Loci on chromosome 12q13.2 encompassing ERBB3, PA2G4 and RAB5B are associated with polycystic ovary syndrome

Abstract

Polycystic ovary syndrome (PCOS) is characterized by hyperandrogenemia of ovarian theca cell origin. We report significant association of androgen production with 15 single nucleotide variants (SNVs) identified by exome sequencing of theca cells from women with PCOS and normal ovulatory women. Ten SNVs are located within a 150 kbp region on 12q13.2 which encompasses loci identified in PCOS genome-wide association studies (GWAS) and contains PCOS candidate genes ERBB3 and RAB5B. The region also contains PA2G4 which encodes a transcriptional corepressor of androgen receptor and androgen receptor-regulated genes. PA2G4 has not previously been recognized as related to PCOS in published GWAS studies. Two of the SNVs are predicted to have functional consequences (ERBB3 missense SNV, PA2G4 promoter SNV). PA2G4 interacts with the ERBB3 cytoplasmic domain containing the missense variant, suggesting a potential signaling pathway disruption that could lead to the PCOS ovarian phenotype. Single cell RNA sequencing of theca cells showed significantly less expression of PA2G4 after forskolin treatment in PCOS cells compared to normal cells (padj = 3.82E-30) and in cells heterozygous for the PA2G4 promoter SNV compared to those without the SNV (padj = 2.16E-11). This is consistent with a functional effect of the PA2G4 promoter SNV. No individual SNV was significantly associated with PCOS in an independent family cohort, but a haplotype with minor alleles of three SNVs was found preferentially in women with PCOS. These findings suggest a functional role for 12q13.2 variants in PCOS and implicate variants in ERBB3 and PA2G4 in the pathophysiology of PCOS.