Academic literature on the topic 'Aspetti monogenici'

Monogenic diabetes is frequently mistakenly diagnosed as either type 1 or type 2 diabetes, yet accounts for approximately 1–2% of diabetes. Identifying monogenic forms of diabetes has practical implications for specific therapy, screening of family members and genetic counselling. The most common forms of monogenic diabetes are due to glucokinase ( GCK), hepatocyte nuclear factor ( HNF) -1A and HNF-4A, HNF-1B, m.3243A>G gene defects. Practical aspects of their recognition, diagnosis and management are outlined, particularly as they relate to pregnancy. This knowledge is important for all physicians managing diabetes in pregnancy, given this is a time when previously unrecognised monogenic diabetes may be uncovered with careful attention to atypical features of diabetes misclassified as type 1, type 2, or gestational diabetes.

The paper is dedicated to clinical and laboratory aspects of Diabetes Mellitus non-immune forms, such as neonatal Diabetes Mellitus, Maturity Onset Diabetes of young (MODY), DIDMOAD-syndrome, Wolframe syndrome, Alstrom syndrome and its determinating genes. The analysis of proper clinical results are present in this paper.

The identification of stroke cases caused by monogenic disorders is important both for therapeutic decisions and genetic counselling, although they represent less than 1% of all stroke patients. The purpose of this review is to summarize genetic, pathological, and clinical features of single-gene disorders related to ischemic stroke. The following monogenic disorders are considered: cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy, cerebral autosomal-recessive arteriosclerosis with subcortical infarcts and leukoencephalopathy, hereditary endotheliopathy with retinopathy, nephropathy, and stroke, Fabry disease, pseudoxanthoma elasticum, Neurofibromatosis type 1, familial MoyaMoya disease, Ehlers-Danlos syndrome type IV, Marfan syndrome. For each monogenic disorder, mode of inheritance, pathophysiological aspects, clinical phenotype, and diagnostic tools are carefully described. Furthermore, the classification of monogenetic disorders is presented according to stroke mechanisms, which include small vessel diseases, large artery diseases, and arterial dissections. This review could be useful to identify specific diagnostic pathways for patients with a suspicion of monogenic disease.

The paper presents data on the pathogenesis of systemic lupus erythematosus (SLE), and depicts various molecular mechanisms for the development of SLE and lupus-like syndromes. It describes groups of diseases, such as apoptotic defects; NETosis; interferonopathies; complement deficiency; autotolerance disorders associated with mutations in the RAG1/RAG2 genes; hereditary metabolic diseases (prolidase deficiency, deficiency of adenosine deaminase 2; lysinuric protein intolerance; and α-mannosidase deficiency). The table summarizes clinical data on most of the known lupus-like syndromes and their molecular mechanisms.The pathogenesis of many forms of monogenic lupus-like diseases is being studied. The main sign suggesting in favor of the possible monogenic disease in a patient with SLE is its onset in infancy, especially in males. Attention should be also paid to a compromised family history, including to the marriage between close relatives, the resistance of disease to standard therapy, as well as atypical symptoms.

More and more findings suggest that neurological disorders could have an immunopathological cause. Thus, immune-targeted therapies are increasingly proposed in neurology (even if often controversial), as anakinra, inhibiting IL-1 for febrile inflammatory illnesses, and JAK inhibitors for anti-interferons treatment. Precision medicine in neurology could be fostered by a better understanding of the disease machinery, to develop a rational use of immuno-modulators in clinical trials. In this review, we focus on monogenic disorders with neurological hyper-inflammation/autoimmunity as simplified “models” to correlate immune pathology and targeted treatments. The study of monogenic models yields great advantages for the elucidation of the pathogenic mechanisms that can be reproduced in cellular/animal models, overcoming the limitations of biological samples to study. Moreover, monogenic disorders provide a unique tool to study the mechanisms of neuroinflammatory and autoimmune brain damage, in all their manifestations. The insight of clinical, pathological, and therapeutic aspects of the considered monogenic models can impact knowledge about brain inflammation and can provide useful hints to better understand and cure some neurologic multifactorial disorders.

