Australian and US researchers have discovered that the gene responsible for 'maleness' could explain why men are 50 per cent more likely than women to develop Parkinson's disease (PD). The scientists, based at Prince Henry's Institute in Melbourne and the University of California in Los Angeles, have shown that SRY - the gene that determines gender in the early embryo - is also active in the area of the brain affected by PD. The findings, published in the journal Current Biology, could also help explain why men are at greater risk of some other brain disorders, say the team.
People with PD are affected by tremors, stiff muscles and slow movements, caused by a gradual loss of nerve cells in an area of the brain controlling movement. It is not known what triggers this loss, but PD is not normally inherited. However, the illness does occasionally run in families, where the symptoms often appear at a younger age than in non-inherited cases. The disease is associated with a lack of dopamine, a brain communication chemical.
In the latest study, the team found that the SRY protein is produced in the area of the brain affected by PD, called the substantia nigra, as well as in the embryo. When the scientists lowered the level of SRY in rodent brains, it triggered a drop in dopamine levels, and the animals developed PD-like symptoms.
Team leaders Vincent Harley and Eric Vilain think that variations in genes that influence SRY production, or the SRY gene itself, could contribute to the onset of PD. They suggest that the normal role of SRY in the brain could be to help brain cells produce dopamine, and that men with lower levels of SRY could be at increased risk of developing the disease. 'The SRY gene may also explain the sex differences in other dopamine-linked disorders with a higher incidence in males, such as schizophrenia or addiction', they add.
The team is now comparing SRY levels in brain samples from men who died from Parkinson's disease with those in samples from people who died of other causes. However, although Vilain says he is 'excited' by the discovery, he stressed that any treatments based on the research 'are a long way off'.