The CYP17 MspA1 Polymorphism and the Gender Dysphoria.
BACKGROUND
The A2 allele of the CYP17 MspA1 polymorphism has been linked to higher levels of serum testosterone, progesterone, and estradiol.


OBJECTIVE
To determine whether the CYP17 MspA1 polymorphism is associated with transsexualism.


METHODS
We analyzed 151 male-to-female (MtF), 142 female-to-male (FtM), 167 control male, and 168 control female individuals. Fragments that included the mutation were amplified by PCR and digested with MspA1. Our data were compared with the allele/genotype frequencies provided by the 1000 Genomes Data Base, and contrasted with a MEDLINE search of the CYP17 MspA1 polymorphism in the literature.


METHODS
We investigated the association between transsexualism and the CYP17 MspA1 polymorphism.


RESULTS
A2 frequency was higher in the FtM (0.45) than the female control (0.38) and male control (0.39) groups, or the MtF group (0.36). This FtM > MtF pattern reached statistical significance (P = 0.041), although allele frequencies were not gender specific in the general population (P = 0.887). This observation concurred with the 1000 Genomes Data Base and the MEDLINE search.


CONCLUSIONS
Our data confirm a sex-dependent allele distribution of the CYP17 MspA1 polymorphism in the transsexual population, FtM > MtF, suggestive of a hypothetical A2 involvement in transsexualism since the allele frequencies in the general population seem to be clearly related to geographic origin and ethnic background, but not sex.
Departamento de Psicología, Área Psicobiología, Universidade da Coruña, A Coruña, Spain.
Rosa
R
Fernández
Departamento de Psicología, Área Psicobiología, Universidade da Coruña, A Coruña, Spain.
Joselyn
J
Cortés-Cortés
Unidad de Transexualidad e Identidad de Género, Hospital Carlos Haya, Málaga, Spain.
Isabel
I
Esteva
Unidad de Identidad de Género, Hospital Clinic, Barcelona, Spain.
Esther
E
Gómez-Gil
Unidad de Transexualidad e Identidad de Género, Hospital Carlos Haya, Málaga, Spain.
Mari Cruz
MC
Almaraz
Departamento de Psicología, Área Psicobiología, Universidade da Coruña, A Coruña, Spain.
Estefanía
E
Lema
Departamento de Psicología, Área Psicobiología, Universidade da Coruña, A Coruña, Spain.
Teresa
T
Rumbo
Unidad de Transexualidad e Identidad de Género, Hospital Carlos Haya, Málaga, Spain.
Juan-Jesús
http://orcid.org/0000-0002-6679-7812
JJ
Haro-Mora
Unidad de Identidad de Género, Hospital Clinic, Barcelona, Spain.
Ester
E
Roda
Departamento de Psicobiología, UNED, Madrid, Spain.
Antonio
A
Guillamón
Departamento de Psicología, Área Psicobiología, Universidade da Coruña, A Coruña, Spain.
Eduardo
E
Pásaro
D000483:Alleles; D005260:Female; D005787:Gene Frequency; D005838:Genotype; D006630:Hispanic or Latino / Q000523:psychology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic / Q000235:genetics*; D013254:Steroid 17-alpha-Hydroxylase / Q000235:genetics*; D014189:Transsexualism / Q000235:genetics* / Q000523:psychology
D013254:Steroid 17-alpha-Hydroxylase
CYP17A1 Gene; CYP17 MspA1 Polymorphism; Female-to-Male; Gender Dysphoria; Male-to-Female; Transsexualism; rs743572