Gene linked to transsexualism
In the largest genetic study involving transsexuals to date, researchers in Australia said they found that transexuality may be linked to the androgen receptor (AR) gene – which is known to modify the effect of the male sex hormone testosterone. The finding strengthens the view that there is a biological reason why some people feel they are living in the wrong body, in this case men who have an strong desire to live as a woman.
Vincent Harley, of Prince Henry’s Institute in Melbourne, said his team’s study of Australian and American male-to-female transsexuals found they were more likely to have a genetic variation in a gene that could lead to a feminisation of the brain during early fetal development. The scientists collected DNA samples from 112 male-to-female transsexuals and found that they were more likely to have a longer version of the AR gene than another group of 258 non-transsexual men. The researchers said the longer AR variant gene may have resulted in less effective testosterone signaling, a mechanism that masculinises the brain during early development.
“It is possible that a decrease in testosterone levels in the brain during development might result in incomplete masculinisation of the brain in male-to-female transsexuals, resulting in a more feminised brain and a female gender identity,” the scientists wrote, but added it was highly likely that other genetic factors were also involved in this form of transsexualism.
“There is a social stigma that transsexualism is simply a lifestyle choice, however our findings support a biological basis of how gender identity develops,” said lead researcher Vincent Harley of Monash University’s Prince Henry’s Institute of Medical Research.
The findings are published in the journal Biological Psychiatry.
Other experts, however, argued that the small study population limited the conclusions that could be drawn from the results.
Juliet Richters, an associate professor in sexual health at the University of NSW, said that while the study does not identify the gene as a cause of transsexualism it might provide some comfort for those with the condition.
“It may be a matter of relief for transsexuals to have their condition identified as genetic, rather being blamed for making an awkward lifestyle choice,” she commented, adding that much of the distress felt by transsexuals was caused by cruel treatment from others.
http://news.bbc.co.uk/1/hi/health/7689007.stm
