Objective: Polycystic ovary syndrome (PCOS) is a multigenic disorder, and insulin resistance is one of its hallmark features. Polymorphisms in exon 17 of insulin receptor (INSR) gene are reported to be associated with PCOS. We investigated this association in Indian women and its putative relationship with PCOS associated traits, which has not been explored so far. Methods: In this case control study, the polymorphisms were investigated by direct sequencing in 180 women with PCOS and 144 age matched controls. Clinical, anthropometric, biochemical, and hormonal parameters were also estimated. Results: The silent C/T polymorphism at His1058 in exon 17 of INSR was found to be present in our study population. The polymorphic genotype (CTCTT) was significantly associated with PCOS in lean women (c 2 Z8.493, dfZ1, PZ0.004). It showed association with higher fasting insulin levels (PZ0.02), homeostasis model assessment of insulin resistance (PZ0.005), free androgen index (PZ0.03), and lower quantitative insulin sensitivity check index (PZ0.004) in lean PCOS women. No other novel or known polymorphism was identified in exon 17 in this cohort. Conclusions: The study shows significant association of C/T polymorphism at His1058 of INSR with PCOS in the lean rather than obese Indian women. Its association with indices of insulin resistance and hyperandrogenemia is also seen in the same group. The findings strengthen the concept that pathogenesis of PCOS is different in lean and obese women.

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Our study showed that L55M, but not Q192R, polymorphism is significantly associated with reduced PCOS susceptibility only in lean women and also impacts glucose metabolism, lipid parameters, and hyperandrogenemia in them. Our study therefore suggests the possibility of differential genetic pathophysiology of PCOS between lean and obese women.