Follicle-stimulating hormone receptor gene haplotype distribution in normozoospermic and azoospermic men

The human follicle-stimulating hormone (FSH) receptor (FSHR) gene possesses single nucleotide polymorphisms (SNP) in exon 10, which influence serum FSH levels in women, but not in men. In the present study we extend our previous investigation and for the first time analyze a novel, common SNP at position -29 of the FSHR core promoter in men. The SNP in codon 680 was analyzed in 438 men with nonobstructive azoospermia and in 304 controls. The SNP in codon 307 and at position -29 was analyzed in 345 men with nonobstructive azoospermia and 186 controls. SNPs were determined by allelic discrimination. No significant difference in the frequency of the polymorphism at position 680 and serum FSH levels was found. At position -29 (A/G) the A(-28) allele was less frequent than the G -29 allele both in controls (25% vs 75%) and in patients (30% vs 70%) (P not signficant). Together the three SNPs form four discrete haplotypes (A-Thr-Asn, G-Thr-Asn, A-Ala-Ser, and G-Ala-Ser) occurring in 10 combinations. A statistically significant difference in the allelic distribution between controls and azoospermic men was found (P < .05 by chi(2) test). The A-Ala-Ser allele was more frequent in patients (9.1%) than in controls (5.4%), whereas the G-Thr-Asn allele was less frequent in patients (33.1%) than in controls (40.6%) (P < .01 by Fisher's exact test). No significant correlation between serum FSH levels and FSHR allele was found. We conclude that the FSHR haplotype does not associate with different serum FSH levels but it is differently distributed in normal and azoospermic men. The A-Ala-Ser and the G-Thr-Asn allele might represent genetic factors contributing to phenotypic expression of severe spermatogenetic impairment.