Long-term exposure to oestrogens is a well-recognised risk factor for breast cancer, whereas little is known about the influence of polymorphisms of genes involved in oestrogen biosynthesis and metabolism.
A candidate, containing a single bp polymorphism, T-C, (designated, A2 allele), might be the CYPI 7 gene, which codes for an enzyme involved in oestrogen synthesis.
This polymorphism creates an additional Sp1-type promoter site (CCACC box), which has been shown to be associated with increased serum oestrogen levels.
We performed a case-control study, to evaluate association of the CYP17 gene polymorphism with risk of breast cancer in young women (younger than 37 years).
We found a statistically significant increased risk in carriers of at least I A2 allele [odds ratio (OR), 2.0 ; 95% confidence interval (Cl), 1.1-3.5, p=0.027], and a trend toward a gene-dose effect illustrated by a slightly higher risk for A2-homozygous subjects (OR, 2.8) than for heterozygous women (OR, 1.9).
Furthermore, when we investigated the CYP17 genotype in relation to tumour characteristics, breast cancer patients with I or 2 A2 alleles tended to have lower oestrogen receptor levels (risk ratio, 0.70 ; Cl, 0.41-1.2, p=0.44).
Our findings suggest that CYPI 7 gene polymorphism influences breast carcinogenesis in young women.
Mots-clés Pascal : Tumeur maligne, Glande mammaire, Facteur risque, Polymorphisme, Epidémiologie, Gène, Variabilité génétique, Steroid 17alpha-monooxygenase, Oxidoreductases, Enzyme, Etude cas témoin, Suède, Europe, Femelle, Adulte jeune, Homme, Glande mammaire pathologie, Génétique
Mots-clés Pascal anglais : Malignant tumor, Mammary gland, Risk factor, Polymorphism, Epidemiology, Gene, Genetic variability, Steroid 17alpha-monooxygenase, Oxidoreductases, Enzyme, Case control study, Sweden, Europe, Female, Young adult, Human, Mammary gland diseases, Genetics
Notice produite par :
Inist-CNRS - Institut de l'Information Scientifique et Technique
Cote : 99-0385325
Code Inist : 002B20E02. Création : 22/03/2000.