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Letteratura scientifica selezionata sul tema "Heterozygotes"

Autore: Grafiati

Pubblicato: 4 giugno 2021

Ultima modifica: 21 febbraio 2023

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Articoli di riviste sul tema "Heterozygotes"

1

Wicker, L. S., B. J. Miller, P. A. Fischer, A. Pressey e L. B. Peterson. "Genetic control of diabetes and insulitis in the nonobese diabetic mouse. Pedigree analysis of a diabetic H-2nod/b heterozygote." Journal of Immunology 142, n. 3 (1 febbraio 1989): 781–84. http://dx.doi.org/10.4049/jimmunol.142.3.781.

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Abstract The development of autoimmune type 1 diabetes mellitus in man and the nonobese diabetic (NOD) mouse is greatly influenced by a gene linked to the MHC. Although homozygosity at the NOD MHC is required for a high prevalence of disease, during backcross studies we have found a small number of diabetic H-2nod/b MHC heterozygotes. These diabetic heterozygotes could either represent a crossover event between the MHC and a putative MHC-linked diabetogenic gene or, alternatively, they could indicate that there is a dominant MHC-linked diabetic gene that has low penetrance in the heterozygous state. Pedigree analysis of a diabetic H-2nod/b MHC heterozygote favors the latter hypothesis.

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2

Everse, Stephen J., Thomas Orfeo, Kathleen E. Brummel-Ziedins, Matthew F. Hockin e Kenneth G. Mann. "Predicting Thrombosis in Factor VLeiden Heterozygotes." Blood 112, n. 11 (16 novembre 2008): 1818. http://dx.doi.org/10.1182/blood.v112.11.1818.1818.

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Abstract Factor VLeiden (G1691A;R506Q) is an autosomal dominant allele displaying high prevalence (3–7%) in the United States Caucasian population and a high incidence of venous thrombosis in homozygotes (50% lifetime risk) but reduced penetrance in heterozygote carriers (<10% lifetime risk). Factors that precipitate or suppress the expression of the thrombotic phenotype in factor VLeiden heterozygotes are not well defined except for relatively infrequent instances of coexpression of other thrombophilic risk factors, e.g. the prothrombin G20210A mutant. Our goal is to mathematically evaluate the effect of factor VLeiden on tissue factor-initiated thrombin generation and determine whether concentration variations within the normal range of antithrombin (86–128%), prothrombin (60–140%) or protein C (77–183%) modulate the factor VLeiden effect when all other factor levels are at mean physiologic concentrations. Our mathematical model (Hockin et al. (2002) JBC 277:18322) was extended to incorporate the protein C pathway by including descriptions of thrombin binding to thrombomodulin, activation of protein C and factor Va inactivation by activated protein C. Simulations were conducted with 100% factor V, 50% factor V/50% factor VLeiden (heterozygote), and 100% factor VLeiden (homozygote). Heterozygous expression of factor VLeiden increases the maximum level of thrombin by 25% and the maximum rate of thrombin generation by a factor of 1.6 over that seen with 100% factor V. Homozygous factor VLeiden yields a 2.6-fold increase in maximum rate and a 60% increase in maximum thrombin level compared to 100% factor V. Decreasing the protein C concentration to 77% in a factor VLeiden heterozygote results in a thrombin generation profile with maximum levels and rates comparable to the factor VLeiden homozygote. At 150% protein C, thrombin generation is suppressed to levels similar to those seen with 100% factor V. When the effect of variable prothrombin levels in a factor VLeiden heterozygote is examined, a 60% level of prothrombin decreases the maximum level of thrombin generation below that seen with 100% factor V. When prothrombin levels are at 140% in the factor VLeiden heterozygote, the thrombin generation profile is similar to that observed with 100% factor VLeiden . When the effect of variable antithrombin levels was tested in a factor VLeiden heterozygote, a 14% decrease in antithrombin resulted in maximum thrombin levels approaching those of the factor VLeiden homozygote. In contrast, 128% antithrombin in a factor VLeiden heterozygote resulted in the suppression of thrombin generation to levels consistent with those seen with 100% factor V. Our results predict that the thrombotic effect of heterogenous expression of factor VLeiden can be reduced when prothrombin levels are at the low extreme of the normal range or when antithrombin or protein C levels are at the high extreme of the normal range. Conversely, the thrombotic effect of the heterozygous expression of factor VLeiden is intensified when prothrombin levels are at the high extreme of normal values or when antithrombin or protein C levels at the low extreme of normal. These results may contribute to the understanding of phenotypic variation within factor VLeiden heterozygotes.

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3

Arora, Jatin, Federica Pierini, Paul J. McLaren, Mary Carrington, Jacques Fellay e Tobias L. Lenz. "HLA Heterozygote Advantage against HIV-1 Is Driven by Quantitative and Qualitative Differences in HLA Allele-Specific Peptide Presentation". Molecular Biology and Evolution 37, n. 3 (22 ottobre 2019): 639–50. http://dx.doi.org/10.1093/molbev/msz249.

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Abstract Pathogen-mediated balancing selection is regarded as a key driver of host immunogenetic diversity. A hallmark for balancing selection in humans is the heterozygote advantage at genes of the human leukocyte antigen (HLA), resulting in improved HIV-1 control. However, the actual mechanism of the observed heterozygote advantage is still elusive. HLA heterozygotes may present a broader array of antigenic viral peptides to immune cells, possibly resulting in a more efficient cytotoxic T-cell response. Alternatively, heterozygosity may simply increase the chance to carry the most protective HLA alleles, as individual HLA alleles are known to differ substantially in their association with HIV-1 control. Here, we used data from 6,311 HIV-1-infected individuals to explore the relative contribution of quantitative and qualitative aspects of peptide presentation in HLA heterozygote advantage against HIV. Screening the entire HIV-1 proteome, we observed that heterozygous individuals exhibited a broader array of HIV-1 peptides presented by their HLA class I alleles. In addition, viral load was negatively correlated with the breadth of the HIV-1 peptide repertoire bound by an individual’s HLA variants, particularly at HLA-B. This suggests that heterozygote advantage at HLA-B is at least in part mediated by quantitative peptide presentation. We also observed higher HIV-1 sequence diversity among HLA-B heterozygous individuals, suggesting stronger evolutionary pressure from HLA heterozygosity. However, HLA heterozygotes were also more likely to carry certain HLA alleles, including the highly protective HLA-B*57:01 variant, indicating that HLA heterozygote advantage ultimately results from a combination of quantitative and qualitative effects in antigen presentation.

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4

Falchetti, Alberto, Annamaria Morelli, Andrea Amorosi, Francesco Tonelli, Silvia Fabiani, Valentina Martineti, Roberto Castello, Lino Furlani e Maria Luisa Brandi. "Allelic Loss in Parathyroid Tumors from Individuals Homozygous for Multiple Endocrine Neoplasia Type 11". Journal of Clinical Endocrinology & Metabolism 82, n. 7 (1 luglio 1997): 2278–82. http://dx.doi.org/10.1210/jcem.82.7.4042.

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Homozygosity for the multiple endocrine neoplasia type 1 (MEN1) gene mutation was described in two of three affected siblings of a kindred in which both parents and the third daughter were heterozygotes. Surprisingly, in the two homozygotes, the disease history did not differ from the one of the heterozygotes. In the attempt to unravel genetic differences in parathyroid tumorigenesis between homozygotes and heterozygotes, restriction fragment length polymorphism analysis and microsatellite PCR analysis for loss of heterozygosity (LOH) at the MEN1 gene region on chromosome 11q13 was performed in parathyroid tissues removed at surgery from the mother, her heterozygous sister, and the three siblings. Allelic losses were evidenced in the larger glands of each patient, with a similar pattern of chromosome 11q12–13 losses. The somatic mutation consisted of a large loss of genetic material from chromosome 11. No gross differences exist in the 11q12–13 LOH observed between homozygous and heterozygous carriers. Interestingly, one of the parathyroid tumors from one heterozygote exhibited region of skipped LOH at the 11q12–13 region. The region in the depth of the critical interval retained heterozygosity, whereas those flanking it shared LOH. These findings indicate that inactivation of both copies of the MEN1 gene are not sufficient for parathyroid tumor development in MEN 1 patients and that tumor suppressor genes, other than the MEN1 gene on chromosome 11 or on other chromosomes, can be involved in the pathogenesis of parathyroid tumorigenesis in MEN 1 syndrome.

