Effects of the FSH-β-subunit promoter polymorphism -211G->T on the hypothalamic-pituitary-ovarian axis in normally cycling women indicate a gender-specific regulation of gonadotropin secretion.

Abstract

A polymorphism in the FSHB promoter (-211G→T, rs10835638) was found to be associated with decreased FSH, elevated LH, reduced testosterone, and oligozoospermia in males. Although FSH is pivotal for ovarian function, no data on consequences of FSHB -211G→T are available in females. We studied the effects of FSHB -211G→T on the hypothalamic-pituitary-ovarian axis in women. In a university-based in vitro fertilization unit, women undergoing standardized diagnostics were genotyped and compared with a fertile control group. The study group consisted of 365 thoroughly characterized women with normal menstrual cycle intervals and proven ovulation, with predominantly male-factor infertility. The independently recruited control group included 438 women with proven fertility and no history of abortions. Distribution of alleles and genotypes were compared between the study group and controls. In the study group, associations of endocrine parameters with FSHB -211G→T were assessed. Allele and genotype frequencies were not significantly different between the study population and controls (T-allele: 14.4 vs. 16.6%; TT-homozygotes: 2.5 vs. 3.2%). The FSHB -211G→T TT-genotype was strongly associated with elevated FSH (TT-homozygosity effect 2.05 U/liter, P = 0.003). LH increased with the number of T-alleles (1.30 U/liter per T-allele, P < 0.001). Additionally, FSHB -211G→T was associated with reduced progesterone (-1.96 ng/ml per T-allele, P = 0.047). This is a report on phenotypic consequences of FSHB -211G→T on the hypothalamic-pituitary-ovarian axis in women. The findings, partially contradictory to those in men, point to a gender-specific compensatory mechanism of gonadotropin secretion, probably involving progesterone.