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Gene Linked to Transsexuals

Posted on: Monday, 27 October 2008, 08:20 CDT

Could a gene linked with testosterone impact the occurrence of male transsexuals? Australian scientists say yes, according to new research.

Research Vincent Harley said, “There is a social stigma that transsexualism is simply a lifestyle choice, however our findings support a biological basis of how gender identity develops.”

DNA analysis from 112 male-to-female transsexual volunteers showed they were more likely to have a longer version of the androgen receptor gene; a genetic difference that may cause weaker testosterone signals.

The team reported the findings in the journal Biological Psychiatry.

Researchers looked for potential differences in three genes known to be involved in sex development: coding for the androgen receptor, the estrogen receptor and an enzyme that converts testosterone to estrogen.

They compared DNA from the male to female transsexual participants with 258 controls that showed a significant link with a long version of the androgen receptor gene and transsexualism.

Increasingly, biological factors are being implicated in gender identity.

One study has revealed certain brain structures in male-to-female transsexual people are more "female like".

Terry Reed from the Gender Identity Research and Education Society said she was convinced of a biological basis to transsexualism.

"This study appears to reinforce earlier studies which have indicated that, in some trans people, there may be a genetic trigger to the development of an atypical gender identity.

"However, it may be just one of several routes and, although it seems extremely likely that a biological element will always be present in the aetiology of transsexualism, it's unlikely that developmental pathways will be the same in all individuals."

Researchers say longer versions of the androgen receptor gene are associated with less efficient testosterone signaling.

Reduced action of the male sex hormone may impact gender development in the womb, the researchers speculated.

"We think that these genetic differences might reduce testosterone action and under masculinize the brain during fetal development," said researcher Lauren Hare from Prince Henry's Institute of Medical Research.

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On The Net:

Biological Psychiatry

Gender Identity Research and Education Society

Source: redOrbit staff

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