Unusual ovary and testes formation may be triggered by ‘genetic regulator’. 

Australian researchers have discovered a genetic regulator that plays a key role in determining a baby’s sex and, crucially, whether it will become one of the one in every 4500 people with a disorder of sex development.

Led by Andrew Sinclair at the Murdoch Children’s Research Institute (MCRI) in Melbourne, the team isolated a group of so-called “enhancers” that act on a gene that controls the growth of testes in the foetus.

At a basic level, if you’re born with two X chromosomes you become a girl, and if you have an X and a Y chromosome you’re a boy. But whether that genetic blueprint leads to typically male or female gonads, the testes and ovaries, and genitalia, the penis and scrotum, or vulva, vagina and clitoris, depends on a host of other factors.

One of those is the SRY gene, which sits on the Y chromosome and activates another gene called SOX9. It is SOX9 that tells the embryonic gonads, which can go either way, to head down the testes path.

How SRY influences SOX9 has been an enduring mystery, but at least part of the enigma is now in daylight.

The researchers found that three enhancers – sections of DNA that regulate gene expression – are drivers of SOX9, with profound implications when it all goes wrong.

Read the full article in Cosmos magazine here