Androgen receptor CAG repeat length is associated with ovarian reserve but not with ovarian response

Abstract

The human androgen receptor (AR) gene contains a highly polymorphic CAG repeat sequence within exon 1. In-vitro studies have shown a relationship between CAG repeats in the AR gene and its transactivation potential. This variation in length may play a role in anovulatory infertility. The objective of this study was to investigate whether CAG polymorphism of the AR gene has a predictive value for ovarian reserve, response and cycle outcome in an egg donor programme. CAG length of the AR gene was determined in 147 oocyte donors. All donors underwent ovarian stimulation with a gonadotrophin-releasing hormone antagonist protocol (n = 355). No differences were reported in days of stimulation, gonadotrophin doses, and number of oocytes retrieved. Clinical outcomes were not affected by the CAG repeat length of the AR gene; the primary end-point, antral follicle count, was significantly affected (P < 0.05). In conclusion, in a population of fertile egg donors AR gene CAG polymorphism does not affect ovarian response to gonadotrophins. Antral follicle count was associated with the CAG polymorphism genotype. This suggests that genetic factors may increase susceptibility to poor ovarian reserve, and that AR gene genotype could play a role in the natural ovarian ageing process.

Keywords: CAG polymorphism; androgen receptor; oocyte donor; ovarian reserve; ovarian stimulation.