Parent-of-origin effects on glucose homeostasis in polycystic ovary syndrome

Context: Polycystic ovary syndrome (PCOS) is a highly heritable complex trait. Parents of affected women have reproductive and metabolic phenotypes. Objective: We tested the hypothesis that there are parental effects on the heritability of fasting dysglycemia in women with PCOS. Design and Setting: This was a cross-sectional study at an academic medical center. Participants: Participants included 367 women with PCOS and their parents (1101 total subjects). Main Outcome Measures: We compared maternal and paternal contributions to heritability of fasting dysglycemia and to transmission of the PCOS susceptibility allele of D19S884 within the fibrillin-3 gene (D19S884-A8) on fasting dysglycemia. Results: Fathers had higher fasting glucose levels, prevalence of fasting dysglycemia and proinsulin to insulin molar ratios (P<.0001), a marker of defective insulin processing,comparedwith mothers. Heritability of fasting dysglycemia was significant in PCOS families (h ²=37%, SE=10%, P=.001). Maternal heritability (h² = 51%, SE = 15%, P = .0009) was higher than paternal heritability (h² = 23 %, SE = 23%, P = .186) of fasting dysglycemia after adjustment for age and body mass index. Within dysglycemic probands, there was increased maternal compared with paternal transmission of D19S884-A8 (maternal 84% vs paternal 45%, χ ² = 6.51, P = .011). Conclusions: There was a sex difference in the parental metabolic phenotype with fathers having an increased risk of fasting dysglycemia and evidence for pancreatic β-cell dysfunction compared with mothers. However, only maternal heritability had significant effects on the prevalence of fasting dysglycemia in women with PCOS. Furthermore, there were maternal parent-of-origin effects on transmission of D19S884-A8 probands with fasting dysglycemia. These findings suggest that maternal factors, genetic and perhaps epigenetic, contribute to the metabolic phenotype in affected women.