Combined profile of the tandem repeats CAG, TA and CA of the androgen and estrogen receptor genes in breast cancer

Purpose Case–control studies have reported inconsistent results concerning the association between polymorphisms in the androgen and estrogen receptor (ER) genes and breast cancer. While several studies investigated the association between the androgen receptor (AR) gene, CAG repeat and breast cancer, for the CA and TA repeats in the ER genes there are considerably fewer studies (one for CA and none for TA). Methods We have investigated the potential link between three tandem repeats (CAG, TA, and CA) in the AR, ERs α and β genes, respectively, and breast cancer. DNA was isolated from 153 invasive breast tumors and 318 controls, and the three tandem repeats were sized by polyacrylamide electrophoresis. Number of repeats in each allele and the total repeats of both alleles were taken as variables for classification into dichotomous groups using the median of each variable in the control group as cut-off point. Relationship between polymorphic tandem repeats and breast cancer was assessed by multivariate logistic regression models. Results Three variables combined, longer CAGsum (≥28), shorter TA (<23) and CA (<23) repeats could constitute a possible genetic profile associated with breast cancer. Conclusions Our results confirm previous reports regarding an association between longer CAG repeats and breast cancer. In addition to that, we found that the combination of long CAG, short TA and CA repeats are strongly associated with breast cancer.