OBJECTIVETo study (CAG) n polymorphism of the androgen receptor (AR) gene in responders and non-responders of male volunteers who received testosterone undecanoate intramuscular injection for contraception and to explore the effect of the polymorphism on hormonal male contraception.

METHODSTwenty-nine non-responders and 34 responders were enrolled in this study as a test and a control group respectively. The numbers of CAG sequence repeats were determined by PCR and DNA sequencing, and the effect of (CAG) n polymorphism on hormonal male contraception was analyzed.

RESULTSThe means of CAG repeats of the test and the control group were 23.62 and 22.97, with no significant difference in between (P > 0.05). The short CAG repeats (n < or = 22) constituted 51.7% in the test group and 50% in the control, while the long ones (n > 22) accounted for 48.3% and 50% , respectively. The short and the long group had a similar distribution. No association was found between CAG repeats and sperm concentration. With FSH > 0.2 IU/L, the probability of azoospermia in the long CAG repeat group was 1.5 times that of the short one.

CONCLUSIONCAG repeats in the AR gene presented polymorphism in the subjects, with no significant difference between the responders and non-responders. Further investigation has yet to be performed into the relationship of hormonal male contraception with CAG repeats or other factors.