title: Association study of ERβ, AR, and CYP19A1 genes and MtF transsexualism.
abstract: BACKGROUND
  The etiology of male-to-female (MtF) transsexualism is unknown. Both genetic and neurological factors may play an important role.
  
  
  OBJECTIVE
  To investigate the possible influence of the genetic factor on the etiology of MtF transsexualism.
  
  
  METHODS
  We carried out a cytogenetic and molecular analysis in 442 MtFs and 473 healthy, age- and geographical origin-matched XY control males. The karyotype was investigated by G-banding and by high-density array in the transsexual group. The molecular analysis involved three tandem variable regions of genes estrogen receptor β (ERβ) (CA tandem repeats in intron 5), androgen receptor (AR) (CAG tandem repeats in exon 1), and CYP19A1 (TTTA tandem repeats in intron 4). The allele and genotype frequencies, after division into short and long alleles, were obtained.
  
  
  METHODS
  We investigated the association between genotype and transsexualism by performing a molecular analysis of three variable regions of genes ERβ, AR, and CYP19A1 in 915 individuals (442 MtFs and 473 control males).
  
  
  RESULTS
  Most MtFs showed an unremarkable 46,XY karyotype (97.96%). No specific chromosome aberration was associated with MtF transsexualism, and prevalence of aneuploidy (2.04%) was slightly higher than in the general population. Molecular analyses showed no significant difference in allelic or genotypic distribution of the genes examined between MtFs and controls. Moreover, molecular findings presented no evidence of an association between the sex hormone-related genes (ERβ, AR, and CYP19A1) and MtF transsexualism.
  
  
  CONCLUSIONS
  The study suggests that the analysis of karyotype provides limited information in these subjects. Variable regions analyzed from ERβ, AR, and CYP19A1 are not associated with MtF transsexualism. Nevertheless, this does not exclude other polymorphic regions not analyzed.
authors.affiliation: Departamento de Psicobiología, Universidad de A Coruña, A Coruña, Spain.
authors.forename: Rosa
authors.initials: R
authors.lastname: Fernández
authors.forename: Isabel
authors.initials: I
authors.lastname: Esteva
authors.forename: Esther
authors.initials: E
authors.lastname: Gómez-Gil
authors.forename: Teresa
authors.initials: T
authors.lastname: Rumbo
authors.forename: Mari Cruz
authors.initials: MC
authors.lastname: Almaraz
authors.forename: Ester
authors.initials: E
authors.lastname: Roda
authors.forename: Juan-Jesús
authors.initials: JJ
authors.lastname: Haro-Mora
authors.forename: Antonio
authors.initials: A
authors.lastname: Guillamón
authors.forename: Eduardo
authors.initials: E
authors.lastname: Pásaro
mesh_terms: D000328:Adult; D000483:Alleles; D001141:Aromatase / Q000235:genetics* / Q000502:physiology; D016022:Case-Control Studies; D002869:Chromosome Aberrations; D047629:Estrogen Receptor beta / Q000235:genetics*; D005260:Female; D005838:Genotype; D012739:Gonadal Steroid Hormones / Q000235:genetics; D006801:Humans; D007621:Karyotyping; D008297:Male; D011944:Receptors, Androgen / Q000235:genetics*; D020080:Tandem Repeat Sequences / Q000235:genetics; D014189:Transsexualism / Q000235:genetics*
chemical_list: C410798:AR protein, human; D047629:Estrogen Receptor beta; D012739:Gonadal Steroid Hormones; D011944:Receptors, Androgen; D001141:Aromatase; C561410:CYP19A1 protein, human
keywords: Androgen Receptor; Aromatase; Estrogen Receptor; Gender Dysphoria; Male-to-Female Transsexuals; Transsexualism