For decades scientists have been trying to find an answer as to what actually determines the sex of a baby. A team of Researchers from the University of Melbourne, Australia conducted a detailed study on the genetic code stored within cells. The research has proved fruitful as the team has found that the activity of the sex-determining genes is directly influenced by a regulator.
The regulator discovered by the scientists helps in determining not just the sex of the baby but also affects the development of the reproductive system after the birth.
The research, published in the Nature Communications journal, has studied the part of DNA which was previously considered ‘junk’ DNA.
Previously it was established that an embryo to develop into a baby girl it must have 2 X chromosomes. For a boy, the combination was one X and one Y chromosome. But the newly discovered working of the gene regulator along with other associated genes can influence the outcome.
The non-coding DNA, previously thought as the ‘junk’ DNA, is part of DNA that does not directly contain information for the synthesis for proteins but scientists have been long working on finding the real purpose of this part.
The non-coding part contains a number of gene regulators that affect gene activity. The working of all the regulators is not well known and is still being investigated. This research has found a link between a regulator and the sex determination.
Brittany Croft from the Murdoch Children’s Research Institute (MCRI) in Australia was the lead author of the research. Croft said, “The Y chromosome carries a critical gene, called SRY, which acts on another gene called SOX9 to start the development of testes in the embryo. High levels of the SOX9 gene are needed for normal testis development. However, if there is some disruption to SOX9 activity and only low levels are present, a testis will not develop resulting in a baby with a disorder of sex development.”
The unusual levels of SOX9 lead to sexual development disorders where the gonads or any related sexual organs are not developed fully. A female can end up having male anatomy on the inside and vice versa. These conditions cause the individual to be termed as intersex, i.e. he/she cannot be categorized under the male or female categories.
This research could help in answering the many questions we have on what causes intersex.
Professor Andrew Sinclair, a member of the Pediatrics Department of the University of Melbourne was also on the research team. Professor Sinclair said, “We discovered three enhancers that, together ensure the SOX9 gene is turned on to a high level in an XY embryo, leading to normal testis and male development,” he said.
“These enhancers lie on the DNA but outside genes, in regions previously referred to as junk DNA or dark matter. The key to diagnosing many disorders may be found in these enhancers which hide in the poorly understood dark matter of our DNA.”
The study was then conducted upon 44 people carrying these intersex traits. The future course of action was focused on linking the enhancers to the genes which they act on.
Mr. Sinclair added, “Importantly, we identified XX patients who would normally have ovaries and be female but carried extra copies of these enhancers, (high levels of SOX9) and instead developed testes. In addition, we found XY patients who had lost these SOX9 enhancers, (low levels of SOX9) and developed ovaries instead of testes.”
This research could provide a better insight into other gene related issues and could prove to be the stepping stone in solving them. “This study is significant because in the past researchers have only looked at genes to diagnose these patients, but we have shown you need to look outside the genes to the enhancers,” says Croft.