Genetic complexity of FSH receptor function.

The interaction between follicle-stimulating hormone (FSH) and the FSH receptor (FSHR) is essential for normal oogenesis and spermatogenesis. Recently, single-nucleotide polymorphisms (SNPs) have been assigned to the FSHR gene. These give rise to different FSHR haplotypes that modify the action of FSH. In women, FSH sensitivities during the menstrual cycle and different cycle lengths are observed, depending on the FSHR haplotype. Thus, SNPs of the FSHR determine the ovarian response and should, therefore, be considered in controlled ovarian hyperstimulation during assisted-reproduction techniques in women with normal ovarian function. In men, the impact of the FSHR SNPs is unclear. The genetic complexity of FSHR should be considered when studying FSH action. These SNPs are one of the first examples in which genetic changes contribute to fine-tuning the endocrine regulation of reproduction. A rational pharmacogenetic approach that combines FSH dose according to the FSHR haplotype is envisaged.