Autoinflammatory diseases (AIDs) are a family of rare medical entities, characterized by sterile systemic inflammatory episodes caused by exaggerated activation of the innate immune system, for which the pathogenic role of autoantibodies, B or T cells is less relevant. During the past 20 years, a growing number of monogenic inflammatory diseases have been described and their respective responsible genes identified. Proteins encoded by these genes are involved in the regulatory pathways of inflammation and they are mostly expressed in cells of the innate immune system. Since symptoms can overlap within this rapidly expanding disease category, accurate genetic diagnosis is extremely important to start early targeted treatment and to prevent clinically significant or life-threatening complications. On the other hand, detection of more and more genetic variants makes interpretation of results more complicated, and often a genetic diagnosis is not achieved. Thus, the clinical picture represents the starting point for establishing an effective therapy when genetic data are not sufficient or inconclusive. Biologic agents blocking cytokines action have proved to be dramatically effective in a lot of patients.

2013/2014
2013/2014
Le malattie infiammatorie croniche intestinali (MICI), sono un gruppo di malattie eterogenee ad eziologia multifattoriale. Sono caratterizzate da uno stato infiammatorio a carico della mucosa del tratto gastrointestinale e comprendono il Morbo di Crohn (MC), la Rettocolite ulcerosa (RCU) e la Colite indeterminata (CI) i cui quadri istopatologici differiscono tra loro per tipo di lesione, localizzazione della malattia e complicanze associate. Le MICI insorgono tipicamente durante l’adolescenza o in età adulta come il risultato della combinazione di tutti i fattori predisponenti che concorrono in egual misura nella determinazione della malattia. L’insorgenza delle MICI può avvenire anche in età molto precoce, entro i 10 anni ma anche entro i 2 anni e in maniera ancora più grave. In questi casi di esordio precoce si ipotizza che il peso maggiore sia da attribuire alla componente genetica piuttosto che a fattori ambientali e microbici. Solitamente i pazienti con esordio precoce sono caratterizzati da un fenotipo malattia più severo e difficilmente controllabile con le terapie convenzionali. Per gli aspetti differenti che si osservano in termini di predisposizione, caratteristiche fenotipiche, fattori coinvolgenti e geni interessati, le MICI possono essere contestualizzate da una parte come malattie multifattoriali e dall’altra come patologie “monogeniche". Nel contesto della multifattorialità, i numerosi studi di associazione son stati importantissimi in quanto hanno individuato numerosi geni relativi a distinte pathway (barriera intestinale, regolazione dell’immunità innata dell’epitelio, autofagia, sistema fagocitario e stress) coinvolte nella patogenesi delle MICI (ad oggi 163 loci). Nel lavoro di dottorato l’attenzione e l’interesse si è focalizzato sullo studio delle MICI ad insorgenza precoce e uno dei primi obiettivi della tesi è stato quello di indagare in 36 pazienti pediatrici, geni noti dalla letteratura per essere associati alla malattia (NOD2, ATG16L1, IL23R, IL10, IL10RA, IL10RB e XIAP), con il fine di identificare una possibile correlazione genotipo-fenotipo. Anche se non è stato possibile identificare un unico filo conduttore che ci ha permesso di correlare il fenotipo dei pazienti ai genotipi individuati, sono state identificate nuove varianti missenso e introniche. Tutte le varianti individuate sono state analizzate da un punto di vista bioinformatico per valutare la predizione di patogenicità: in base alle predizioni ottenute l’attenzione si è focalizzata su due varianti nel gene NOD2 sulle quali sono stati allestiti saggi funzionali per valutare il loro impatto sulla corretta sintesi e funzionamento della proteina. Un importante dato che emerge sempre più spesso dalla letteratura è l’evidenza che lesioni infiammatorie a carico del tratto gastrointestinale e il fenotipo tipico delle MICI, possono presentarsi molto precocemente (entro i 2 anni di vita) come prime o a volte anche come uniche manifestazioni cliniche in un contesto patologico più ampio che sottende allo sviluppo di gravi immunodeficienze (MICI-like). In questi casi le mutazioni a carico del gene malattia sono molto rare e generalmente considerate come mutazioni “private” e causative del fenotipo malattia che si osserva. Nell’ambito delle MICI in un contesto che possiamo definire monogenico, sono stati analizzati pazienti pediatrici con una sintomatologia MICI-like mediante analisi di sequenza di nuova generazione “Whole Exome Sequencing (WES)”. Sono state ricercate specificamente mutazioni in un determinato set di geni accuratamente selezionati (60 geni) in quanto responsabili di patologie monogeniche che presentano, all’esordio della malattia, una sintomatologia MICI-like. L’obiettivo è quello di riuscire ad effettuare in tempi rapidi l’identificazione di mutazioni in specifici geni malattia, per permettere al clinico di diagnosticare altrettanto rapidamente la malattia e poter intraprendere la terapia più adeguata e specifica per ciascun paziente. Così come sono state individuate numerose varianti presenti nei database e note per la loro associazione alle MICI, sono state identificate anche nuove varianti, mai descritte prima in letteratura. Alcune varianti sono state analizzate con saggi funzionali in vitro in modo da poter comprendere il rispettivo effetto sulla proteina. Per testare l’effetto della variante intronica rs104895421 (c.74-7T>A), situata a monte dell’esone 2 del gene NOD2, è stato allestito il saggio del minigene ibrido. L’esperimento ha messo in evidenza che tale sostituzione nucleotidica altera il corretto funzionamento del meccanismo di splicing, provocando, anche se non con una efficienza del 100% l’esclusione dell’esone. Nel contesto di MICI come malattie monogeniche, sono state individuate due importanti mutazioni, in due pazienti con sintomatologia MICI-like ad esordio molto precoce. La prima è una mutazione, ovvero una delezione di due nucleotidi, identificata nel gene XIAP (c.1021_1022delAA fs p.N341fsX7). Questa delezione determina la sintesi di una proteina tronca provocando un’alterazione strutturale della proteina che ne la funzionalità. Il risultato di tale lavoro ha permesso al clinico di fare finalmente la corretta diagnosi e il paziente è stato curato grazie ad un trapianto di midollo. La seconda mutazione degna di interesse è una mutazione missenso identificata in omozigozi nel gene NOD2 (c.G1277A p.R426H), in seguito all’analisi dell’esoma. Dalle indagini funzionali si evince che tale mutazione altera il normale funzionamento del recettore intracellulare NOD2, e quindi potrebbe spiegare il fenotipo malattia osservato nel giovane paziente (“gain of function”). In questo caso, il confronto con il clinico, in base alle evidenze ottenute dai test eseguiti, deve ancora avere luogo ma sarà di fondamentale importanza per fare una diagnosi e iniziare la terapia idonea. Questa tesi ha incrementato, seppur con piccoli tasselli, le conoscenze riguardo alcuni varianti in geni conosciuti dalla letteratura per la loro associazione con le MICI. I risultati ottenuti hanno avuto inoltre un impatto traslazionale molto importante permettendo ai clinici di fare la corretta diagnosi e iniziare la terapia idonea per migliorare la qualità e l’aspettativa di vita del paziente.
XXVII Ciclo
XXVII Ciclo
1985