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5

Dai, K., C. B. Gillies e A. E. Dollin. "Synaptonemal complex analysis of domestic sheep (Ovis aries) with Robertsonian translocations. II. Trivalent and pairing abnormalities in Massey I and Massey II heterozygotes". Genome 37, n. 4 (1 agosto 1994): 679–89. http://dx.doi.org/10.1139/g94-096.

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Zygotene and pachytene spermatocytes from Massey I (t1 5;26) and Massey II (t2 8;11) translocation heterozygotes each contained one trivalent, often delayed in pairing, while cells from double Massey translocation heterozygotes had two such trivalents. As meiosis progressed, trivalents became fully paired, with acrocentric axes in a cis configuration. Abnormal pairing configurations often resulted from interactions between unpaired chromosome axes or segments. However, when two Massey trivalents were present in the same nucleus, there was no pairing interaction between them. In different Massey translocation heterozygotes, trivalent-involved pairing abnormalities occurred in 14–28% of cells, with XY–trivalent and XY–bivalent–trivalent associations being as high as 7.1–23.1%. In spermatocytes from single and double Massey translocation heterozygotes with normal-sized testes, the total SC abnormality frequency was 34.4% for the t1 heterozygotes, 27.1% for the t2 heterozygotes, and 21.4% for the double heterozygote. One Massey II heterozygote with one normal and one small testis had significantly higher SC abnormality frequency (54%) than normal rams. A trisomic cell was recorded in one ram and two hyperdiploid cells in another ram, but these were unrelated to the translocations. It is suggested that resolution of pairing abnormalities by synaptic adjustment is important in reducing the effects on fertility of the translocations.Key words: sheep, Robertsonian translocation, trivalent, abnormal pairing configuration.

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6

Ng, Kevin, Erron W. Titus, Krystien V. Lieve, Thomas M. Roston, Andrea Mazzanti, Frederick H. Deiter, Isabelle Denjoy et al. "An International Multicenter Evaluation of Inheritance Patterns, Arrhythmic Risks, and Underlying Mechanisms of CASQ2 -Catecholaminergic Polymorphic Ventricular Tachycardia". Circulation 142, n. 10 (8 settembre 2020): 932–47. http://dx.doi.org/10.1161/circulationaha.120.045723.

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Background: Genetic variants in calsequestrin-2 ( CASQ2 ) cause an autosomal recessive form of catecholaminergic polymorphic ventricular tachycardia (CPVT), although isolated reports have identified arrhythmic phenotypes among heterozygotes. Improved insight into the inheritance patterns, arrhythmic risks, and molecular mechanisms of CASQ2 -CPVT was sought through an international multicenter collaboration. Methods: Genotype-phenotype segregation in CASQ2 -CPVT families was assessed, and the impact of genotype on arrhythmic risk was evaluated using Cox regression models. Putative dominant CASQ2 missense variants and the established recessive CASQ2-p.R33Q variant were evaluated using oligomerization assays and their locations mapped to a recent CASQ2 filament structure. Results: A total of 112 individuals, including 36 CPVT probands (24 homozygotes/compound heterozygotes and 12 heterozygotes) and 76 family members possessing at least 1 presumed pathogenic CASQ2 variant, were identified. Among CASQ2 homozygotes and compound heterozygotes, clinical penetrance was 97.1% and 26 of 34 (76.5%) individuals had experienced a potentially fatal arrhythmic event with a median age of onset of 7 years (95% CI, 6–11). Fifty-one of 66 CASQ2 heterozygous family members had undergone clinical evaluation, and 17 of 51 (33.3%) met diagnostic criteria for CPVT. Relative to CASQ2 heterozygotes, CASQ2 homozygote/compound heterozygote genotype status in probands was associated with a 3.2-fold (95% CI, 1.3–8.0; P =0.013) increased hazard of a composite of cardiac syncope, aborted cardiac arrest, and sudden cardiac death, but a 38.8-fold (95% CI, 5.6–269.1; P <0.001) increased hazard in genotype-positive family members. In vitro turbidity assays revealed that p.R33Q and all 6 candidate dominant CASQ2 missense variants evaluated exhibited filamentation defects, but only p.R33Q convincingly failed to dimerize. Structural analysis revealed that 3 of these 6 putative dominant negative missense variants localized to an electronegative pocket considered critical for back-to-back binding of dimers. Conclusions: This international multicenter study of CASQ2 -CPVT redefines its heritability and confirms that pathogenic heterozygous CASQ2 variants may manifest with a CPVT phenotype, indicating a need to clinically screen these individuals. A dominant mode of inheritance appears intrinsic to certain missense variants because of their location and function within the CASQ2 filament structure.

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Bonvicino, Cibele R., Paulo S. D'Andrea e Pavel M. Borodin. "Pericentric inversion in natural populations of Oligoryzomys nigripes (Rodentia: Sigmodontinae)". Genome 44, n. 5 (1 ottobre 2001): 791–96. http://dx.doi.org/10.1139/g01-080.

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We analysed polymorphism for pericentric inversion in chromosome 3 of Oligoryzomys nigripes (Rodentia: Sigmodontinae) in several populations in Brazil and examined the meiotic behaviour of this chromosome in heterozygotes. We observed an orderly pairing of all chromosomes at pachytene in heterozygotes for the inverted chromosome 3. No indication of meiotic arrest and germ-cell death was found. Electron microscopy of synaptonemal complexes and conventional meiotic analysis indicated strictly nonhomologous synapsis and crossing-over suppression in the inverted region in the heterozygotes, which prevent the formation of unbalanced gametes. Thus, the pericentric inversion in chromosome 3 does not apparently result in any selective disadvantages in heterozygous carriers. In the majority of the populations studied, the frequencies of acrocentric homozygotes, metacentric homozygotes, and heterozygotes were in HardyWeinberg equilibrium. However, in some populations, we detected an excess of heterozygotes and a deficiency of acrocentric homozygotes.Key words: chromosome rearrangements, inversion, meiosis, Oligoryzomys nigripes.

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Rossi, Enrico, Max K. Bulsara, John K. Olynyk, Digby J. Cullen, Lesa Summerville e Lawrie W. Powell. "Effect of Hemochromatosis Genotype and Lifestyle Factors on Iron and Red Cell Indices in a Community Population". Clinical Chemistry 47, n. 2 (1 febbraio 2001): 202–8. http://dx.doi.org/10.1093/clinchem/47.2.202.

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Abstract Background: Heterozygotes for the C282Y mutation of the HFE gene may have altered hematology indices and higher iron stores than wild-type subjects. Methods: We performed a cross-sectional analysis of 1488 females and 1522 males 20–79 years of age drawn from the Busselton (Australia) population study to assess the effects of HFE genotype, age, gender, and lifestyle on serum iron and hematology indices. Results: Male C282Y heterozygotes had increased transferrin saturation compared with the wild-type genotype. Neither male nor female heterozygotes had significantly increased ferritin values compared with the wild-type genotype. Younger (20–29 years) wild-type males, but not heterozygous males, had significantly lower ferritin values than wild-type males in the older age groups. Compound heterozygous subjects had increased means for serum iron, transferrin saturation, corpuscular volume, and corpuscular hemoglobin compared with the wild-type genotype, and the males also had increased ferritin values (medians 323 vs 177 μg/L; P = 0.003). In both male and female wild-type subjects, an increased body mass index was associated with decreased serum iron and transferrin saturation and increased ferritin values. There was a significant increase in ferritin concentrations in both genders with increasing frequency of red meat consumption above a baseline of 1–2 times per week and alcohol intakes >10 g/day. Conclusions: Male C282Y heterozygotes had significantly increased transferrin saturation values. Compound heterozygous (C282Y/H63D) subjects formed a separate category of C282Y heterozygotes in whom both iron and red cell indices were significantly increased compared with the wild-type genotype.

