title: CYP gene polymorphisms and early menarche.
abstract: Early age at menarche is a risk factor for breast cancer. A previous study reported a significant positive association between the CYP3A4*1B variant allele and early puberty. We investigated whether polymorphisms of the CYP3A4, CYP17, CYP1B1, and CYP1A2 genes predict the age at onset of menarche. Five hundred eighty-three nulliparous women between ages 17 and 35, of various ethnic backgrounds, completed a questionnaire that included information about menstrual history. Samples of DNA were provided and used to genotype these women for polymorphic variants in the four genes. There was no significant difference in mean age at menarche between women who carried two variant CYP17 A2 alleles (12.5 years) and women who carried one or no variant allele (12.5 years) (P = 0.8, adjusted for ethnic group and year of birth). Similar results were found for the CYP1B1*3 variant allele and for the CYP1A2*1F variant allele. Women who carried two variant CYP3A4*1B alleles had an earlier mean age at menarche (12.0 years) than women who carried one or no variant allele (12.6 years) (P = 0.02). However, after adjusting for ethnic group and year of birth, no significant differences in mean age at menarche were found. The polymorphic variants of the CYP3A4, CYP17, CYP1B1, and CYP1A2 genes are unlikely to influence age of menarche.
authors.affiliation: Centre for Research in Women's Health, University of Toronto, 790 Bay Street, Toronto, Ontario, M5G 1N8, Canada.
authors.forename: J
authors.initials: J
authors.lastname: Lai
authors.forename: D
authors.initials: D
authors.lastname: Vesprini
authors.forename: W
authors.initials: W
authors.lastname: Chu
authors.forename: H
authors.initials: H
authors.lastname: Jernström
authors.forename: S A
authors.initials: SA
authors.lastname: Narod
mesh_terms: D000293:Adolescent; D000328:Adult; D019388:Cytochrome P-450 CYP1A2 / Q000235:genetics*; D051544:Cytochrome P-450 CYP3A; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics*; D005260:Female; D006801:Humans; D016014:Linear Models; D008572:Menarche / Q000235:genetics*; D006899:Mixed Function Oxygenases / Q000235:genetics*; D011110:Polymorphism, Genetic; D013254:Steroid 17-alpha-Hydroxylase / Q000235:genetics*
chemical_list: D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; C104464:CYP3A protein, human; D019388:Cytochrome P-450 CYP1A2; D051544:Cytochrome P-450 CYP3A; D013254:Steroid 17-alpha-Hydroxylase; C510163:CYP3A4 protein, human