Rs1056836

rs1056836, also known as 4326C/G, Val432Leu or L432V, is a SNP in the cytochrome P450 1B1 (CYP1B1) gene. This gene is a member of the CYP1 gene family and one of the major enzymes involved in the hydroxylation of estrogens, a reaction likely to be relevant in hormonal carcinogenesis. [In dbSNP orientation, the (C) allele encodes the Leu; the (G) the Val.]

In a study of 153 Hispanic Caucasians with prostate cancer the rs1056836(G;G) genotype showed decreased risk compared to the more common (C;C) genotype (odds ratio = 0.31, p = 0.04, CI: 0.10-0.96).

This report cites another study as indicating that rs1056836(C;C) high-risk stage III and IV breast cancer patients receiving dose-intense paclitaxel in combination with doxorubicin and cyclophosphamide experience a longer progression-free survival compared with patients with (C;G) or (G;G) genotypes.

rs1056836 increases susceptibility to lung cancer among those who never smoked 2.7x times for (C:G) heterozygotes and 3.1x times for (G;G) homozygotes, based on a study of 160 US patients.