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Girolami, Antonio, Elisabetta Cosi, Silvia Ferrari, Bruno Girolami e Maria L. Randi. "Thrombotic Events in Homozygotes with a Proven or Highly Probable Arg304Gln Factor VII Mutation (FVII Padua)1): Only Limited Replacement Therapy is Needed in Case of Surgery". Cardiovascular & Hematological Disorders-Drug Targets 19, n. 3 (21 ottobre 2019): 233–38. http://dx.doi.org/10.2174/1871529x19666190308114842.

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Objective: To investigate the prevalence of thrombotic events among patients with proven or highly probable homozygosis for the Arg304Gln (Factor VII Padua) defect or compound heterozygosis containing the Arg304Gln mutation. Methods: Homozygotes and compound heterozygotes proven by molecular studies to have the Arg304Gln mutation were gathered from personal files and from two PubMed searches. In addition, patients with probable homozygosis on the basis of clotting tests (discrepancies among Factor VII activity levels according to the tissue thromboplastin used) were also gathered. Results: 30 proven homozygotes and 17 probable ones were gathered together with 8 compound heterozygotes. In the latter use, the associated mutation was Cys135Arg (twice), Gly180Arg, Arg304Trp, Arg315Trp, His348Gln, Gly365Cys. The prevalence of venous thrombotic events was 16.6, 11.8 and 11.1 percent, respectively for the three groups of patients. Heterozygotes showed no thrombotic event. The difference for proven homozygotes was statistically significant, while for the other groups only a trend was present. Conclusion: proven homozygous or compound heterozygous patients with the Arg304Gln mutation showed a higher than expected incidence of thrombotic events. The same is true for probable cases gathered only on the basis of clotting tests. These patients, because of their frequent lack of bleeding and for their relatively high prevalence of thrombosis should probably receive only limited replacement therapy in case of surgical procedures.

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McClelland, Erin E., Dustin J. Penn e Wayne K. Potts. "Major Histocompatibility Complex Heterozygote Superiority during Coinfection". Infection and Immunity 71, n. 4 (aprile 2003): 2079–86. http://dx.doi.org/10.1128/iai.71.4.2079-2086.2003.

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ABSTRACT Genes of the major histocompatibility complex (MHC) play a critical role in immune recognition, and many alleles confer susceptibility to infectious and autoimmune diseases. How these deleterious alleles persist in populations is controversial. One hypothesis postulates that MHC heterozygote superiority emerges over multiple infections because MHC-mediated resistance is generally dominant and many allele-specific susceptibilities to pathogens will be masked by the resistant allele in heterozygotes. We tested this hypothesis by using experimental coinfections with Salmonella enterica (serovar Typhimurium C5TS) and Theiler's murine encephalomyelitis virus (TMEV) in MHC-congenic mouse strains where one haplotype was resistant to Salmonella and the other was resistant to TMEV. MHC heterozygotes were superior to both homozygotes in 7 out of 8 comparisons (P = 0.0024), and the mean standardized pathogen load of heterozygotes was reduced by 41% over that of homozygotes (P = 0.01). In contrast, no heterozygote superiority was observed when the MHC haplotype combinations had similar susceptibility profiles to the two pathogens. This is the first experimental evidence for MHC heterozygote superiority against multiple pathogens, a mechanism that would contribute to the evolution of MHC diversity and explain the persistence of alleles conferring susceptibility to disease.

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Più fonti

Tesi sul tema "Heterozygotes"

1

GAY, PHILIPPE. "Etude de l'erythropoietine au cours des thalassemies heterozygotes". Aix-Marseille 2, 1992. http://www.theses.fr/1992AIX20193.

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Rowe, Steven M., Cori Daines, Felix C. Ringshausen, Eitan Kerem, John Wilson, Elizabeth Tullis, Nitin Nair et al. "Tezacaftor–Ivacaftor in Residual-Function Heterozygotes with Cystic Fibrosis". MASSACHUSETTS MEDICAL SOC, 2017. http://hdl.handle.net/10150/626280.

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BACKGROUND Cystic fibrosis is an autosomal recessive disease caused by mutations in the CFTR gene that lead to progressive respiratory decline. Some mutant CFTR proteins show residual function and respond to the CFTR potentiator ivacaftor in vitro, whereas ivacaftor alone does not restore activity to Phe508del mutant CFTR. METHODS We conducted a randomized, double-blind, placebo-controlled, phase 3, crossover trial to evaluate the efficacy and safety of ivacaftor alone or in combination with tezacaftor, a CFTR corrector, in 248 patients 12 years of age or older who had cystic fibrosis and were heterozygous for the Phe508del mutation and a CFTR mutation associated with residual CFTR function. Patients were randomly assigned to one of six sequences, each involving two 8-week intervention periods separated by an 8-week washout period. They received tezacaftor-ivacaftor, ivacaftor mono-therapy, or placebo. The primary end point was the absolute change in the percentage of predicted forced expiratory volume in 1 second (FEV1) from the baseline value to the average of the week 4 and week 8 measurements in each intervention period. RESULTS The number of analyzed intervention periods was 162 for tezacaftor-ivacaftor, 157 for ivacaftor alone, and 162 for placebo. The least-squares mean difference versus placebo with respect to the absolute change in the percentage of predicted FEV1 was 6.8 percentage points for tezacaftor-ivacaftor and 4.7 percentage points for ivacaftor alone (P<0.001 for both comparisons). Scores on the respiratory domain of the Cystic Fibrosis Questionnaire-Revised, a quality-of-life measure, also significantly favored the active-treatment groups. The incidence of adverse events was similar across intervention groups; most events were mild or moderate in severity, with no discontinuations of the trial regimen due to adverse events for tezacaftor-ivacaftor and few for ivacaftor alone (1% of patients) and placebo (<1%). CONCLUSIONS CFTR modulator therapy with tezacaftor-ivacaftor or ivacaftor alone was efficacious in patients with cystic fibrosis who were heterozygous for the Phe508del deletion and a CFTR residual-function mutation.

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3

Sousa, Ribeiro Maria Leticia de. "ß-Thalassemia and HB lepore heterozygotes: phenotype-genotype correlation". [Maastricht : Maastricht : Universiteit Maastricht] ; University Library, Maastricht University [Host], 1997. http://arno.unimaas.nl/show.cgi?fid=5822.

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Lebea, Phiyani Justice 1974. "Molecular characterisation of suspected heterozygotes of trimethylaminuria / Phiyani Justice Lebea". Thesis, Potchefstroom University for Christian Higher Education, 2002. http://hdl.handle.net/10394/13595.

