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Genetics of gender identity
Summary
Gender identity is the gender with which a person identifies. Studies suggest that gender identity is affected by genetic, prenatal hormonal or postnatal social determinants. We are investigating the role of genes in patients with gender identity disorders. Currently we are undertaking genetic association studies of steroidogenesis genes in a large cohort of male-to-female transsexuals.
Description
From a very early age people develop an inner sense of being male or female. However some individuals develop a strong cross-gender identity and report clinically significant distress because they feel that their anatomic traits do not reflect their true gender identity - a situation defined as transsexualism. Little is known about the aetiology of transsexualism.
Several case reports on co-occurrence of transsexualism in families raised the question of whether gender identity is heritable. Genetic studies of girls with congenital adrenal hyperplasia, and polycystic ovarian syndrome point to excess androgen activity as related to the higher incidence of male gender role behaviour.
We have recently demonstrated a significant association between variable polymorphism lengths in the androgen receptor gene and male-to-female transsexualism when compared to non-transsexual male controls. This project will investigate if other sex steroidogenesis genes are associated with transsexualism in a larger cohort (n=200).
A molecular understanding of gender identity will also aid in sex reassignment decisions in children born with disorders of sex development, such as ambiguous genitalia.
Funding
National Health and Medical Research Council
Outcomes
Established the world's largest DNA bank of male-to-female transsexuals.
Identified a genetic association between the certain polymorphisms in the androgen receptor gene and male-to-female transsexualism.
Selected Publications
Hare, L., Bernard, P., Sánchez, F.J., Baird, P.N., Vilain, E., Kennedy, T. and Harley, V.R. (2009) Androgen receptor repeat length polymorphism associated with male-to-female transsexualism. Biological Psychiatry, 65: 93-96.
New Scientist (2008). Emma Young. Male-to-female transsexualism gene found. Oct 27. (commentary)
Holden, C. (2008). Gender and the Brain. Science 322: 831 November 7. (commentary)