The Role of Epistasis in the Etiology of Polycystic Ovary Syndrome among Indian Women: SNP-SNP and SNP-Environment Interactions

Polycystic Ovary Syndrome (PCOS) is the most common endocrinopathy in women of reproductive age. It is a heterogeneous androgen excess disorder determined by the interaction of multiple genetic and environmental factors. Our earlier analysis on a panel of six candidate genes (Androgen receptor CAG repeats, Follistatin, Luteinizing hormone beta subunit, Calpain10, Insulin receptor substrate-1 and PPAR.) based on 250 PCOS cases and 299 controls revealed significant association patterns with PCOS among South-Indian women. We report here for the first time, the SNP-SNP and SNP-environment interactions of these genes in the same cohort. Both multivariate logistic regression as well as epistasis analysis (using Multifactor dimensionality reduction software) yielded significant results (P < 0.05). All CAPN10 SNPs show association (either risk-conferring or protective) in the obese group, highlighting the importance of this gene in the PCOS pathophysiology. LHP7(LH beta) and UCSNP44(CAPN10) emerged to be the prominent SNPs in the SNP-SNP interaction analysis. The best SNP-SNP interaction model was obtained between CAPN10 UCSNP-44 and PPAR. His447His, implying a significant metabolic component in the PCOS pathology. Replicating our findings in BMI-specific cohorts in different ethnic populations would be warranted in future to identify the physiological networks in PCOS.