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Trimethylaminuria (McKusick 602079) or Fish odour syndrome is inherited recessively as a defect in hepatic nitrogen-oxidation of dietary derived trimethylamine (TMA), which causes excess excretion of trimethylamine such that affected individuals have a body odour reminiscent of rotten fish (Zhang et al., 1995). Trimethylaminuria is a result of either partial or total incapacity to oxygenate trimethylarninuria to its oxide, trimethylamine oxide (TMAO), by an enzyme known as the flavin-containing monooxygenase 3 (FM03). Mutations in the gene of the major human liver enzyme isoform, FM03, are responsible for causing trimethylaminuria (Akerman et al., 1999a and Dolphin et al., 1997b ). Clinical symptoms of this disorder of metabolism include fish-like to garbage-like odour of urine (trimethylaminuria), sweat (ishthyhidrosis) and breath (halitosis) as well as psycho-clinical symptoms such as depression (Akerman et al., l999a). To establish the percentage of homo- and heterozygous trimethylaminuric individuals, a screening programme was introduced for the Potchefstroom first year students. Evaluation of the screening results through the liquid chromatograph-mass spectrometer, which is based on the accurate determination of the TMA:TMAO ratio, showed a 1.46% of mild trimethylaminuria individuals. In this study, clinical symptoms induced by the loading test prior to urine evaluation of the TMA:TMAO ratio is described. This was followed by isolation of the FM03 gene from the blood of suspected individuals and subsequent amplification using the PCR. Amplification was succeeded by restriction fragment length polymorphism analysis for the determination of known common mutations throughout the different exons of the FM03 gene. Single stranded conformation polymorphism and heteroduplex analysis were performed to validate their applicability towards screening the FM03 gene. Preliminary work was also done towards establishing the usage of the denaturing gel gradient gel electrophoresis to screen the FM03 gene for aberrant sequences. xvi Results obtained through restriction fragment length polymorphism indicated the possible presence of the A52T mutation in ex on 3 of both patients that showed symptoms of mild trimethylaminuria. The A52T mutation may be the most prevalent in the South African population although more research still have to be done to investigate this possibility. The main objective of this study was to establish the suitability of different methods towards mutation screening of the FM03 gene. The methods attempted so far include polymerase chain reaction, restriction fragment length polymorphism, single stranded conformation polymorphism, heteroduplex analysis as well as denaturing gradient gel electrophoresis. All methods were applicable, although to different extents and with different limitations and resolutions. This study was a preliminary evaluation for a bigger study, which will include family members of the suspected heterozygotes. In the subsequent study, all nucleotide sequence fragments suspected of having mutations will be sequenced to confirm the presence and the type of the mutation present. xvii
Thesis, MSc, Potchefstroom University for Christian Higher Education 2002.

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5

Jansen, Natalie R. "Comparison of Health-Related Quality of Life Between Heterozygous Women with Fabry Disease, the General Population, and Patients with Chronic Disease". University of Cincinnati / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1109182046.

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6

Skjönsberg, Åsa. "Hereditary susceptibility to inner ear stress agents studied in heterozygotes of the German waltzing guinea pig /". Stockholm, 2006. http://diss.kib.ki.se/2006/91-7140-817-7/.

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7

MARISSAL, CARBONNIER CATHERINE. "Depistage des heterozygotes pour le bloc de la 21 hydroxylase dans une population de femmes adultes hirsutes". Lille 2, 1988. http://www.theses.fr/1988LIL2M001.

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8

Zhang, Mingcai. "The Role of New Mutations in Evolution: Identifying the Deleterious Effect of Heterozygotes and the Beneficial Effect on Adaptation to Salt-Stressed Environments in Drosophila Melanogaster". Bowling Green State University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1276892040.

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9

Yardin, Marie Roseline, of Western Sydney Hawkesbury University, Faculty of Science and Technology e School of Science. "Genetic variation in Anadara trapezia (Sydney cockle) : implications for the recruitment of marine organisms". THESIS_FST_SS_Yardin_M.xml, 1997. http://handle.uws.edu.au:8081/1959.7/56.

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Abstract (sommario):

This project investigated the genetic composition of natural populations of Anadara trapezia in Australia at three spatial scales : i) microgeographic (within an estuary, 50 metres to ~ 6 kilometres); ii) microgeographic (within populations, less than 50 metres); and, iii) macrogeographic (hundreds of kilometres along the coast of Australia). Allozyme polymorphism surveys using cellulose acetate strips have revealed, from 43 enzymes screened, 18 putative polymorphic loci. Comparisons of levels of heterozygosity among enzyme structural groups showed no significant differences, however, monomers were significantly more variable as a group than multimers. Significant differences in the level and distribution of polymorphism among functional groups of enzymes were observed. It appears that selection may be acting at the molecular level, not only on a particular locus, but on a group of functionally similar loci. At the macrogeographic scale, significant departures from random mating were observed in most populations. Significant differences in allele distribution among populations of A. trapezia along the east coast of Australia were found. At the macrogeographic scale, heterogeneity of allele frequencies may depend upon the distance separating the populations and surface water currents. Differentiation among population groups in this study is attributed to changes in the direction of the East Australian Current combined with onshore countercurrents. The systematic status of the disjunct western Australian population of A. trapezia was also evaluated as compared with the east coast populations. No evidence of genetic, hence evolutionary divergence was found. The results have serious implications in the management of fisheries as erroneous assumptions in fisheries management models may lead to depletion and near extinction of marine species. The research stresses the necessity of sampling at multiple scales and replication strategies. It also highlighted the complexities researchers are faced with in studies of marine bivalves, such as the presence of null alleles, deficiencies of heterozygotes, apparent inbreeding and the small geographic scales governing population structure.
Doctor of Philosophy (PhD)

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10

HADJ, SAHRAOUI NADIA. "Processus involutifs affectant les cellules de purkinje au cours du vieillissement chez deux mutants neurologiques : les souris heterozygotes staggerer (+/sg) et reeler (+/rl)". Paris 6, 1996. http://www.theses.fr/1996PA066779.

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La perte des neurones est consideree comme une des principales causes de la deterioration des fonctions du systeme nerveux central au cours du vieillissement. Cependant, les preuves experimentales d'une diminution du nombre des neurones au cours du vieillissement dit normal en particulier chez l'homme peuvent etre sujettes a caution tant a cause des methodes de comptage cellulaire utilisees qu'en raison de pathologies associees non evidentes. Un autre facteur pourrait jouer un role essentiel dans la variabilite des resultats de la litterature a savoir l'heterogeneite genetique des populations etudiees mais ce facteur est pour l'instant difficile a analyser chez l'homme. La souris, mammifere dont la genetique a ete particulierement bien etudiee est l'espece de choix pour mettre a l'epreuve cette hypothese ; nous avons donc quantifie une population de neurones facilement identifiables, les cellules de purkinje du cervelet, chez des mutants neurologiques de la souris pouvant offrir des modeles d'etude du vieillissement neurologique normal. En effet certains mutants neurologiques de la souris tels que staggerer, reeler, pcd (purkinje celle degeneration) presentent a l'etat homozygote des troubles locomoteurs visibles associes a des pertes neuronales massives dans la sphere olivo-cerebelleuse. Par exemple, chez le mutant homozygote staggerer (sg/sg), 60 a 90 % des cellules de purkinje (cp) sont absentes a un mois post-natal, cette perte s'associant a une atrophie macroscopiquement visible du cervelet et a la degenerescence des afferences de ces neurones. Il a ete montre recemment dans notre laboratoire, que l'heterozygote staggerer (+/sg), qui apparait cliniquement sain en apparence et dont le cervelet semble qualitativement normal, presentait cependant une perte de cp se developpant progressivement avec l'age pour atteindre 30 % chez l'animal de 12 mois. Ce resultat a suggere a ses auteurs que le gene staggerer pouvait constituer a l'etat heterozygote un gene de suscept ibilite au vieillissement neurologique normal du cervelet et cette hypothese a ete a l'origine du present travail. Dans un premier temps nous avons analyse l'evolution du nombre des cps chez le +/sg au dela de 12 mois, c'est a dire au cours du vieillissement proprement dit. Notre deuxieme objectif a ete de voir si l'hypothese emise pour le gene staggerer avait une valeur plus generale a savoir si d'autres genes pouvaient etre des genes de susceptibilite pour le vieillissement du cervelet. Nous avons donc etudie un autre exemple de mutant a l'etat heterozygote, le reeler, qui est lui aussi cliniquement sain en apparence. Le nombre des cps a ete estime che des +/sg femelles agees de 13, 18 et 24 mois et des heterozygotes reeler (+/rl) males et femelles de 3, 16 et 26 mois. Dans les deux groupes, les cervelets inclus dans la paraffine ont ete decoupes dans le plan sagittal en coupes seriees. Les cps ont ete comptes toutes les 40 coupes sous un microscope photonique a un grossissment de x1250. Les resultats bruts des comptages cellulaires ont ete corriges selon la methode de hendry. Chez le +/sg de 13 et 18 mois, il y a une diminution significative du nombre de cp (22 a 26 %) par rapport aux temoins (+/+) du meme age. Ce nombre ne change plus chez les +/sg de 13 et 18 mois alors qu'il diminue chez les temoins de 24 mois de maniere identique a celle des +/sg de 13 et 18 mois. Comme les animaux +/+ de la lignee c57bl/6j, les +/+ de la lignee balb/c (temoins des reelers) presentent une perte de cp qui apparait entre 16 et 26 mois et touche environ un quart de la population des cps chez les males. Toujours chez les males, les +/rl presentent un deficit de 16 % du nombre de cp des 3 mois qui atteint 24 % a 16 mois. Chez les femelles en revanche, il n'y a aucune perte de cp significative avec l'age aussi bien chez les sauvages que chez les heterozygotes. Ces resultats confirment donc l'hypothese que le gene staggerer provoque a l'etat heterozygote un vieillissement precoce du cervelet et que cette vulnerabilite des cps se retrouve aussi dans un autre exemple, l'heterozygote reeler. Dans la troisieme partie de notre travail, nous nous sommes demande si les effets de telles mutations se limitaient a la disparition d'un certain pourcentage de cp ou si elles entrainaient egalement des phenomenes involutifs au niveau des cps qui n'etaient pas affectees par le processus de mort neuronale. Nous avons donc recherche des anomalies de la morphologie des cellules de purkinje survivantes chez des heterozygotes staggerer et leur evolution en fonction de l'age. Pour cela nous avons compare la morphologie des arbres dendritiques des cps d'animaux de 4, 12 et 22 mois de +/sg et de +/+ grace a une methode semi-quantitative qui permet d'examiner un grand nombre de cellules en tenant compte de 9 parametres morphologiques decrivant l'arbre dendritique. Il apparait que la mutation staggerer entraine des 4 mois, une involution dendritique tant en largeur qu'en hauteur qui s'ag

