Endocrine Abstracts

Introduction: Polycystic ovary syndrome (PCOS), the most common endocrine disorder in women of reproductive age, is diagnosed based on three criteria, including a polycystic ovarian morphology. Moreover, women with PCOS have elevated serum Anti-Müllerian Hormone (AMH) levels, a hormone known to correlate with follicle number. In addition, AMH production per follicle is suggested to be higher in PCOS. Little is known about AMH gene regulation. Hence, this study aims to investigate the regulation of AMH gene expression in PCOS patients. We have taken a genetic approach through association analysis and performed in silico analysis of common variants in the human AMH promoter. Associated variants were analyzed in vitro to assess the functional impact.

Methods: A cohort of 700 Caucasian PCOS women, diagnosed by the Rotterdam criteria, were included. All common two-allelic single nucleotide polymorphisms (SNPs), located in the region Chr19:2,245,353–2,250,827bp, were selected. AMH levels were measured with the picoAMH assay (Ansh Labs, Houston, Texas, USA) and presented as median (first–third quartile). The association between SNPs and serum AMH levels was analyzed by regression and allele carrier model analyses. KK1 cells were used to assess the functional effects of associated variants.

Results: We assessed 11 SNPs in 700 Caucasian PCOS patients. Polymorphism rs10406324 was associated with AMH levels in the regression analysis. This effect remained present when adjusted for age, BMI, and follicle count (β = –0.52, P = 6.08e-07). Similar results were obtained in a carrier model analysis [AA: n = 645, 8.29 ng/ml (5.20–12.81) vs AG/GG: n = 54/n = 1, 5.57 ng/ml (3.40–9.98), P = 1.47e-03]. Results were replicated in an independent cohort of 321 PCOS patients of European ancestry (P = 2.59e-03 and P = 6.2e-03, respectively). Stratification by BMI in lean (<25 kg/m²) and obese (>30 kg/m²) patients showed that the association was only present in obese PCOS patients [P = 0.01 (AA: n = 162, AG/GG: n = 14)], but not in lean PCOS patients [P = 0.11 (AA: n = 322, AG/GG: n = 22)]. In silico analysis suggested a decreased binding affinity of the transcription factor SF1 to the minor allele G variant. Subsequently, functional analysis showed a significant decrease in basal activity of the AMH promoter construct containing the G variant (P = 0.04), and a lower SF1-induced activity compared to the A variant (P = 8.7e-03).

Conclusion: We have identified a functional AMH promoter polymorphism rs10406324 that is associated with lower serum AMH levels in obese PCOS women. These findings suggest that the genetic context should be taken into consideration when establishing an AMH cutoff value to diagnose PCOS.