August 22, 2013

Whtever Happened to the “Transsexual Gene”?

In late 2008 there was a media hubbub over a study that supposedly discovered the “transsexualism gene.” I remember reading about it at the time but not really caring too much, as I wasn’t then identifying as trans*, let along thinking of myself as a transwoman. [I had a long period of denial.] Now that I do recognize who I am, I got curious: whatever happened to the “transsexual gene”?

The popular search for a genetic trait that causes deviation from the gender and sexual norm has long been an obsession with media outlets and the public, be it the “Gay Gene,” the “Transsexual Gene,” or whatever. I’m not sure why; perhaps it’s some desire to find something to blame for the perceived abnormality. It’s not my fault I’m transgender! It’s the fault of this gene! At some level, I think the obsession with finding “the gene” lay in the idea that maybe what can be found can be “corrected” or “fixed.” Gene therapy can make me a man again!

Regardless, the question of a bilogical basis for transgender interests me greatly, not because I want to blame or cure, but because I’m fascinated by science and genetics. There’s could also be therapeutic value to treating gender dysphoria in knowing the causes more specifically.

The widely reported 2008 study, Androgen receptor repeat length polymorphism associated with male-to-female transsexualism by Hare, et al, focused on MtF transsexuals and found that in their sample population of 112 MtFs, a particular mutation led to a less effective androgen receptor — i.e., a genetic predisposition against processing testosterone to full efficiency. The speculation is that this could lead to transgender feelings because the brain is, essentially, not so fully male as it would be if the receptors functioned properly. .

As it turns out, further research has not fully borne out the results of that first study.A 2006 study by Elaut, et al, [published prior to Hare, et al] looked at the AR gene as it relates to sexual attraction and concluded that they “could not establish that CAG repeat length is a consistent modulating factor in the relationship between TT or FT and sexual desire in male-to-female transsexuals.” In 2009, Eujike, et al, examined the AR gene along with four other sex hormone-related genes in a group of 74 MtF patients and found “No significant difference in allelic or genotypic distribution of any gene examined was found between MTFs and control males.” Most recently, in January 2013 a study by Lombardo, et al, examined the AR gene along with other sex-determinant genetic markers in a cohort of 30 MtFs. Their conclusions stated that “This gender disorder does not seem to be associated with any molecular mutations of some of the main genes involved in sexual differentiation.” 

The question of a genetic basis for transgender remains an open question. But in terms of the AR gene being the “transgender gene,” the evidence is not convincing. 

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