title: Androgen receptor repeat length polymorphism associated with male-to-female transsexualism.
abstract: BACKGROUND
  There is a likely genetic component to transsexualism, and genes involved in sex steroidogenesis are good candidates. We explored the specific hypothesis that male-to-female transsexualism is associated with gene variants responsible for undermasculinization and/or feminization. Specifically, we assessed the role of disease-associated repeat length polymorphisms in the androgen receptor (AR), estrogen receptor beta (ERbeta), and aromatase (CYP19) genes.
  
  
  METHODS
  Subject-control analysis included 112 male-to-female transsexuals and 258 non-transsexual males. Associations and interactions were investigated between CAG repeat length in the AR gene, CA repeat length in the ERbeta gene, and TTTA repeat length in the CYP19 gene and male-to-female transsexualism.
  
  
  RESULTS
  A significant association was identified between transsexualism and the AR allele, with transsexuals having longer AR repeat lengths than non-transsexual male control subjects (p=.04). No associations for transsexualism were evident in repeat lengths for CYP19 or ERbeta genes. Individuals were then classified as short or long for each gene polymorphism on the basis of control median polymorphism lengths in order to further elucidate possible combined effects. No interaction associations between the three genes and transsexualism were identified.
  
  
  CONCLUSIONS
  This study provides evidence that male gender identity might be partly mediated through the androgen receptor.
authors.affiliation: Human Molecular Genetics Laboratory, Prince Henry's Institute of Medical Research, Melbourne, Australia.
authors.forename: Lauren
authors.initials: L
authors.lastname: Hare
authors.forename: Pascal
authors.initials: P
authors.lastname: Bernard
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Sánchez
authors.forename: Paul N
authors.initials: PN
authors.lastname: Baird
authors.forename: Eric
authors.initials: E
authors.lastname: Vilain
authors.forename: Trudy
authors.initials: T
authors.lastname: Kennedy
authors.forename: Vincent R
authors.initials: VR
authors.lastname: Harley
mesh_terms: D000483:Alleles; D001141:Aromatase / Q000235:genetics; D047629:Estrogen Receptor beta / Q000235:genetics; D005260:Female; D005783:Gender Identity; D020022:Genetic Predisposition to Disease; D006801:Humans; D008297:Male; D011110:Polymorphism, Genetic; D011944:Receptors, Androgen / Q000235:genetics* / Q000502:physiology; D012091:Repetitive Sequences, Nucleic Acid; D014189:Transsexualism / Q000235:genetics*
chemical_list: D047629:Estrogen Receptor beta; D011944:Receptors, Androgen; D001141:Aromatase