Evidence of biological basis for MTF transgender / transsexualism

[janetanne]

(MTF) Transsexual gene link found

Australian researchers have identified a significant link between a gene involved in testosterone action and male-to-female transsexualism.

DNA analysis from 112 male-to-female transsexual volunteers showed they were more likely to have a longer version of the androgen receptor gene.

The genetic difference may cause weaker testosterone signals, the team reported in Biological Psychiatry.

However, other genes are also likely to play a part, they stressed.

Increasingly, biological factors are being implicated in gender identity. [...]

Apparently, we MTF's really are a third gender, of sorts.

Transsexual gene link identified

Australian researchers have identified a significant link between a gene involved in testosterone action and male-to-female transsexualism.

DNA analysis from 112 male-to-female transsexual volunteers showed they were more likely to have a longer version of the androgen receptor gene.

The genetic difference may cause weaker testosterone signals, the team reported in Biological Psychiatry.

However, other genes are also likely to play a part, they stressed.

Increasingly, biological factors are being implicated in gender identity.

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

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

In the latest study, researchers looked for potential differences in three genes known to be involved in sex development - coding for the androgen receptor, the oestrogen receptor and an enzyme which converts testosterone to oestrogen.

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

Testosterone

It is known that longer versions of the androgen receptor gene are associated with less efficient testosterone signalling.

This reduced action of the male sex hormone may have an effect on gender development in the womb, the researchers speculated.

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

Co-author Professor Vincent Harley added: "There is a social stigma that transsexualism is simply a lifestyle choice, however our findings support a biological basis of how gender identity develops."

Although this is the largest genetic study of transsexualism to date, the researchers now plan to see if the results can be replicated in a larger population.

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."

Story from BBC NEWS:
http://news.bbc.co.uk/go/pr/fr/-/2/hi/health/7689007.stm

Published: 2008/10/26 13:01:09 GMT

© BBC MMIX

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Comments

[auntysarah]

"Male Transsexual"?

[gg_the_undead]

getting past issues such as the small sample size, whether there are other genes that interact with this one, environmental factors, and the whole correlation != causation thing, i worry when i see studies like this.

will this lead to prenatal screening for "the transsexualism gene"? aborting fetuses who are positive for the gene, cos of course it's the most horrid thing in the world to have a trans child? forced genetic "therapy" to remove the effects of this gene? gatekeeping becoming even more rigid, with a positive "trans gene" test being required to receive treatment?

there are some things better left unanswered. trying to find a "cause" of a normal variation that is harmless to both the individual involved and society and yet is demonized by said society, is going down a very dangerous path.

i've already seen statements from xtian extremists that should a "gay gene" be found with certainty, that they would be willing to permit aborting a fetus shown to have said gene. in other words, this research can be enabling eugenics.

[lisaquestions]

This study is problematic because taking the numbers to their fullest extent, more cis men have this gene than trans women.

I also question the point of the comment "Apparently, we MTF's really are a third gender, of sorts." No, we're not. Even being able to point to a biological basis for being transsexual doesn't suddenly make trans women's gender different from cis women's gender.

[baglieg]

Yeah, if you look at the actual numbers, this study is kind of ludicrous. About half the cis people had the gene, but almost half the trans women didn't have the gene. Since cis people outnumber trans people by quite a bit, that means that more than 99% of people who have the gene are not trans. Maybe more than 99.9%.

Also worth noting is that "significant" in statistics doesn't mean in science what it means in plain English. In this case, it means that, given the sample size, there's just barely enough of a correlation for them to believe that there is any link at all, no matter how weak; if they'd had one less trans woman with the gene then the correlation would have been indistinguishable from random experimental noise.