Quatre études de liaison génome entier ont mis en évidence une région commune de5,6 Mb dans la région du chromosome 5q15 liée à des traits associés à l’obésité, cette région incluant le gène de la prohormone convertase 1 (PCSK1). Une mutation Pc1 chez la souris a été associée à l’obésité, l’hyperphagie et à une augmentation de l’efficacité du métabolisme. La déficience complète en PCSK1 a été associée à une forme récessive rare d’obésité chezl’homme, et depuis 1997 seuls trois patients présentant cette déficience ont été décrits dans la littérature. Les porteurs de mutations délétères PCSK1 présentent des phénotypes sévères,incluant l’obésité, des hypoglycémies post-prandiales et des problèmes intestinaux ethormonaux. Contrairement aux observations faites chez la souris, les membres des famillesporteurs hétérozygotes ont été considérés comme cliniquement sains. Toutes ces études ontdésigné PCSK1 comme un gène candidat important pour l’obésité.Dans un premier temps, la contribution du gène PCSK1 au risque d’obésitépolygénique a été évaluée chez 13,659 individus d’origine européenne issus de huit cohortescas contrôles ou familiales indépendantes. Neuf variants fréquents couvrant 92% de lavariabilité génétique du locus ont été génotypés. Les méta-analyses des huit études pour levariant commun rs6232 et pour le cluster rs6234-rs6235 ont montré une associationreproductible avec l’obésité chez l’adulte et chez l’enfant (P=7.27x10-8 et P=2.31x10-12respectivement). Le rs6232 était associé à une augmentation du risque d’obésité de 34%, alorsque le cluster rs6234-rs6235 augmentait le risque d’obésité de 22%. Les analysesfonctionnelles ont montré une diminution significative de 10,4% de l’activité catalytique de laprotéine PC1/3 pour le N221D, et une diminution non significative de l’activité catalytique dela protéine PC1/3 pour le cluster Q665E/S690T.L’implication du gène PCSK1 dans l’obésité monogénique a ensuite été entreprise parle séquençage des exons de PCSK1 chez 845 sujets obèses non-consanguins d’origineeuropéenne,. Huit nouvelles mutations non-synonymes ont été identifiées. L’étude des conséquences fonctionnelles des mutations détectées sur la protéine PC1/3 a montré que62.5% de ces mutations détectées étaient prédites délétères par les analyses in silico et 87.5%de ces mutations avaient un effet sur l’auto-activation ou sur l’activité enzymatique de PC1/3in vitro. Dans le but d’estimer le degré de pénétrance pour ces sept mutations pathogéniques,6,060 obèses et 6,274 sujets minces ont été génotypés, démontrant un enrichissement par sixde ces mutations PCSK1 chez les sujets obèses (P=0.007). Cette étude a mis en évidence pourla première fois une augmentation du risque d’obésité chez les porteurs hétérozygotes de mutations perte de fonction du gène PCSK1, confirmant un mode de transmission codominantde l’obésité avec une pénétrance incomplète. La pénétrance de l’obésité a été105estimée à 54.5% pour les porteurs hétérozygotes de mutations délétères PCSK1. Unedéficience partielle en PCSK1 pourrait expliquer environ 0.83% des formes extrêmesd’obésité et représenter la seconde forme la plus fréquente d’obésité monogénique après ladficience en MC4R.Pour conclure, en plus des formes syndromiques très rares d’obésité dues à unedéficience complète en PCSK1, ce travail a permis de démontrer le rôle des variants codantsfréquents non-synonymes dans le risque d’obésité, ainsi que l’importance longtempsinsoupçonné d’une déficience partielle en PCSK1 dans les formes monogéniques d’obésité
Four whole genome studies basing on positional cloning approach revealed a region ofchromosome 5q linked to traits related to obesity, this region contained the gene coding forthe prohormone convertase 1 named PCSK1. Pc1 mutation in mice has been associated withobesity, hyperphagia and increased metabolic efficiency. In human, PCSK1 deficiency is amonogenic form of obesity. The first case of complete PCSK1 deficiency has been identifiedin 1997 and since two other cases were discovered. Deleterious PCSK1 mutations carrierswere either homozygous or compound heterozygous and presented severe phenotypes, such asobesity, intestinal troubles and endocrine disorders. Surprisingly, the family members whowere heterozygous for these mutations appeared clinically unaffected. Overall of these studieshighlighted PCSK1 as a candidate gene for obesity.We have therefore decided to assess the contribution of PCSK1 gene to polygenicobesity risk. To assess the contribution of PCSK1 to polygenic obesity risk, we genotyped tagsingle nucleotide polymorphisms in a total of 13,659 European individuals from eightindependent case-control or family-based cohorts. The non-synonymous variants rs6232,encoding N221D, and cluster rs6234-rs6235, encoding the Q665E-S690T pair, wereconsistently associated with obesity in adults and children (P=7.27 x 10-8 and P=2.31 x 10-12,respectively). Functional analysis revealed a significant impairment of the N221D mutant onPC1/3 protein catalytic activity.In continuity of this study we decided to assess the involvement of PCSK1 gene inmonogenic obesity, knowing that only three cases of complete PCSK1 deficiency have beenreported up to now. The objectives of this study were to evaluate the prevalence of rarePCSK1 mutations contributing to human obesity and to investigate the mode of inheritance ofobesity in the context of PCSK1 deficiency. We sequenced exons of the PCSK1 gene in 845non-consanguineous extremely obese subjects of European origin and we identified eightnovel PCSK1 non-synonymous mutations in eight carriers, all heterozygous. Wecharacterized the functional consequences of the detected mutations on PC1/3 protein and wefound that 62.5% of mutations detected were predicted to be deleterious in silico and werevealed that 87.5% of mutations had an effect on the autoactivation or on the enzymaticactivity of PC1/3 in vitro. In order to estimate the degree of penetrance for the sevenpathogenic mutations, we genotyped 6,060 obese and 6,274 lean subjects. We assessed a 6-fold enrichment of these PCSK1 mutations in obese subjects (P = 0.007). We provided thefirst evidence of an increased obesity risk in heterozygous carriers of loss of functionmutations in PCSK1 gene, confirming a co-dominant mode of transmission of obesity withincomplete penetrance for this gene. The penetrance of obesity was estimated to 54.5% for108heterozygous carriers of deleterious PCSK1 mutations. Partial PCSK1 deficiency mightexplain ~ 0.83% of extreme obesity.To conclude, in addition of the syndromic forms of obesity due to a complete PCSK1deficiency, we provided the strong evidence of the contribution of common non-synonymousvariants in obesity risk and we highlighted that a partial PCSK1 deficiency is associated withan increased risk of obesity

