Androgen receptor gene GGN and CAG polymorphisms among severely oligozoospermic and azoospermic Swedish men.

BACKGROUND We investigated the androgen receptor gene GGN polymorphism and its relation to male infertility and receptor function. METHODS Ninety-nine infertile patients with sperm counts < or = 5 x 10(6)/ml were screened for karyotypic abnormalities and Y-chromosome microdeletions. The GGN and CAG repeats were sequenced in those without genetic abnormalities and in 223 controls. RESULTS Five men (5.1%) carried Y-chromosome microdeletions and five had abnormal karyotypes. Neither the distributions of GGN nor of CAG differed significantly between patients and controls. However, the < 21 CAG and GGN = 23 combination of repeats occurred more frequently in the controls (16%) compared to the entire group of patients (4%; P = 0.003) and to the subgroup of 54 patients with idiopathic infertility (4%; P = 0.02). Testicular volume and CAG lengths were higher (P = 0.04 and 0.002 respectively) among the patients with GGN = 23 compared to GGN = 24. The odds ratio (OR) of having low prostatic secretory function was higher among patients with GGN = 24 than those with GGN = 23 (OR: 3.5; 95% CI: 1.1-11.7; P = 0.04). CONCLUSIONS The < 21 CAG and GGN = 23 combination of repeats may confer a lower risk of infertility to the carriers. Androgen sensitivity may be higher among carriers of the GGN = 23 allele compared to the GGN = 24 allele.