Association analysis of FMR1 genetic variants and primary ovarian insufficiency in South Indian women with a novel approach of CGG repeats classification.

Around 20-28% of FMR1gene CGG premutation (PM) carriers are at augmented risk towards an infertility related disorder, Fragile X-associated primary ovarian insufficiency (FXPOI). Except the effect of CGG repeats, reports are not available on the mechanism through which the cis-acting variations, namely, SNPs involved in POI susceptibility. Addressing the hypothesis that the FMR1 gene polymorphisms [CGG repeats, rs25731(T > A) and rs4949(A > G)] might increase their individual and combined impact in disease predisposition, we tested the genetic variants in 200 south Indian DNA samples consists of 100 patients and 100 healthy volunteers. We used gene scan method to score the CGG repeat length, and ARMS and RFLP methods to genotype the SNPs. Only 0.5% of each Gray zone and PM alleles were found among patient group, however, no disease association was noticed with repeat length. The rs25731 showed protection [OR:0.32; (0.13-0.76), p = 0.006] and rs4949 reported a 2.5-fold risk towards the disease predisposition [OR:2.46; (1.06-5.74), p = 0.031] but, both found insignificant after Bonferroni correction was done under different Genetic Models. Novel classification of genotype combinations, 'Normal&Variant Homozygote' [OR:2.89,(1.12-7.9), p < 0.05] and 'Allele2-T-G' haplotype block (6%vs.1%, p = 0.08) were noticed to be at marginal risk for POI. We demonstrated a susceptible role of the combined effect of variant allele-G and Allele-2 (repeat allele outside the normal range) for FXPOI. To support our findings of its first kind, further studies with large samples are warranted in understanding the role of FMR1 genetic variants in FXPOI etio-pathophysiology, the outcome might help in providing better reproductive treatment options for females, who are at risk for FXPOI.

Genetic analysis of an Indian family with members affected with Waardenburg syndrome and Duchenne muscular dystrophy.

PURPOSE: Waardenburg syndrome (WS) is characterized by sensorineural hearing loss and pigmentation defects of the eye, skin, and hair. It is caused by mutations in one of the following genes: PAX3 (paired box 3), MITF (microphthalmia-associated transcription factor), EDNRB (endothelin receptor type B), EDN3 (endothelin 3), SNAI2 (snail homolog 2, Drosophila) and SOX10 (SRY-box containing gene 10). Duchenne muscular dystrophy (DMD) is an X-linked recessive disorder caused by mutations in the DMD gene. The purpose of this study was to identify the genetic causes of WS and DMD in an Indian family with two patients: one affected with WS and DMD, and another one affected with only WS. METHODS: Blood samples were collected from individuals for genomic DNA isolation. To determine the linkage of this family to the eight known WS loci, microsatellite markers were selected from the candidate regions and used to genotype the family. Exon-specific intronic primers for EDN3 were used to amplify and sequence DNA samples from affected individuals to detect mutations. A mutation in DMD was identified by multiplex PCR and multiplex ligation-dependent probe amplification method using exon-specific probes. RESULTS: Pedigree analysis suggested segregation of WS as an autosomal recessive trait in the family. Haplotype analysis suggested linkage of the family to the WS4B (EDN3) locus. DNA sequencing identified a novel missense mutation p.T98M in EDN3. A deletion mutation was identified in DMD. CONCLUSIONS: This study reports a novel missense mutation in EDN3 and a deletion mutation in DMD in the same Indian family. The present study will be helpful in genetic diagnosis of this family and increases the mutation spectrum of EDN3.