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Più fonti

Libri sul tema "Heterozygotes"

1

Tuckerman, Elizabeth M. Studies on the fragile x syndrome with special reference to X-inactivation in female heterozygotes. Birmingham: University of Birmingham, 1988.

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2

Callister, David Rooks. Heterozygosity retained in simulated composite breeds. 1993.

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3

Bright-Thomas, Rowland J., e Andrew M. Jones. Cystic fibrosis. A cura di Patrick Davey e David Sprigings. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780199568741.003.0132.

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Cystic fibrosis is the most common lethal autosomal recessive disorder in Caucasians. There is no known survival advantage of the heterozygote carrier state. Chronic progressive pulmonary infection and bronchiectasis are the major causes of morbidity and mortality. The disease affects all ductal systems where the basic defect is manifest, including the pancreas, gastrointestinal tract, sinuses, hepatobiliary system, and male reproductive system, and has significant effects on nutrition and growth.

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4

Frankham, Richard, Jonathan D. Ballou, Katherine Ralls, Mark D. B. Eldridge, Michele R. Dudash, Charles B. Fenster, Robert C. Lacy e Paul Sunnucks. Inbreeding reduces reproductive fitness. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198783398.003.0003.

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The harmful impacts of inbreeding are generally greater in species that naturally outbreed compared to those in inbreeding species, greater in stressful than benign environments, greater for fitness than peripheral traits, and greater for total fitness compared to its individual components. Inbreeding reduces survival and reproduction (i.e., it causes inbreeding depression), and thereby increases the risk of extinction. Inbreeding depression is due to increased homozygosity for harmful alleles and at loci exhibiting heterozygote advantage. Natural selection may remove (purge) the alleles that cause inbreeding depression, especially following inbreeding or population bottlenecks, but it has limited effects in small populations and usually does not completely eliminate inbreeding depression. Inbreeding depression is nearly universal in sexually reproducing organisms that are diploid or have higher ploidies.

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5

Heidet, Laurence, Bertrand Knebelmann e Marie Claire Gubler. Alport syndrome. A cura di Neil Turner. Oxford University Press, 2015. http://dx.doi.org/10.1093/med/9780199592548.003.0321.

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Alport syndrome is an inherited renal disorder characterized by early haematuria, progressing to proteinuria, sensorineural hearing loss, and progressive renal failure typically in the third or fourth decade but with wide variation. It is responsible for about 1% of end-stage renal failure. Over 80% of cases are X-linked and young men are most affected, but heterozygous carriers of the abnormal gene are also at significantly increased risk of end-stage renal failure in their lifetime. Those affected by the autosomal recessive variant are phenotypically very similar. It is caused by mutations in tissue-specific isoforms of basement membrane (type IV) collagen encoded by COL4A5 (X chromosome), COL4A3, and COL4A4 (chromosome 2).

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6

Pearl, Phillip L., e William P. Welch. Pediatric Neurotransmitter Disorders. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780199937837.003.0059.

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The pediatric neurotransmitter disorders represent an enlarging group of neurological syndromes characterized by inherited abnormalities of neurotransmitter synthesis, metabolism, and transport. Disorders involving monoamine synthesis include guanosine triphosphate cyclohydrolase deficiency (Segawa disease or classical Dopa-responsive dystonia as the heterozygous form), aromatic amino acid decarboxylase deficiency, tyrosine hydrolase deficiency, sepiapterin reductase deficiency, and disorders of tetrahydrobiopterin synthesis. These disorders can be classified according to whether they feature elevated serum levels of phenylalanine. Disorders of γ-amino butyric acid (GABA) metabolism include succinic semialdehyde dehydrogenase deficiency and GABA-transaminase deficiency. Glycine encephalopathy is typically manifested by refractory neonatal seizures due to a defect in the glycine degradative pathway. Pyridoxine-responsive seizures have now been associated with deficiency of α-aminoadipic semialdehyde dehydrogenase as well as a variants requiring therapy with pyridoxal-5-phosphate and folinic acid.

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7

Ehninger, Dan, e Alcino J. Silva. Tuberous Sclerosis and Autism. Oxford University Press, 2013. http://dx.doi.org/10.1093/med/9780199744312.003.0009.

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Tuberous sclerosis (TSC) is a single-gene disorder caused by heterozygous mutations in either the TSC1 or TSC2 genes (Consortium, 1993; van Slegtenhorst et al., 1997). In 70% of cases, TSC gene mutations arise de novo. The remaining 30% of cases are familial with an autosomal dominant pattern of inheritance. Tuberous sclerosis belongs to the group of phakomatoses (neurocutaneous disorders) and is associated with characteristic manifestations in various organ systems, including the brain, skin, kidney, lung, heart, and liver (Crino, Nathanson, & Henske, 2006; Curatolo, Bombardieri & Jozwiak, 2008). Pathological manifestations in these organ systems often include tumor growths or tissue malformations (hamartomas). While penetrance is high, expressivity of TSC phenotypes is highly variable. The birth incidence of TSC is approximately 1:6,000 (Osborne, Fryer, & Webb, 1991). This chapter is an updated and extended version of a previous article on this topic (Ehninger, de Vries, & Silva, 2009)

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8

Heidet, Laurence, Bertrand Knebelmann e Marie Claire Gubler. Alport syndrome. A cura di Neil Turner. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780199592548.003.0322_update_001.

