Gene linked to increased risk of Parkinson's in men

The discovery of a new role for a sex gene could explain why men are one-and-a-half times more likely to develop Parkinson’s disease than women.

Scientists at the University of California at Los Angeles (UCLA), US, found that a sex gene responsible for making embryos male and forming testes is also produced by the brain region targeted by the debilitating neurological disease.

“Our findings may offer new clues to how the disorder affects men and women differently, and shed light on why men are more susceptible to the disease,” says Eric Vilain, a geneticist at UCLA’s David Geffen School of Medicine.

In 1990, UK researchers identified the male gender gene, known as SRY. It is located on the male Y sex chromosome and manufactures a protein that is secreted by cells in the testes.

The UCLA study unexpectedly showed that the SRY protein also appears to help neurons located in an area of the brain known as the substantia nigra – a motor control centre – secrete the neurochemical dopamine.

Brain enzyme

Parkinson’s disease causes these neurons to gradually die, lowering dopamine levels and causing the gradual loss of motor control that is a signature characteristic of the illness, which induces uncontrollable shaking.

“For the first time, we’ve discovered that the brain cells that produce dopamine depend upon a sex-specific gene to function properly,” Vilain says. “We’ve also shown that SRY plays a central role not just in the male genitals, but also in regulating the brain,” he adds.

Researchers used a rat model to study the effect of SRY on the brain and found that when they lowered the protein’s levels, there was also a lowering of an enzyme called tyrosine hydroxylase, which plays a key role in dopamine production. However, this drop in tyrosine hydroxylase occurred in male rodents only, the female rats remained unaffected.

Journal reference: Current Biology