La presbyacousie, surdité neurosensorielle liée à l’âge, est un problème de santé publique majeur dont environ la moitié de la variance phénotypique est d’origine génétique. L’objectif de cette thèse est d’identifier des gènes de presbyacousie par séquençage exomique total. Cette analyse a été effectuée sur 105 familles, 122 cas sporadiques et 120 témoins. L’héritabilité de la presbyacousie était compatible avec une transmission autosomique dominante dans 95% des familles. Des variants très rares, de fréquence allélique mineure (MAF) ≤0,01%, et prédits pathogènes ont été recherchés puis, pour certains, validés. Ce travail dévoile l’importance de l’implication des gènes responsables de surdité précoce dominante chez 23,8% des familles et 27,8% des cas sporadiques contre 9,2% des témoins (p=0,001) dans la presbyacousie avec une majorité de nouveaux variants. L’étude d’un modèle murin Tmc1N321I/N321I a permis d’établir la pathogénie de la mutation p.(Asn327Ile), observée dans une famille atteinte de presbyacousie. La survenue d’une surdité à partir de 7 mois chez les souris Tmc1N321I/+ a validé l’existence d’une forme monogénique de presbyacousie. Un nouveau gène de surdité précoce ou cachée, AP3M2, a été découvert par l’étude des modèles murins Ap3m2ins1/ins1 et Ap3m2L157P/L157P respectivement. Enfin, la Sirtuine 6 semble impliquée dans le maintien de la fonction auditive avec l’âge. Ces travaux révèlent l’existence 1) d’un continuum génétique entre les formes de surdité précoce et la presbyacousie, 2) de formes monogéniques de presbyacousie et 3) de perspectives de thérapies curatives de la presbyacousie telles que la thérapie génique
Presbycusis is a major public health issue worldwide with half of its variance due to genetic predisposition. The aim of this thesis was to identify presbycusis genes by whole exome sequencing (WES). We analysed 105 families, 122 simplex cases and 120 normal hearing controls. After an in silico bioinformatic analysis to select predicted pathogenic variants, and according to the autosomal dominant mode of inheritance in 95% of the families, we looked for very rare heterozygous variants (Minor allele frequency : MAF≤0.0001). We found a significative higher ratio of pathogenic variants in autosomal dominant deafness genes carried by 23,8% of mARHL and 27.8% of sARHL than controls (9,2%) (p=0,001). By studing a mouse model Tmc1N321I, we confirmed the pathogenicity of the mutation leading to congenital moderate hearing loss in homozygous mice due to reduced mechanotransduction current amplitude. The heterozygous mice present a progressive hearing loss beginning at 7 months and affecting first the high frequencies, validating also the mutation as responsible of a monogenic form of presbycusis. We discovered a new deafness gene, AP3M2, responsible of syndomic deafness if deleted and of hidden hearing loss if mutated (p.(Leu157Pro)). Lastly, we proposed Sirtuin 6 as implicated in hair cell function maintenance. WES unraveled that a large proportion of severe presbycusis is due to new mutations in autosomal dominant deafness genes arguing for a genetic continuum between early onset deafness and presbycusis. We demonstrated also the existence of monogenic forms of presbycusis that could be targeted by new personnalized therapies like gene therapy