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This chapter describes the clinical features of Alport syndrome. The characteristic features of this familial condition are haematuria with progressive nephropathy and sensorineural hearing loss. Most cases are X-linked so this is typically seen in boys and young men, but female heterozygous (‘carriers’) of X-linked Alport syndrome are also at significant risk of renal disease in their lifetime. The average age of end-stage renal failure is in the third or fourth decade. Those with autosomal recessive disease (approximately 15%) show a similar phenotype. Hearing loss characteristically develops during teenage years or as a young adult, usually as proteinuria becomes prominent and renal function begins to be lost. Angiotensin-converting enzyme inhibitors may modify this classic description. Ocular abnormalities are less consistent and tend to occur later, often after end-stage renal failure. Retinal changes do not affect sight. Lenticonus can be treated by lens replacement. Other ocular abnormalities occur rarely. Aortic disease has been reported in occasional families.

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9

Preconception and Prenatal Carrier Screening for Cystic Fibrosis: Clinical and Laboratory Guidelines. Amer College of Obstetricians &, 2001.

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10

Kriemler, Susi. Exercise, physical activity, and cystic fibrosis. Oxford University Press, 2013. http://dx.doi.org/10.1093/med/9780199232482.003.0033.

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Cystic fibrosis (CF) is the most common genetic autosomal recessive disease of the Caucasian race, generally leading to death in early adulthood.1 The frequency of the gene carrier (heterozygote) is 1:20–25 in Caucasian populations, 1:2000 in African-Americans, and practically non-existent in Asian populations. The disease occurs in about 1 in every 2500 life births of the white population. Mean survival has risen from 8.4 years in 1969 to 32 years in 2000 due to improvements in treatment. The genetic defect causes a pathological electrolyte transport through the cell membranes by a defective chloride channel membrane transport protein [cystic fibrosis transmembrane conductance regulator (CFTR)]. With respect to the function, this affects mainly the exocrine glands of secretory cells, sinuses, lungs, pancreas, liver, and the reproductive tract of the human body leading to a highly viscous, water-depleted secretion. The secretion cannot leave the glands and in consequence causes local inflammation and destruction of various organs. The main symptoms include chronic inflammatory pulmonary disease with a progressive loss of lung function, exocrine and sometimes endocrine pancreas insufficiency, and an excessive salt loss through the sweat glands.1 A summary of the signs and symptoms of CF will be given with a special emphasis on the effect of exercise performance and capacity.

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Capitoli di libri sul tema "Heterozygotes"

1

Scott, D., L. A. Jones, S. A. G. Elyan, A. Spreadborough, R. Cowan e G. Ribiero. "Identification of A-T heterozygotes". In Ataxia-Telangiectasia, 101–16. Berlin, Heidelberg: Springer Berlin Heidelberg, 1993. http://dx.doi.org/10.1007/978-3-642-78278-7_9.

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2

Gr�nfeld, J. P., O. Lidove e F. Barbey. "Heterozygotes with Fabry�s Disease". In Contributions to Nephrology, 208–10. Basel: KARGER, 2001. http://dx.doi.org/10.1159/000060188.

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3

Dallapiccola, B., e B. Porfirio. "Chromosomal Studies in Fanconi Anemia Heterozygotes". In Fanconi Anemia, 145–58. Berlin, Heidelberg: Springer Berlin Heidelberg, 1989. http://dx.doi.org/10.1007/978-3-642-74179-1_12.

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Norman, Amos, e H. Rodney Withers. "Mammography Screening for A-T Heterozygotes". In Ataxia-Telangiectasia, 137–40. Berlin, Heidelberg: Springer Berlin Heidelberg, 1993. http://dx.doi.org/10.1007/978-3-642-78278-7_12.

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5

Kamatani, Naoyuki, Hisashi Yamanaka, Kusuki Nishioka, Yutaro Nishida e Kiyonobu Mikanagi. "Diagnosis of Lesch-Nyhan Heterozygotes by Peripheral Blood". In Purine and Pyrimidine Metabolism in Man V, 157–62. Boston, MA: Springer US, 1986. http://dx.doi.org/10.1007/978-1-4684-5104-7_24.

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6

Sahota, Amrik, Steve Bye, Ju Chen, Nada H. Khattar, Mitchell S. Turker, Fernando Moro, H. Anne Simmonds, Brian T. Emmerson, Ross B. Gordon e J. A. Tischfield. "Molecular Characterization of a Novel Mutation in APRT Heterozygotes". In Purine and Pyrimidine Metabolism in Man VIII, 675–78. Boston, MA: Springer US, 1995. http://dx.doi.org/10.1007/978-1-4615-2584-4_140.

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7

Jordan, G., e J. D. Mollon. "Unique hues in heterozygotes for protan and deutan deficiencies". In Documenta Ophthalmologica Proceedings Series, 67–76. Dordrecht: Springer Netherlands, 1997. http://dx.doi.org/10.1007/978-94-011-5408-6_6.

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8

Paeratakul, Umnarj, e Milton W. Taylor. "Selection and Characterization of APRT Heterozygotes of Mouse L-5178Y Cells". In Purine and Pyrimidine Metabolism in Man V, 253–58. Boston, MA: Springer US, 1986. http://dx.doi.org/10.1007/978-1-4684-5104-7_40.

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9

Shin, Y. S., H. Steigüber, P. Klemm, W. Endres, O. Schwab e G. Wolff. "Branching Enzyme in Erythrocytes. Detection of Type IV Glycogenosis Homozygotes and Heterozygotes". In Studies in Inherited Metabolic Disease, 252–54. Dordrecht: Springer Netherlands, 1988. http://dx.doi.org/10.1007/978-94-009-1259-5_46.

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10

Arnemann, J. "Heterozygotie". In Springer Reference Medizin, 1107–8. Berlin, Heidelberg: Springer Berlin Heidelberg, 2019. http://dx.doi.org/10.1007/978-3-662-48986-4_3499.

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Atti di convegni sul tema "Heterozygotes"

1

Hassan, H. J., L. Cianetti, P. M. Mannucci, V. Vicente, R. Cortese e C. Peschle. "HEREDITARY THROMBOPHILIA CAUSED BY MISSENSE MUTATION IN PROTEIN C GENE". In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1642944.

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The structure of the gene for protein C was analyzed in 13 protein C deficient unrelated patients (11 heterozygous, 2 homozygous), who showed an equivalent reduction of this serine protease at both enzymatic and antigen level. No deletion(s) or rearrangement(s) was demonstrated by Southern blot after hybridization to a cDNA probe. One patient showed a variant restriction pattern after Bam HI digestion, characterized by an abnormal 9.6 kb band in addition to the 8.3 and 1.3 normal ones. Extensive family studies, including 7 heterozygotes with the same clinical phenotype, showed the same abnormal pattern in all and only these heterozygotes. Protein C gene from the propositus was cloned in EMBL3 lambda vector. A 411 bp PstI - SacI fragment from exon 9 encompassing the mutation in the Bam HI site was subcloned in M13mpl8. Its sequence showed a single transversion in the Bam HI palyndrome (GGATCC -> GCATCC) : this causes a substitution of the 402 thryptophan residue with a cystein. The 402 thryptophan residue is constantly conserved in a biochemical domain present in all eukaryotic serine proteases: substitution of the large thryptophan aromatic ring with the small cysteine hydrophilic side-chain conceivably leads to destabilization of the tertiary structure of protein C in these heterozygotes. Thus, the point mutation reported here is sufficient to explain the protein C deficiency in these subjects, and is apparently responsible for their clinical phenotype.

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2

Bounameaux, H., Ph de Moerloose, J. Vogel, G. Reber, B. Krahenbuhl e C. Bouvier. "NORMAL PREGNANCY AND DELIVERY IN A PATIENT WITH SEVERE PROTEIN C DEFICIENCY AND PREVIOUS DEEP-VEIN THROMBOSIS". In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1644312.

