Does gender dysphoria have a genetic basis?
Four genetic variants involved in processing sex hormones are over-represented in transwomen, according to Australian research, indicating there could be a genetic basis for gender dysphoria.
Lead researcher Professor Vincent Harley, from the Hudson Institute of Medical Research in Melbourne, told doctorportal that establishing the role that sex hormones have in gender identity contributes significantly to our understanding of the condition.
“We know that if you look at identical twins and one is trans, there is a 25% chance the other twin will be. That’s not 100%, but the chance is higher than what it is between unrelated people.”
“Therefore, this study might be the first small part of the evidence base, as I think there could be many genes involved, like there is in height or blood pressure.”
Study finds significant association between genes and gender dysphoria
The study, published in the Journal of Clinical Endocrinology & Metabolism, set out to explore the likely genetic component of gender dysphoria. The authors hypothesised that gender dysphoria in transwomen is associated with variants in sex hormone signalling genes responsible for under-masculinisation and/or feminisation.
The research involved 380 transwomen (most of whom were receiving hormone treatment at the time of recruitment) and 344 control males. The authors conducted a DNA analysis, focusing on the functional variants in 12 sex hormone signalling genes and their relationship to gender dysphoria in transwomen.
The results showed a significant association between gender dysphoria and ERα, SRD5A2 and STS alleles, as well as ERα and SULT2A1 genotypes. Several allele combinations were also over-represented in transwomen, most involving AR (AR-ERβ, AR-PGR, AR-COMT, CYP17-SRD5A2).
Existing knowledge about sex hormones informed the research
Professor Harley said the approach the team took was biased and informed by channels of existing literature. One aspect of this was the evidence base on sex hormones.
“We know that when males and females smell sex hormones, different brain regions are activated, and trans women have an atypical response to this”, Professor Harley said.
He said this suggested that the receptors of androgen and oestrogen play some role, and this formed the basis of his investigation.
“I didn’t just take neutral variations of genes. The ones I looked at had already previously been implicated in other conditions like breast cancer, prostate cancer and infertility, so I knew they had functional polymorphism – they are things that do tweak hormone pathways.”
Establishing the role genes play could help reduce discrimination
Professor Harley feels his research is making a difference and improving our understanding of gender dysphoria.
“This work has been helpful to trans people – and I get hundreds of emails from trans people and society at large which suggests that.”
He said that when he started his research 20 years ago, the general public knew little about trans people. “I think gender identity is an important part of the spectrum of human diversity”
“When we establish some biological basis for trans, we can educate the public and this knowledge can help reduce discrimination of the trans community.”
Professor Harley said that as far as clinical implications go, a test will not emerge from the study – nor was this ever the intention of his research on gender dysphoria.
“I’m a biologist, so I was interested in looking at why we feel the sex we do, from a basic biology point of view. This research was more about trying to understand the condition.”