Written in DNA – study reveals potential biological basis for transgender

A new study has uncovered a link between being transgender and changes in genes that process the sex hormones estrogen and androgen, revealing a possible biological basis for gender dysphoria.

Professor Vincent Harley

Scientists at Hudson Institute of Medical Research, Melbourne analysed DNA from 380 transgender women (male-to-female transgender people) and found that certain ‘versions’ of 12 different genes were significantly overrepresented in transgender women, compared to non-transgender males.

“This is the world’s largest and most comprehensive study examining changes in genes that control sex hormone signalling in transgender women. It identifies several new genes or genetic variations never before looked at in gender dysphoria,” lead author, Professor Vincent Harley of Hudson Institute, said.

Prof Harley led the study with Honours student, Madeleine Foreman in collaboration with the Monash Gender Clinic, University of Missouri (USA) and the Children’s National Health System (USA). The findings have just been published in The Journal of Clinical Endocrinology & Metabolism.

What is gender dysphoria?

  • Gender dysphoria is the distress felt by people whose sense of being male or female differs from the gender they are assigned at birth based on their sex.
  • For some people, the difference between their gender identity and physical characteristics can cause significant and persistent emotional distress. The terms ‘transgender’ or ‘gender diverse’ are often used to describe these identities.
  • Estimates of the prevalence of gender dysphoria are increasing and range from 0.1 to 1 per cent of the population.
  • People with gender dysphoria have increased rates of depression, anxiety, eating disorders, self-harm and suicide.
  • Not all people who identify as transgender or who experience gender dysphoria take steps to transition socially or physically from their birth sex to their experienced gender.

The team looked specifically at transgender women, or people assigned male at birth who later take steps to affirm their gender identity as female through cross-hormone treatment and surgery.

They identified variations in a handful of genes which are involved in a pathway that processes estrogen and androgen (including testosterone), the male and female sex hormones.

“We propose these genetic variations could make some males less able to process androgen, causing the brain to develop differently – with areas that are less ‘masculine’ or more ‘feminine’ – which may contribute to gender dysphoria in transgender women,” Prof Harley explained.

“While it should not hinge on science to validate people’s individuality and lived experience, these findings may help to reduce discrimination, lend evidence towards improving diagnosis or treatment, promote greater awareness and acceptance and reduce the distress experienced by transgender people in our communities,” Prof Harley said.

“What makes you feel like a male or female is complex and involves interactions between many different genes, much like height, weight or blood pressure. However, while genes play a role, they are not the only factors involved in determining gender identity,” he said.

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