Objectives: To determine whether the number of CAG repeats in the androgen receptor gene is enhanced in patients with idiopathic azoospermia.
Methods: Using the polymerase chain reaction, the number of CAG repeats was assayed in 41 patients with idiopathic azoospermia and in 48 normozoospermic fertile men.
Results: In the control group, the CAG repeat length ranged from 17 to 30 (mean 23.9 +/- 2.9); in the azoospermic group, the CAG repeat length ranged from 20 to 34 (mean 26.5 +/- 3.5). The difference between the two groups was statistically significant (P = 0.0013). None of the men in the control group had a CAG repeat length greater than 31; four of the azoospermic men had 34 CAG repeats.
Conclusions: Results suggest that an increase in the number of CAG repeats in the androgen receptor gene to 31 or greater may be associated with the etiology of at least some cases of idiopathic azoospermia.