DNMT3A and breast cancer: Previous literatures elicited that DNMT3A polymorphisms were mainly associated with susceptibility of solid tumors, such as gastric carcinoma [28–31], colorectal cancer [32], hepatocellular carcinoma [33], ovarian cancer [34, 35] and breast cancer [36, 37] Besides, DNMT3A polymorphisms can lead to changes in methylation of downstream genes, such as LINE-1 and the imprinted gene PEG3 [38–40].