Is Reduced CAG Repeat Length in Androgen Receptor Gene Associated with Risk of Prostate Cancer in Indian Population?

Shorter CAG repeats in androgen receptor (AR) gene have been found to be associated with an increased risk of prostate cancer (CaP). Ethnic variations in CAG repeat length may contribute to varying risks in different populations. To evaluate the prognostic significance of androgen receptor (AR) CAG repeats in Indian population for CaP, genomic DNA from 113 CaP, 57 benign prostate hyperplasia (BPH) patients and 133 normal healthy controls were examined by using a PCR-based GeneScan analysis. The mean number of CAG repeat in CaP was significantly lower as compared to the healthy controls (20.26 vs 22.98; p = 0.016). The odds ratio for CaP was 2.96 (p < 0.01), when individuals with short CAG repeat (< or =22) were compared with those having longer repeats (>22). A significant association was also observed between short CAG repeat and young age at diagnosis (OR 2.18; p = 0.04). The mean CAG repeat was not significantly different in BPH and healthy controls; however, BPH patients showed a tendency towards short CAG repeats. Thus, our results show that CAG repeat polymorphism in AR gene is significantly associated with CaP risk, suggesting that AR CAG polymorphism may act as a risk modifier to CaP in Indian population.