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Congenital protein C (PC) deficiency is associated with thrombophilia. Heterozygotes with about half-normal plasma PC levels may present with venous thromboembolic events usually beginning during adolescence or young adulthood. A 26-year-old swiss woman had experienced an iliofemoral deep-vein thrombosis without obvious etiology six years.ago. In June, 1986 very low levels of PC antigen (25 %) and activity (27 %) were found when she was six-month pregnant. Three other family members (62, 24 and 19-year-old) had PC levels around 50 % but were symptomfree. Because of the post-thrombotic~syndrome and the pregnancy, ambulatory heparin therapy was immediately started in the patient (10-16'000 IU twice daily, s.c.) in order to maintain a plasma heparin level between 0.2 and 0.5 U/ml six hs after the morning injection. Delivery was induced at full-term whilst heparin was stopped for a few hours. Four weeks after delivery anticoagulation was discontinued and, so far, the patient remained symptomfree. The newborn showed no perinatal problem and the PC antigen level assayed in the umbilical venous blood was 22 % (normal range in the literature 18-46 %). Antithrombin III and protein S levels as well as fibtinolytic potential were within normal values in all family members.Conclusions. 1) Only one out of four heterozygote PC deficient family members had presented with venous thromboembolism. 2) The symptomatic subject had the lowest PC level in the family (activity and antigen around 25 %). 3) This woman experienced an event-free pregnancy and delivery although heparin was started only in the sixth month of pregnancy. 4) Thus, penetrance of the thrombotic trait may be quite variable (and low) amongst PC deficient heterozygotes, an observation which raises the question of the indication of long-term anticoagulation in these individuals. 5) Pregnancy did not affect the PC antigen and activity levels in our patient.

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3

Borg, J. Y., M. C. Owen, C. Soria, J. Caen e R. W. Carrell. "ANTITHROMBIN ROUEN-I(47 ARG→HIS) AND ROUEN-II (47SER) : TWO NEW VARIANTS WITH DECREASED HEPARIN AFFINITY". In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643679.

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Four families with AT-III variants of decreased heparin affinity have been compared with families with a quantitative deficiency of AT-III. The affinity variants had a lower incidence of thrombosis and, unlike thedefiency variants, had no increase in plasma FDF (defined by anti-D-neo ELISA assay). These results support a major physiological role for the progressive activity of AT-III.The characterisation of the affinity variants provides information onthe heparin-binding site. Variants were isolated from plasma of heterozygotes by NaCl elution gradient from a heparin-Sepharose column. Maps of tryptic and SA V8 peptides were compared on TLC and HPLC with analysis of aberrant peptides. Confirmation was by gas-phase automated sequencing.Two variants were unequivocally identified.1) Rouen-I (47Arg→His) wasfoundin a heterozygote with a history of a single cerebral occlusion.2) Rouen-II (47Arg→Ser) was in a forty years old heterozygote with an acute myocardial infarction but no other history of thrombosis.Three mutations of Arg47 are known: Cys(Toyama), His(Rouen-I) and Se(Rouen-II) all with decreased heparinaffinity.Functional and structural modelling studies are reported indicating apositive heparin-binding site formedby the A and D helices centred on Arg47 (A2). The mutation in Rouen-IIcreates an unutilised oligosaccharide attachment Asn⋆-Arg-Ser suggesting facultative glycosylation. This would, as an incidental observation, support a translational (pre-secretory) origin of the high affinity AT-III beta.

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4

Wautier, J. L., B. Boi zard, Y. Gruel e J. P. Caen. "IMMUNOLOGICAL STUDY OF GLYCOPROTEINS AND ANTIGENS IN GLANZMANN'S THROMBASTHENIA HETEROZYGOTES". In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1644742.

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To further explore the genetic transmission of Glanzmann thrombasthenia (GT) we have conducted a study of platelet glycoproteins and antigens using mono or polyclonal antibodies and cytofluorography. Twenty two members of 4 different families in which at least one member was affected with GT were explored. The reactivity with AP2 (anti GPIIbllla complex), AP3 (anti GPIIIa) antibodies, anti PLA1 and anti Leka was lower than 5% in the platelets of. the 5 patients with GT type I. The 9 obligatory carriers for GT trait were tested with the same technique. The mean value of reactivity expressed as per cent of normal with AP2 and AP3 were 59±11 and 60±12% respectively. The frequency of PLA1 was 0/9 and Leka_ M/9. When both antigens were expressed the amount detectable by cytofluorography was reduced (45-66%). The incidence of Leka_ appeared to be significantly higher from that of a normal population (6.8%). Since PLA1 is located on GPIIIa and Leka on GPIIb the difference on the expression of the two antigens could be secondary to a difference in the ratio GPIIb/GPIIIa in heterozygotes. This could be explained either by an allelic interaction or a linkage between the genes which code for GPIIb and Leka abnormally expressed in GT.

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5

Castaman, G., F. Rodeghiero e M. Ruggeri. "HOMOZYGOUS FACTOR XII CONGENITAL DEFICIENCY: STUDY OF 10 NEW FAMILIES." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643300.

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Sporadic cases of thromboembolic events have been reported in patients with congenital factor XII deficiency and a relationship with a reduced intrinsic fibrinolysis has been suggested.We report here the results of clinical and laboratory investigations in 10 new families comprising 15 homozygotes (age 16-72) and 14 heterozygotes (age 18-65).In homozygotes, kaolin-activated-PTT was indefinitely prolonged and F XII activity and antigen were undetectable, whereas functional assays . of high molecular weight kininogen ahd kallikrein yielded normal values. Intrinsic fibrinolytic activity - assayed on fibrin plate by measuring lysis zones determined i. by euglobulin fraction, obtained in presence of dextran sulphate and flufenamate (Blood activator inventory test, Kluft 1979) - was reduced in all homozygous pts. to about 50% of normal (range 15-70%; normal range 80-120%); normal values were observed in all heterozygotes. Basal extrinsic fibrinolytic activity (measured after addition of Cl-inhibitor) was absent or minimal as in normal controls. None of our patients showed evidence of thrombotic diathesis.In conclusion, our study demonstrates that a reduced intrinsic fibrinolysis, as assayed by blood activator inventory test, is a common finding in F XII deficiency. The absence of thrombotic diathesis in our cases suggests that, this defect is probably devoid of any clinical significance.

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6

Erenso, D., R. Solomon, J. Cooper, G. Welker, E. Aguilar, B. Flanagan, C. Pennycuff et al. "Heterozygotes and Homozygotes Genotypes Human Red Blood Cells Response to Trap and Drag Force". In Bio-Optics: Design and Application. Washington, D.C.: OSA, 2013. http://dx.doi.org/10.1364/boda.2013.jt2a.25.

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Chun, Sehwan, So-Young Bang, Hye-Soon Lee, Sang-Cheol Bae e Kwangwoo Kim. "267 Relative expression strength of HLA-DRB1 in heterozygotes is associated with rheumatic diseases". In 13th International Congress on Systemic Lupus Erythematosus (LUPUS 2019), San Francisco, California, USA, April 5–8, 2019, Abstract Presentations. Lupus Foundation of America, 2019. http://dx.doi.org/10.1136/lupus-2019-lsm.267.

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Zikan, M., O. Dubova, V. Student, P. Koliba, T. Brtnicky e P. Kabele. "824 Double heterozygotes for high penetrance susceptibility genes are not rare and require special care". In ESGO 2021 Congress. BMJ Publishing Group Ltd, 2021. http://dx.doi.org/10.1136/ijgc-2021-esgo.556.

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"Chromosome synapsis and recombination in intraspecific and interspecific heterozygotes for chromosomal rearrangements in voles of the genus Alexandromys". In Bioinformatics of Genome Regulation and Structure/Systems Biology (BGRS/SB-2022) :. Institute of Cytology and Genetics, the Siberian Branch of the Russian Academy of Sciences, 2022. http://dx.doi.org/10.18699/sbb-2022-384.

