AD) 20 ghayes@northwestern.edu (MGH) 21 22 DISCLOSURE STATEMENT: The authors have nothing to disclose. 23 metabolic subtype (KCNH7/FIGN, P=1.0×10 -8 ). We have previously reported that rare 47 variants in DENND1A, a gene regulating androgen biosynthesis, were associated with PCOS 48 quantitative traits in a family-based whole genome sequencing analysis. We classified the 49 reproductive and metabolic subtypes in this family-based PCOS cohort and found that the 50 subtypes tended to cluster in families and that carriers of rare DENND1A variants were 51 significantly more likely to have the reproductive subtype of PCOS. Limitations of our study 52 were that only PCOS cases of European ancestry diagnosed by NIH criteria were included, 53 the sample sizes for the subtype GWAS were small, and the GWAS findings were not 54 replicated. 55 56
Conclusions 57In conclusion, we have found stable reproductive and metabolic subtypes of PCOS. Further, 58 these subtypes were associated with novel susceptibility loci. Our results suggest that these 59 subtypes are biologically relevant since they have distinct genetic architectures. This study 60 demonstrates how precise phenotypic delineation can be more powerful than increases in 61 sample size for genetic association studies. 62
63Understanding the genetic architecture of complex diseases is a central challenge in 64 human genetics (1-3). Often defined according to arbitrary diagnostic criteria, complex 65 diseases can represent the phenotypic convergence of numerous genetic etiologies (4)(5)(6)(7)(8). 66Recent studies in type 2 diabetes support the concept that there are disease subtypes with 67 distinct genetic architecture (7,8). Identifying and addressing genetic heterogeneity in 68 complex diseases could increase power to detect causal variants and improve treatment 69 efficacy (9). 70Polycystic ovary syndrome (PCOS) is a highly heritable, complex genetic disorder 71 affecting up to 15% of reproductive-age women worldwide, depending on the diagnostic 72 criteria applied (10). It is characterized by a variable constellation of reproductive and 73 metabolic abnormalities (Fig 1). It is the leading cause of anovulatory infertility and a major 74 risk factor for type 2 diabetes (T2D) in women (11). Despite these substantial morbidities, 75 the etiology(ies) of PCOS remains unknown (12). Accordingly, the commonly-used 76 diagnostic criteria for PCOS, the National Institutes of Health (NIH) criteria (13) and the 77 Rotterdam criteria (14,15), are based on expert opinion, rather than mechanistic insights, and 78 are designed to account for the diverse phenotypic presentations of PCOS. The NIH criteria 79 require the presence of hyperandrogenism (HA) and chronic oligo/anovulation or ovarian 80 dysfunction (OD) (13). The Rotterdam criteria include polycystic ovarian morphology 81 (PCOM) and require the presence of at least two of these three key reproductive traits, 82 resulting in three different affected phenotypes: HA and OD with or without PCOM, also 83 known as NIH PCOS, as w...