HLA-B and breast cancer: The most important differences were found in the HLA-B locus, where the HLA-B7 allele was present with greater frequency in the group of sick patients than in the control group (p = 0.0019; 95% CI, 1.337 – 3.409; Relative risk [RR], 2.135), explaining that in this geographical zone an environmental agent can be found (whether viral or bacterial) that can be associated with breast cancer.