BRCA1 and breast cancer: Many BRCA1 polymorphisms with allele frequencies >5% in Caucasians have been identified; however, only six of these (Q356R, D693N, P871L, E1038G, K1183R, and S1613G) result in amino acid changes (BIC-Breast Cancer Information Core; http://research.nhgri.nih.gov/bic/).