Correlation of major histocompatibility complex class I related A (MICA) polymorphism with the risk of developing breast cancer.

In the present study, we examined the association of different alleles of MICA gene with the risk of breast cancer development in Iranian population. Our data showed a significant relationship between longer alleles, alleles with 9- and 6-GCT repeat of MICA gene, and a higher risk of developing breast cancer according to the age of onset. The data indicated a 6-fold increase for developing breast cancer in patients carrying the allele with 6-GCT repeat after age 50 (OR = 5.8333, 95% CI: 1.2976-26/2236, P = 0.0172). In addition, patients carrying longer alleles in their genotype (6/6, 6/9, and 9/9 genotypes) were found significantly at higher risk of developing breast cancer than control individuals (OR = 5.6, P = 0.0038, 95% CI: 1.6578-18.9166). In contrast, alleles with short GCT repeat of 4 and 5.1 showed to play a role in reducing the risk of breast cancer (OR = 0.79, P = 0.3643 and 95% CI: 0.4743-1.3157). Women with allele 4 were found twofold more protected against breast cancer (OR = 0.4597, 95% CI: 0.2164-0.9765, P = 0.0401). The results suggested that women with genotypes with 9- and 6-GCT repeat alleles of MICA gene could be considered more potent to develop breast cancer especially at higher age.