Pathogenic variation in insulin resistance genes is common in polycystic ovary syndrome (PCOS): a strategy for causal gene discovery using whole-exome sequencing (WES) in complex traits

Polycystic ovary syndrome (PCOS) is a complex, multi-system, heritable endocrinopathy that is a common cause of anovulatory infertility in reproductive-aged women. While insulin resistance (IR) is not a diagnostic feature, it is widespread in women with PCOS, and often more severe than in women of similar age and BMI. Conversely, women with rare Mendelian disorders of IR also present with features of PCOS. We hypothesize that PCOS is driven by underlying IR, which can be evaluated through a genetic approach. We curated and stratified 310 genes related to three mechanisms of IR using molecular and clinical criteria. We evaluated protein-altering genetic variation in 102 insulin signaling genes, 29 obesity genes, and 22 dyslipidemia genes from whole-exome sequencing data from 675 PCOS patients. 40 insulin signaling genes, 12 obesity genes, and 10 dyslipidemia genes were significantly enriched for protein-altering variation in PCOS cases compared to healthy population controls. Variants in these 62 significantly enriched genes affected 51% of PCOS cases in our study cohort. The 15 highest ranked genes were selected for follow-up: LMNA, LEPR, KCNJ11, BSCL2, ACACA, NTRK2, GCK, ABCC8, SLC2A2, POMC, MC4R, TBC1D4, INSR, NR0B2, and GCKR. 50% of variants identified in these 15 genes were pathogenic, 35% were likely pathogenic, and only 15% were variants of uncertain significance. These findings support IR as a central pathway in PCOS. Furthermore, this study demonstrates that a candidate pathway approach with sufficient pre-processing can successfully identify functionally relevant variants and genes underlying complex traits.