L'équipe de recherche, au sein de laquelle je réalise ma thèse, s'attache à disséquer les maladies génétiques mendéliennes responsables de pathologies intestinales sévères. L'étude de ces maladies présente deux objectifs. D'une part, étudier au plan moléculaire les mécanismes constituants la barrière intestinale. D'autre part, proposer de nouveaux diagnostics aux patients mais également évaluer de nouvelles cibles thérapeutiques. Ainsi, j'ai participé dans un premier temps à l'étude de données obtenues par séquençage de gênes cibles (Targeted Next Generation Sequencing) au sein d'une cohorte de patients présentant une inflammation intestinale à début précoce (avant 6 ans), afin de rechercher les maladies intestinales monogéniques déjà décrites dans la littérature. En cas de résultat négatif nous réalisions une analyse d'exome (Whole Exome Sequencing) afin d'identifier de nouveaux gênes candidats. La suite de mon travail a consisté à valider au plan fonctionnel la pathogénie des mutations retrouvées dans deux nouveaux gênes. Ainsi, j'ai étudié le mécanisme physiopathologique d'une mutation faux-sens, homozygote sur le gène UNC45A, chez une patiente présentant une diarrhée congénitale sévère néonatale. Puis j'ai validé les conséquences fonctionnelles d'une mutation responsable d'un codon stop précoce sur le gène IPO8. Cette mutation a été retrouvé à l'état homozygote chez un frère et une sœur qui présentaient une inflammation intestinale précoce associées à des symptômes évocateurs d'un syndrome de Loeys-Dietz. Du fait du rôle décrit d'IPO8 dans le transport nucléaire de Smad3, notre objectif a été de mettre en évidence un dysfonctionnement de la voie du TGFbéta chez nos patients
My PhD thesis project is part of the efforts led by our team to dissect Mendelian diseases causing severe intestinal disorders with the scientific goal to get insight into the molecular mechanisms of the human gut barrier and with the medical goal to improve the diagnosis and care of these rare but life-threatening diseases. In the first part of my thesis, I have participated to the analysis of data generated by targeted new generation sequencing or by whole exome sequencing in order to identify known monogenic intestinal disorders and next to identify new candidate genes. In the second part of my thesis, I have led functional studies to validate mutations in two new candidate genes. On the one hand, I am analysing the mechanism of the dramatic congenital diarrheoa observed in a girl carrying an homozygous missense mutation in UNC45, a gene very recently associated with congenital diarrhoea. On the other hand, I am characterizing the functional consequences of a homozygous mutation introducing an early stop codon in IPO8 in two siblings displaying a complex syndrome including intestinal inflammation and symptoms evocative of Loeys-Dietz syndrome. Given previous indication that IPO8 may be involved in the nuclear trafficking of Smad3, we aim at demonstrating impairment of signalling downstream TGFbeta

