CYP19A1 and breast cancer: Two of the polymorphisms, the tetra-nucleotide repeat ([TTTA]n) polymorphism which varies from 7 to 13 repeats in intron 4 and a C → T single nucleotide polymorphism (SNP) (rs10046) in the 3′-UTR of the CYP19 gene, have been frequently studied for BC associations with inconsistent results.