CAG and GGN Repeat Length Polymorphisms of Androgen Receptor Gene in Women with Breast Cancer: A Case-Control Study from South India

Aim: The Androgen Receptor (AR) is a ligand-dependent transcriptional activator and the AR gene contains a highly polymorphic trinucleotide repeat CAG and GGN in the first exon. Given the lack of information AR-CAG and GGN repeat polymorphism and its potential correlation with breast cancer in South Indian women, we conducted a case-control study to observe the effects of CAG & GGN repeat length polymorphism and risk of breast cancer. Methods: Polymorphisms for AR-CAG and GGN repeat length was detected by Gene Scan analysis in the genomic DNA from cases with breast cancer and controls. Results: Association between AR genotype was calculated by categorising alleles as short (S) and long (L) and taking median value as the cut-off. LL genotype of CAG repeat was found to be associated with breast cancer (OR, 4.58; 95% CI, 10.61 1.98; p—0.0004). GGN repeat having ≥21 was found in most of the cases and none of the cases showed 20 repeats thus indicate that alleles having homozygous repeat 20 may be protective towards breast cancer. Also, SS genotype was observed in 56.84% of cases and in 73.03% of controls (OR, 0.48; 95% CI, 0.26 0.89; p value, 0.02). Conclusion: Our results indicate that longer CAG and GGN repeat may be associated with breast cancer whereas, the shorter GGN repeat length genotype of AR are protective.