To date, genome-wide association studies (GWAS) [3–7] have identified MD-associated single-nucleotide polymorphisms (SNPs) at 13 loci (1q12.21, AREG, PRDM6, TAB2, CCDC170/ESR1, ESR1, 8p11.23, ZNF365, LSP1, IGF1, 12q24, TMEM184B, and SGSM3/MKL1) across the genome, most of which have also been associated with breast cancer. The gene discussed is ESR1; the disease is breast cancer.