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 less than or equal to5x10(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.