Certaines maladies héréditaires monogéniques sont caractérisées par une grande hétérogénéité génétique. Chez des individus présentant un phénotype clinique similaire, les mutations causales peuvent être retrouvées dans un des gènes parmi un sous-ensemble décrits comme impliqués dans la maladie. Cette hétérogénéité génétique limite considérablement les offres diagnostiques pour les patients, et une majorité reste sans diagnostic moléculaire. Nous avons développé une approche diagnostique alternative par séquençage à haut débit ciblé (ciblant spécifiquement les régions codantes des gènes d’intérêt par capture d’exons), au travers de trois pathologies génétiquement hétérogènes : le syndrome de Bardet-Biedl (19 gènes décrits), les leucodystrophies (50 gènes), et la déficience intellectuelle (>400 gènes). Au vu de son efficacité dans le syndrome de Bardet-Biedl et la déficience intellectuelle (80% et 25% de mutations détectées respectivement, soit des taux nettement supérieurs à ceux des méthodes précédentes), elle est depuis appliquée en routine diagnostique. Au-delà du diagnostic, cette approche permet de manière non biaisée de revoir la contribution de chacun des gènes dans la pathologie et donc d’identifier les gènes récurrents, et d’établir de nouvelles corrélations génotype/phénotype
Some monogenic disorders are characterized by a vast genetic heterogeneity. In individuals with similar clinical phenotype, causative mutations can be found in one gene from a subset described as implicated in the disease. Such genetic heterogeneity limits considerably the diagnostic offer for the patients, and a majority is left without molecular diagnosis. We developed an alternative diagnostic approach by targeted high throughput sequencing (specific to the coding regions of genes of interest by a technique of exon capture) through three genetically heterogeneous disorders: Bardet-Biedl syndrome (19 genes reported), leukodystrophies (50 genes), and intellectual disability (>400 genes). In light of its efficiency, this approach has since been implemented in diagnostic routine for Bardet-Biedl syndrome and intellectual disability (80% and 25% of diagnostic yields respectively, significantly higher than those of previous methods). Beyond diagnosis, this approach allows unbiased means to assess the contribution of each gene in the disease and highlight recurrent genes, and establish new correlations genotype to phenotype, overall providing much insight in the genetics of a particular disease

