title: Polymorphic variation in CYP19 and the risk of breast cancer.
abstract: The production of estrogen from androgen via the estrogen biosynthesis pathway is catalyzed by aromatase P450 (cyp19). We have assessed the frequency of allelic variants of the CYP19 intron 4 [TTTA]n repeat in 327 breast cancer cases and 253 controls from southern England. Previous studies have suggested that the [TTTA](10) repeat and [TTTA](12) repeat variants represent low penetrance breast cancer susceptibility alleles. Compared with controls our breast cancer cases had a statistically significant positive association with the [TTTA](10) allele (1.5 versus 0.2%, P = 0.028) and the [TTTA](8) allele (13.5 versus 8.7%, P = 0.012). The frequency of the [TTTA](12) allele was not significantly elevated in our study group compared with controls (2.3 versus 2.2%, P = 1.00). The CYP19 intron 4 [TTTA]n repeat is unlikely to have a functional effect on aromatase activity and it is more likely that the [TTTA](8) and [TTTA](10) variants are in linkage disequilibrium with other functional CYP19 variants.
authors.affiliation: VBCRC Cancer Genetics Laboratory, Peter MacCallum Cancer Institute, Locked Bag No. 1 A'Beckett St., Victoria 8006, Australia.
authors.forename: S W
authors.initials: SW
authors.lastname: Baxter
authors.forename: D Y
authors.initials: DY
authors.lastname: Choong
authors.forename: D M
authors.initials: DM
authors.lastname: Eccles
authors.forename: I G
authors.initials: IG
authors.lastname: Campbell
mesh_terms: D000328:Adult; D017668:Age of Onset; D000368:Aged; D001141:Aromatase / Q000235:genetics*; D001943:Breast Neoplasms / Q000209:etiology / Q000235:genetics*; D004247:DNA / Q000032:analysis; D005260:Female; D005787:Gene Frequency; D014644:Genetic Variation; D005838:Genotype; D006801:Humans; D007438:Introns / Q000235:genetics; D008214:Lymphocytes; D008875:Middle Aged; D011110:Polymorphism, Genetic / Q000235:genetics*; D012307:Risk Factors
chemical_list: D004247:DNA; D001141:Aromatase