (PPOX) geen. Hierdie mutasie lei tot 'n versteuring in die heem biosintese padweg. VP presenteer met variërende kliniese simptome en het 'n betreklike lae penetrasie. Daar word vermoed dat omgewingsfaktore en kandidaat modifiserende gene 'n rol speel in die kliniese beeld van VP. Sitochroom P450 gene is geïdentifiseer as kandidaat modifiserende gene as gevolg van hulle rol in die metabolisme van verbode medikasie vir porfirie pasiënte, asook die binding van heem aan die apoproteïen wat noodsaaklik is vir die produksie van funksionele sitochroom P450 ensiem. Hierdie is die eerste studie wat sitochroom P450 gene as moontlike modifiserende gene vir die kliniese uitdrukking van VP ondersoek. Ses sitochroom P450 polimorfismes (CYPIAlml, CYPIAlm2, CYPIA2 -734 C>A, CYPIBI 8372 A>C, CYP2D6*3, CYP2D6*4) is ondersoek in beide 'n VP populasie en 'n geskikte kontrole populasie. Die resultate suggereer 'n rol vir CYPIAlml en CYPIBI in die modifisering van die kliniese uitdrukking van VP aangesien hulle betekenisvolle assosiasie (PA, CYPIBI 8372 A>C). Hierdie studie verteenwordig die eerste ondersoek na die potensiële rol van sitochroom P450s as risiko-modifiserende faktore vir borskanker in die twee populasies. Betekenisvolle verskille (PC polimorfisme in die gemengde herkoms populasie. Beduidende verskille in alleel frekwensies is ook waargeneem tussen die twee borskanker populasies. Hierdie resultate beklemtoon die belangrikheid van populasie gebaseerde risiko-beraming wanneer genetiese toetse en voorligting vir komplekse siekte-vatbaarheid aangebied word. Die resultate van hierdie studie bied die eerste getuienis dat sitochroom P450s 'n rol kan speel in die modifisering van die kliniese beeld van VP en ook kan optree as as risiko faktore vir die ontwikkeling van borskanker in 'n Suid-Afrikaanse populasie.

Oculopharyngeal Muscular Dystrophy (OPMD) is a late-onset dominant/recessive myopathy caused by the expansion of a polyalanine repeat in exon 1 of the PABPN1 gene. The expression of expanded PABPN1 (expPABPN1) triggers the formation of insoluble nuclear aggregates within muscle fiber nuclei of OPMD patients. These aggregates are enriched in poly(A)RNA and sequester molecular chaperones, ubiquitin and proteasome subunits. In addition to these cellular components, we first identified two novel PABPN1 interacting partners, hnRNPA1 and hnRNPA/B that also localized to the insoluble expPABPN1 aggregates. However, only hnRNPA1 was observed in inclusions of OPMD patients' muscle fiber nuclei. Following this finding, we next established the involvement of the ubiquitin-proteasome pathway in the clearance of misfolded expPABPN1 and provided more insights into the beneficial role of molecular chaperones in OPMD. The inhibition of proteasome correlated with an increase in the aggregation of expPABPN1, suggesting a possible proteasome impairment in OPMD. Conversely, the overexpression of Hsp70 and Hsp40 coincided with a decrease in nuclear aggregates concomitant with a reduced cellular toxicity, suggesting the therapeutic potential of manipulating molecular chaperones levels. Finally, we demonstrated that soluble forms of expPABPN1 are the primary toxic species in OPMD. In the presence of endogenous HSPs, a decrease in expPABPN1 aggregation correlated with an increased cellular toxicity. A defect in polyadenylation or ubiquitination significantly increased expPABPN1 solubility and cell death. Using live-cell imaging, we observed that nuclear aggregates prolonged the survival of expPABPN1-expressing cells, which led us to speculate that protein aggregates are subnuclear structures that preserve cellular homeostasis by depleting the expPABPN1 from the nuclear soluble pool. We propose that the polyalanine expansion in expPABPN1 could enable aberrant protein-protein interactions that would compromise the cellular function of nuclear factors and the expression of genes essential for muscle integrity and differentiation. For instance, expPABPN1 might compromise the function of hnRNP proteins and lead to altered mRNA processing and nucleocytoplasmic export, which can be detrimental to the cell.

The Hereditary Spastic Paraplegias (HSP) comprise a group of neurodegenerative diseases characterized by progressive lower limb spasticity. This disease, with a prevalence ranging from 1 to 20 in 100,000 individuals, is currently untreatable. The neuropathological hallmark is axonal degeneration of motor neurons in the corticospinal tract. However, the mechanisms of pathogenesis underlying this neurodegeneration remain poorly understood. Over the last decade, genetic studies of HSP have identified 33 loci including 14 genes. The main objective of this dissertation was to identify and characterize genes in a large North American HSP cohort. Mutation analysis of the two most common genes implicated in HSP, SPG3 and SPG4, led to the detection of nine novel mutations, including an ancestral SPG4 mutation in five French Canadian families. This screen also allowed for the molecular characterization of the p.del436N mutation in SPG3, which suggests a previously unidentified dominant-negative mechanism. Furthermore, a novel deletion in the VPS9 domain of the ALS2 gene was identified in a family with severe infantile onset HSP. In addition, linkage analysis and whole genome scan efforts resulted in the successful mapping of two novel HSP loci, SPG27 and SAX1. SAX1 represents the first locus for autosomal dominant spastic ataxia, a complicated form of HSP, with a common ancestor in Newfoundland. Finally, a positional candidate gene strategy at the SPG8 locus identified three missense mutations in a novel gene encoding strumpellin. Two mutations failed to rescue an axonal phenotype induced by morpholino knock-down of the SPG8 gene in zebrafish. Our efforts to identify and characterize HSP genes determined the underlying genetic cause in 36% of our cohort. These genetic causes include two novel loci and a novel gene. The findings are a major contribution to the characterization of the pathophysiology of HSP and significantly broaden the knowledge in the field of motor neuron disease. Analysis of the 15 known HSP genes suggests a common disease mechanism involving disrupted axonal membrane protein trafficking. Unraveling this mechanism will elucidate the functional maintenance of neurons in the corticospinal tract and will facilitate the development of therapies for HSP and related diseases.