Genetic Analysis of Hereditary Ataxias in Peru Identifies SCA10 Families with Incomplete Penetrance

The results of clinical and genetic analysis of three Serbian families (pedigrees) with autosomal dominant inheritance, incomplete penetrance and phenotypic features of GEFS+ are presented in this study. Mutation analysis of the SCN1A, SCN1B and GABRG2 genes was performed in all affected and some unaffected members of these three families. Twentysix exons of SCN1A, five exons of SCN1B and nine exons of GABRG2 were individually amplified using primers based on intronic sequence. PCR products were sequenced in both forward and reverse directions. Subsequently, the samples were run and analyzed using 377 DNA automated sequencer. No consanguinity was noticed. The MM and OM family members live in Republic of Srpska while KS family originates from the central Serbia. No mutations of the exons of SCN1A, SCN1B and GABRG2 genes were found in tested subjects. Obligate carriers in MM family (III-1, III-2, and III-4) exhibit variable expressivity or incomplete penetrance rather than proof of polygenetic inheritance. OM pedigree follows autosomal dominant pattern despite reduced penetrance. Bilinear transmission may assume the possibility of multigenetic mode of inheritance in KS family. The fact that all affected members in three Serbian families were negative for mutations in SCN1A, SCN1B and GABRG2 genes strongly supports the hypothesis of significant genetic heterogeneity of GEFS+. Recognizing GEFS+ on clinical grounds contributes to more precise integration of this syndrome into already existing classification of epileptic syndromes.

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P0065DOUBLE MUTATION INHERITANCE IN PATIENTS WITH FOCAL SEGMENTAL GLOMERULOSCLEROSIS AND ALPORT SUNDROME

Nephrology Dialysis Transplantation ◽

10.1093/ndt/gfaa142.p0065 ◽

2020 ◽

Vol 35 (Supplement_3) ◽

Author(s):

Jingyuan Xie

Keyword(s):

Genetic Analysis ◽

Focal Segmental Glomerulosclerosis ◽

Clinical Symptoms ◽

Compound Heterozygous ◽

Incomplete Penetrance ◽

Digenic Inheritance ◽

Segmental Glomerulosclerosis ◽

Whole Exome ◽

The Family ◽

Genetic Pools

Abstract Background and Aims Focal segmental glomerulosclerosis (FSGS) and Alport syndrome (AS) are the leading causes of ESRD globally. FSGS and AS are clinically heterogeneous nephropathies and mainly genetic causes are the mutations in genes expressed in podocytes and glomerular basement membrane (GBM) respectively. A simple Mendelian model fail to explain the genetic control of both nephropathies completely because of the heterogeneous nature and presence of incomplete penetrance. Therefore, here we investigated the possible digenic control of FSGS and AS. Method To detect the double mutational (mono- or di-genic) cause of FSGS and AS, we conducted whole exome sequencing (WES) and panel sequencing in 67 kidney patients during the period of four years (2015 to June 2019). Inclusion criteria was the proband's clinical symptoms confirming the FSGS or AS based on clinical symptoms and renal biopsy. Clinical and genetic analyses were implemented to correlate the phenotypes with genotypes. Results Genetic analysis discovered that 35 out of 67 (52.23%) had genetic cause of selected nephropathies and 24 out of 35 (68.57%) had mutations in COL4A (3,4 & 5) genes and 11 (31.42%) in other genes. Interestingly, we found 7 out of 35 patients (20%) with double mutations (mono- or di-genic) in COL4A3/COL4A4 genes. After the mentioned period, during routine genetic screening, we also found another patient having double mutations in COL4A3 gene. Subsequently, Sanger sequencing confirmed that the identified mutations were co-segregating with the disease(s) in an incomplete penetrance fashion within the family. Lastly, we found 16 mutations in 8 patients having either monogenic or digeneic double mutations in COL4A3 and/or COL4A4 genes. In sum, we found 12 (75%) mutations in COL4A3 and 4 in COL4A4 (25%), and5 probands (62.5%) had compound heterozygous mutations in COL4A3, 1 proband (12.5%) had in COL4A4 and 2 probands (25%) had digenic (COL4A3/COL4A4) mutations. Last of all, among all the mutations, 10 were novel and 6 have been described previously. Conclusion This genetic analysis provides the first evidence for digenic inheritance of FSGS. The nephrologists and clinical geneticists should keep this possibility in mind for the accuracy in diagnosis, disease management and genetic counseling in future. Additionally, we are also adding 10 novel mutations in COL4A3 and COL4A4 genetic pools.

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Clinical characteristics and molecular genetic analysis of a cohort with idiopathic congenital hypogonadism

Journal of Pediatric Endocrinology and Metabolism ◽

10.1515/jpem-2020-0590 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Ayberk Turkyilmaz ◽

Atilla Cayir ◽

Oguzhan Yarali ◽

Erdal Kurnaz ◽

Emine Kartal Baykan ◽

...

Keyword(s):

Genetic Analysis ◽

Rare Variants ◽

Single Gene ◽

Hypogonadotropic Hypogonadism ◽

Molecular Genetic ◽

Molecular Genetic Analysis ◽

Chromosomal Anomalies ◽

Incomplete Penetrance ◽

Hormone Production ◽

Variant Of Uncertain Significance

Abstract Objectives Hypogonadism is defined as inadequate sex hormone production due to defects in the hypothalamic-pituitary-gonadal axis. In recent years, rare single gene defects have been identified in both hypergonadotropic hypogonadism (Hh), and hypogonadotropic hypogonadism (HH) cases with no chromosomal anomalies. The aim of the present study is to investigate the underlying molecular genetic etiology and the genotype-phenotype relationship of a series of patients with Hh and HH. Methods In total, 27 HH and six Hh cases were evaluated. Clinical and laboratory features are extracted from patients’ hospital files. Whole exome sequencing (WES) analysis was performed. Results A total of 27 HH cases (15 female) (mean age: 15.8 ± 2.7 years) and six Hh patients (six females) (mean age: 14.9 ± 1.2 years) were included. In molecular genetic analysis, a pathogenic/likely pathogenic variant was identified in five (two patients from the same family) of 27 HH cases (two novel) and three of the six Hh. In HH group variants (pathogenic, likely pathogenic and variant of uncertain significance) were identified in KISS1R (n=2), PROK2 (n=1), FGFR1 (n=1), HS6ST1 (n=1), GNRH1 (n=1) genes. In the Hh group, splice-site mutations were detected in DCAF17 (n=1) and MCM9 (n=2) genes. Conclusions HH and Hh cases are genetically heterogeneous diseases due to oligogenic inheritance, incomplete penetrance, and variable expressivity. We found rare variants in CHH related genes in half of our HH cases, whereas they classified as pathogenic/likely pathogenic according to ACMG criteria in only about 15% of HH cases. Using advanced genetic analysis methods such as whole-genome sequencing and long-read sequencing may increase the mutation detection rate, which should always be associated with and expert genetic counseling to interpret the data.

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