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Ploos van Amstel, J. K., A. L. van der Zanden, P. H. Reitsma e R. M. Bertina. "RESTRICTION ANALYSIS AND SOUTHERN BLOTTING OF TOTAL HUMAN DNA REVEALS THE EXISTENCE OF MORE THAN ONE GENE HOMOLOGOUS WITH PROTEIN S cDNA". In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1644639.

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A deficiency in protein S, the cofactor of activated protein C, is associated with an increased risk for the development of venous thrombosis. It is inherited as an autosomal dominant disorder. To improve the detection of heterozygotes in affected families, we have started to search for restriction fragment length polymorphism (RFLP) in the protein S gene. This study revealed the existence of two genes containing sequences homologous to protein S cDNA.Three non-overlapping fragments of clone pSUL5, which codes for the carboxy-terminal part of protein S and contains the complete 3' untranslated region, were isolated and used as probes in search for RFLP of the protein S gene.Surprisingly the non-overlapping probes shared more than one hybridizing band. The hybridization took place under stringent assay conditions.This observation is contradictory to the intron-exon organization of a gene and suggests the existence of two genes, containing sequences homologous with pSUL5. Both genes could be assigned to chromosome 3 by mapping through somatic cell hybrids. Whether two functional protein S genes are present in the human genome remains to be established.

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Rapporti di organizzazioni sul tema "Heterozygotes"

1

Moll, Ute M. Risk for Sporadic Breast Cancer in Ataxia Telangiectasia Heterozygotes. Fort Belvoir, VA: Defense Technical Information Center, agosto 2000. http://dx.doi.org/10.21236/ada395438.

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2

Moll, Ute M. Risk for Sporadic Breast Cancer in Ataxia Telangiectasia Heterozygotes. Fort Belvoir, VA: Defense Technical Information Center, agosto 1999. http://dx.doi.org/10.21236/ada393435.

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3

Gao, Qingshen. Susceptibility of BRCA2 Heterozygous Normal Mammary Epithelial Cells to Radiation-Induced Transformation. Fort Belvoir, VA: Defense Technical Information Center, ottobre 2005. http://dx.doi.org/10.21236/ada455086.

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4

Gao, Quingshen. Susceptibility of BRCA2 Heterozygous Normal Mammary Epithelial Cells to Radiation Induced Transformation. Fort Belvoir, VA: Defense Technical Information Center, ottobre 2002. http://dx.doi.org/10.21236/ada412997.

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5

Richmond, Robert C. Cell and Molecular Biology of Ataxia Telangiectasia Heterozygous Human Mammary Epithelial Cells Irradiated in Culture. Fort Belvoir, VA: Defense Technical Information Center, settembre 2002. http://dx.doi.org/10.21236/ada412826.

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6

Smith, Adrian P., John A. Lee e Steven I. Reed. Breast Tumor Kinetics in Mice Overexpressing Cyclin E and Heterozygous for Tumor Suppressor p53 or Rb. Fort Belvoir, VA: Defense Technical Information Center, maggio 2001. http://dx.doi.org/10.21236/ada395709.

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7

Smith, Adrian P., Steven I. Reed e John A. Lee. Breast Tumor Kinetics in Mice Overexpressing Cyclin E and Heterozygous for Tumor Suppressor p53 or Rb. Fort Belvoir, VA: Defense Technical Information Center, maggio 2002. http://dx.doi.org/10.21236/ada407356.

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8

Smith, Adrian P., Steven I. Reed e John A. Lee. Breast Tumor Kinetics in Mice Overexpressing Cyclin E and Heterozygous for Tumor Suppressor p53 or Rb. Fort Belvoir, VA: Defense Technical Information Center, maggio 2003. http://dx.doi.org/10.21236/ada416982.

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9

Kurimasa, Akihiro, Sandeep Burma, Melinda Henrie, Honghai Ouyang, Mitsuhiko Osaki, Hisao Ito, Hatsumi Nagasawa et al. Disruption of NBS1 gene leads to early embryonic lethality in homozygous null mice and induces specific cancer in heterozygous mice. Office of Scientific and Technical Information (OSTI), aprile 2002. http://dx.doi.org/10.2172/943450.

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10

Ginzberg, Idit, Richard E. Veilleux e James G. Tokuhisa. Identification and Allelic Variation of Genes Involved in the Potato Glycoalkaloid Biosynthetic Pathway. United States Department of Agriculture, agosto 2012. http://dx.doi.org/10.32747/2012.7593386.bard.

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Steroidal glycoalkaloids (SGAs) are secondary metabolites being part of the plant defense response. The two major SGAs in cultivated potato (Solanum tuberosum) are α-chaconine and α-solanine, which exhibit strong cellular lytic properties and inhibit acetylcholinesterase activity, and are poisonous at high concentrations for humans. As SGAs are not destroyed during cooking and frying commercial cultivars have been bred to contain low levels, and their content in tubers should not exceed 20 mg/100 g fresh weight. However, environmental factors can increase tuber SGA content above the safe level. The focus of the proposed research was to apply genomic approaches to identify candidate genes that control potato SGA content in order to develop tools for potato improvement by marker-assisted selection and/or transgenic approaches. To this end, the objectives of the proposal included identification of genes, metabolic intermediates and allelic variations in the potato SGAbiosynthetic pathway. The SGAs are biosynthesized by the sterol branch of the mevalonic acid/isoprenoid pathway. Transgenic potato plants that overexpress 3-hydroxy-3-methylglutaryl-CoA reductase 1 (HMG1) or squalene synthase 1 (SQS1), key enzymes of the mevalonic acid/isoprenoid pathway, exhibited elevated levels of solanine and chaconine as well as induced expression of genes downstream the pathway. These results suggest of coordinated regulation of isoprenoid (primary) metabolism and SGA secondary metabolism. The transgenic plants were further used to identify new SGA-related candidate genes by cDNA-AFLP approach and a novel glycosyltransferase was isolated. In addition, genes involved in phytosterol biosynthesis may have dual role and synthesize defense-related steroidal metabolites, such as SGAs, via lanosterol pathway. Potato lanosterol synthase sequence (LAS) was isolated and used to prepare transgenic plants with overexpressing and silencing constructs. Plants are currently being analyzed for SGA content. The dynamics of SGA accumulation in the various organs of a potato species with high SGA content gave insights into the general regulation of SGA abundance. Leaf SGA levels in S. chacoense were 10 to 20-fold greater than those of S. tuberosum. The leptines, SGAs with strong antifeedant properties against Colorado potato beetles, were present in all aerial tissues except for early and mid-developmental stages of above ground stolons, and accounted for the high SGA content of S. chacoense. These results indicate the presence of regulatory mechanisms in most tissues except in stolons that limit the levels of α-solanine and α-chaconine and confine leptine accumulation to the aerial tissues. The genomes of cultivated and wild potato contain a 4-member gene family coding for SQS. Three orthologs were cloned as cDNAs from S. chacoense and heterologously expressed in E. coli. Squalene accumulated in all E. coli lines transformed with each of the three gene constructs. Differential transcript abundance in various organs and amino acid sequence differences in the conserved domains of three isoenzymes indicate subfunctionalization of SQS activity and triterpene/sterol metabolism. Because S. chacoense and S. phureja differ so greatly for presence and accumulation of SGAs, we selected four candidate genes from different points along the biosynthetic pathway to determine if chcor phuspecific alleles were associated with SGA expression in a segregating interspecific diploid population. For two of the four genes (HMG2 and SGT2) F2 plants with chcalleles expressed significantly greater total SGAs compared with heterozygotes and those with phualleles. Although there are other determinants of SGA biosynthesis and composition in potato, the ability of allelic states at two genes to affect SGA levels confirms some of the above transgenic work where chcalleles at two other loci altered SGA expression in Desiree. Present results reveal new opportunities to manipulate triterpene/sterol biosynthesis in more targeted ways with the objective of altering SGA content for both human health concerns and natural pesticide content without disrupting the essential metabolism and function of the phytosterol component of the membranes and the growth regulating brassinosteroids.

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