title: Association of polymorphisms of the oestrogen receptor alpha gene with the age of menarche.
abstract: BACKGROUND
  The age of menarche may be subject to hereditary influences, but the specific genetic determinants are largely unknown. We evaluated whether the XbaI and PvuII polymorphisms of the estrogen receptor alpha gene are associated with the age of menarche.
  
  
  METHODS
  We performed genotyping for XbaI and PvuII in a cohort of 145 adolescent females from a closed community in North-Western Greece.
  
  
  RESULTS
  There was strong linkage disequilibrium between the two polymorphisms. Menarche occurred later in girls with the XX genotype than in girls with the Xx or xx genotype (mean +/- SD: 13.36 +/- 1.24 versus 12.80 +/- 1.14 and 12.75 +/- 1.35 years respectively; P = 0.017). Menarche also tended to occur later in PP homozygotes than in Pp and pp subjects, but the difference was not significant (mean +/- SD: 13.09 +/- 1.29 versus 12.80 +/- 1.19 and 12.85 +/- 1.33 years respectively). The strongest effect was seen when the PX haplotype was considered [mean +/- SD: 13.43 +/- 1.18 years for homozygotes versus 12.76 +/- 1.25 years in heterozygotes and in subjects without the PX allele, P = 0.006].
  
  
  CONCLUSIONS
  We document that the XbaI polymorphism, and possibly PvuII, may be genetic determinants of the age of menarche.
authors.affiliation: Division of Endocrinology, Department of Internal Medicine, University of Ioannina School of Medicine, Ioannina 45110, Greece.
authors.forename: I
authors.initials: I
authors.lastname: Stavrou
authors.forename: C
authors.initials: C
authors.lastname: Zois
authors.forename: J P A
authors.initials: JP
authors.lastname: Ioannidis
authors.forename: A
authors.initials: A
authors.lastname: Tsatsoulis
mesh_terms: D000293:Adolescent; D000375:Aging / Q000502:physiology*; D000483:Alleles; D002648:Child; D015331:Cohort Studies; D047628:Estrogen Receptor alpha; D005260:Female; D005838:Genotype; D006239:Haplotypes; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D015810:Linkage Disequilibrium; D008572:Menarche / Q000502:physiology*; D011110:Polymorphism, Genetic / Q000502:physiology*; D011960:Receptors, Estrogen / Q000235:genetics*
chemical_list: D047628:Estrogen Receptor alpha; D011960:Receptors, Estrogen