Ischaemic stroke is a heterogeneous multifactorial disorder. Although epidemiological data from twin and family studies provide substantial evidence for a genetic basis for stroke, the contribution of genetic factors identified so far is small. Large progress has been made in single-gene disorders associated with ischaemic stroke, particularly at young age. By contrast, little is known about the genes associated with multifactorial stroke. The reported genome-wide association studies of ischaemic stroke have shown that no single common genetic variant imparts major risk, but data on early-onset disease are scarce in this regard. Larger studies with samples numbering in the thousands are ongoing to identify common variants with smaller effects on risk. This approach, in addition with new analytic techniques, will likely contribute to the identification of additional genes, novel pathways, and eventually novel therapeutic approaches to cerebrovascular disorders in the near future. The aims of this review are to summarize data on clinical, genetic, and epidemiologic aspects of monogenic conditions associated with juvenile ischaemic stroke, to discuss recent findings and methodological limitations regarding the genetics of sporadic ischaemic stroke in this age category, and to provide a brief overview of the potential future approaches to stroke genetics.

The glomerular basement membrane (GBM) is a condensed network of extracellular matrix molecules which provides a scaffold and niche to support the function of the overlying glomerular cells. Within the glomerulus, the GBM separates the fenestrated endothelial cells, which line capillary walls from the epithelial cells or podocytes, which cover the outer aspect of the capillaries. In common with basement membranes throughout the body, the GBM contains core components including collagen IV, laminins, nidogens, and heparan sulphate proteoglycans. However, specific isoforms of these proteins are required to maintain the integrity of the glomerular filtration barrier.Across the spectrum of glomerular disease there is alteration in glomerular extracellular matrix (ECM) and a number of histological patterns are recognized. The GBM can be thickened, expanded, split, and irregular; the mesangial matrix may be expanded and glomerulosclerosis represents a widespread accumulation of ECM proteins associated with loss of glomerular function. Whilst histological patterns may follow a sequence or provide diagnostic clues, there remains limited understanding about the mechanisms of ECM regulation and how this tight control is lost in glomerular disease. Monogenic disorders of the GBM including Alport and Pierson syndromes have highlighted the importance of both collagen IV and laminin isoforms and these observations provide important insights into mechanisms of glomerular disease.

This chapter covers all issues of diabetes mellitus in relation to pregnancy. Type 1 and type 2 diabetes are defined, alongside gestational and monogenic diabetes. Advice for the pregnant patient with diabetes is given for every stage, from preconception to ante- and postnatal care. Practical aspects such as target capillary glucose levels, glucose monitoring, and types of insulin are all described. Complications and emergencies, including hypoglycaemia and diabetic ketoacidosis, are also explained, along with their management.

Diabetes that is neither type 1 nor type 2 in aetiology accounts for around 5% of cases, with a wide range of causes. The widest differential diagnosis is in the young adult group. Non-type 1/type 2 diabetes includes monogenic causes of both beta-cell dysfunction (MODY, neonatal diabetes, mitochondrial diabetes) and insulin resistance (lipodystrophy, insulin receptor defects and monogenic obesity), as well as pancreatic, endocrine, and syndromic causes. It is important to make the correct aetiological diagnosis as this is likely to affect treatment and other aspects of management as well as defining the risk of diabetes in family members. Apart from clinical features and basic biochemistry, there are a number of investigations which can help with determining aetiology. These include beta-cell antibodies, assessment of endogenous insulin secretion using C-peptide, specific biomarkers, and genetic testing. Combining some of these features has led to the development of an online probability model for MODY. It is important to understand the roles and limitations of these tests and tools in clinical practice.

Autosomal dominant polycystic kidney disease (ADPKD), the most common monogenic kidney disease, is characterized by relentless development of kidney cysts, hypertension, and eventually end-stage renal disease. The enlargement of the bilateral kidney cysts is gradual throughout the lifetime of the patient until little renal parenchyma is recognizable. At that stage, the average rate of GFR decline is 4.4 to 5.9 mL/min/year. Over the past few years, several advancements in diagnosing, prognosticating, and understanding the pathogenesis of the disease have been made. The natural course of ADPKD makes it an ideal disease to be targeted for renal protection. This chapter discusses various aspects of pathophysiology and molecular pathways and addresses in details the various pharmaceutical and nonpharmaceutical interventions in the journey of prevention of clinical complications of ADPKD.