SMAD4 and breast cancer: The present study evaluates the association between 13 SNPs located in driver genes MAP3K1, SF3B1, SMAD4, ARID2, ATR, KMT2C, MAP3K13, NCOR1, and TBX3 with familial and early-onset sporadic BC, studying cases and controls from Chilean families negative for BRCA1/2 point mutations.