Background. The modulatory domain of the human androgen receptor gene contains a polymorphic CAG repeat coding for a polyglutamine tract. The length of the polyglutamine tract is inversely correlated with transcriptional activity of the androgen receptor. As androgens are crucial to spermatogenesis, decreased transcriptional activity of the androgen receptor associated with a long polyglutamine tract could lead to failure in spermatogenesis. Accordingly, long CAG repeats within the normal range have been suggested to be more common in infertile males than in the control population.
Methods. To test this hypothesis, we examined the CAG repeat number of 192 Finnish males with moderate or severe spermatogenic failure and 149 control males.
Results. Our results did not support the hypothesis, the controls harbored slightly longer CAG repeats than the infertile males.
Conclusion. At least in the present study population from Finland, long CAG repeats in the androgen receptor gene do not play a significant role in spermatogenic failure.