Polymorphic variation in CYP19 and the risk of breast cancer

The production of estrogen from androgen via the estrogen biosynthesis path way 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 ca ncer cases and 253 controls from southern England. Previous studies have su ggested that the [TTTA](10) repeat and [TTTA](12) repeat variants represent low penetrance breast cancer susceptibility alleles, Compared with control s our breast cancer cases had a statistically significant positive associat ion 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) al lele was not significantly elevated in our study group compared with contro ls (2.3 versus 2.2%, P = 1.00), The CYP19 intron 4 [TTTA](n) repeat is unli kely to have a functional effect on aromatase activity and it is more likel y that the [TTTA](8) and [TTTA](10) variants are in linkage disequilibrium with other functional CYP19 variants.