Genetic Predisposition to Polycystic Ovary Syndrome, Postpartum Weight Reduction, and Glycemic Changes: A Longitudinal Study in Women With Prior Gestational Diabetes

Could perturbed fetal development of the ovary contribute to the development of polycystic ovary syndrome in later life?

Polycystic ovary syndrome (PCOS) affects around 10% of young women, with adverse consequences on fertility and cardiometabolic outcomes. PCOS appears to result from a genetic predisposition interacting with developmental events during fetal or perinatal life. We hypothesised that PCOS candidate genes might be expressed in the fetal ovary when the stroma develops; mechanistically linking the genetics, fetal origins and adult ovarian phenotype of PCOS. In bovine fetal ovaries (n = 37) of 18 PCOS candidate genes only SUMO1P1 was not expressed. Three patterns of expression were observed: early gestation (FBN3, GATA4, HMGA2, TOX3, DENND1A, LHCGR and FSHB), late gestation (INSR, FSHR, and LHCGR) and throughout gestation (THADA, ERBB4, RAD50, C8H9orf3, YAP1, RAB5B, SUOX and KRR1). A splice variant of FSHB exon 3 was also detected early in the bovine ovaries, but exon 2 was not detected. Three other genes, likely to be related to the PCOS aetiology (AMH, AR and TGFB1I1), were also expressed late in gestation. Significantly within each of the three gene groups, the mRNA levels of many genes were highly correlated with each other, despite, in some instances, being expressed in different cell types. TGFβ is a well-known stimulator of stromal cell replication and collagen synthesis and TGFβ treatment of cultured fetal ovarian stromal cells inhibited the expression of INSR, AR, C8H9orf3 and RAD50 and stimulated the expression of TGFB1I1. In human ovaries (n = 15, < 150 days gestation) many of the same genes as in bovine (FBN3, GATA4, HMGA2, FSHR, DENND1A and LHCGR but not TOX3 or FSHB) were expressed and correlated with each other. With so many relationships between PCOS candidate genes during development of the fetal ovary, including TGFβ and androgen signalling, we suggest that future studies should determine if perturbations of these genes in the fetal ovary can lead to PCOS in later life.

Zinc-Associated Variant in SLC30A8 Gene Interacts With Gestational Weight Gain on Postpartum Glycemic Changes: A Longitudinal Study in Women With Prior Gestational Diabetes Mellitus

Zinc transporter 8 genetic variant SLC30A8 has been associated with postpartum risk of type 2 diabetes among women with gestational diabetes mellitus (GDM). Gestational weight gain is one of the strongest risk factors for postpartum hyperglycemia. We assessed the interaction between type 2 diabetes-associated SLC30A8 rs13266634 and gestational weight gain on 1-5 years of postpartum glycemic changes in 1,071 women with prior GDM in a longitudinal study. Compared with gestation of 26-30 weeks, postpartum levels of fasting glucose, oral glucose tolerance test 2-h glucose, and hemoglobin A_1c (HbA_1c) increased across rs13266634 TT, CT, and CC genotypes in women with excessive gestational weight gain, whereas opposite genetic associations were found in women with inadequate or adequate gestational weight gain. Postpartum changes in fasting glucose per additional copy of the C allele were -0.18, -0.04, and 0.12 mmol/L in women with inadequate, adequate, and excessive gestational weight gain, respectively (P for interaction = 0.002). We also found similar interactions for changes in 2-h glucose and HbA_1c (P for interaction = 0.003 and 0.005, respectively). Our data indicate that gestational weight gain may modify SLC30A8 variant on long-term glycemic changes, highlighting the importance of gestational weight control in the prevention of postpartum hyperglycemia in women with GDM.