Cag Repeat Number in Androgen Receptor Gene and Male Infertility

Androgens are essential for male sexual development and for fertility. They exert their action through the androgen receptor (AR), a ligandactivated transcription factor. The 5' end of exon 1 of the AR gene includes a polymorphic CAG triplet repeat that varies in number between 10 to 36 in the normal population. There is controversy over an association between high CAG repeat numbers in the AR gene and male infertility. We have evaluated the possible effect of long CAG repeats in the AR on infertility in men from the Republic of Macedonia (R. Macedonia). A group of 222 infertile/subfertile males with different sperm counts and a control group of 152 proven fathers were studied. The CAG repeat number was determined by fluorescent polymerase chain reaction (PCR) amplification of exon 1 of the AR gene analyzed by capillary electrophoresis. Mean CAG length did not differ significantly between males with azoospermia (22.0 ± 3.1), mild oligozoospermia (22.4 ± 2.6), severe oligozoospermia (23.0 ± 4.2), normozoospermia (21.8 ± 2.4), or known causes of infertility (22.1 ± 2.9) and fertile controls (22.3 ± 2.9). However, we found a significantly higher percentage of CAG repeats >26 (p = 0.022), >27 (p = 0.018) and >28 (p = 0.009) in males with mild oligozoospermia. These results indicate a possible association between CAG repeat length and mild oligozoospermia. Further studies on a larger number of patients with mild oligozoospermia are warranted to confirm this association.