Polymorphic CAG repeats of the androgen receptor gene in Japanese male patients with ankylosing spondylitis

Objective. In view of a possible role of androgens in the pathogenesis of a nkylosing spondylitis (AS), we investigated the association between Japanes e male patients with BS and CAG microsatellites of the androgen receptor (A R) gene which related to the AR transactivation function. Methods. Peripheral blood was collected from 39 men with AS and 305 male co ntrol subjects. The number of CAG repeats in exon 1 of the AR gene was dete rmined. Results. CAG repeat lengths in AS patients were significantly shorter than those in the controls (median value 22 vs 23; P = 0.03). However, there was no significant difference in CAG repeats between HLA-B27-positive and -neg ative patients (median value 22 vs 22; P = 0.78). Conclusions. Shorter CAG repeats of the AR gene, presenting high levels of transactivation activity, may play a role in male AS.