BRCA1 and breast cancer: Given the above associations at HMMR and AURKA/CSTF1, the influence of GxG on breast cancer risk in BRCA1/2 mutation carriers was assessed between rs299290 and the genotyped variants in AURKA/TPX2/TUBG1 (n = 22), and between rs2426618 and the genotyped variants in TPX2/TUBG1 (n = 7).