Increased risk of breast cancer in women bearing a combination of large CAG and GGN repeats in the exon 1 of the androgen receptor gene

The allelic distribution of CAG and GGN polymorphisms was similar in cases and controls. The mean of short and long CAG and GGN alleles did not show differences between cases and controls and the same was true when the average length of both CAG alleles (CAGn) and GGN alleles (GGNn) was considered. However, when CAGn and GGNn were categorised using 22 and 24 repeats as the cut-off point, respectively, significant differences between cases and controls were observed. The CAGn > 22 repeats were more frequent in cases than in controls, being associated with an increased risk of BC (OR = 1.49; CI95% = 1.06-2.09; p = 0.021). No significant differences were found for categorised GGNn. For CAGn/GGNn combinations, the highest BC risk was found to be associated with the CAGn > 22/GGNn ⩾ 24 combination (OR = 2.47; CI95% = 1.37-4.46; p = 0.003). In conclusion, our results indicate that longer CAGn/GGNn combinations increase the risk of BC and suggest that CAG and GGN AR polymorphisms should be considered in order to assess the BC risk.