The SRY or the sex determination gene, that plays a crucial role in deciding if an embryo should develop into a male or female (embryo with SRY gene develops into a male), could explain the high incidence of Parkinson's disease in men. The SRY protein, required for formation of testes is also produced by Parkinson's affected areas in the brain, report researchers from Prince Henry's Institute and University of California.
The SRY gene was discovered in 1990 and is present only in the male. The gene is transmitted from father to son and is not present in females. It could contribute to different aspects related to control of physical movement and brain function, according to Vincent Harley, one of the senior researchers. Clearly, more research is needed to better understand the role of SRY gene in co-ordination of body movements.
Parkinson's disease is a chronic disease characterized movement disorder and affects nearly 40,000 Australians. It is 1.5 times more likely to occur in men compared to women. The disease is associated with an earlier age of onset in one out of seven Parkinson's sufferers and is highly variable in terms of symptoms and disease progression. There is no proper available cure or treatment for this disease. Surgery and medication may be of limited help.
A region of the brain called substantia nigra, has been found to secrete small amount of the SRY protein. It is this region of the brain that deteriorates in Parkinson's disease patients.
With death of cells in the substantia nigra, there is less production of dopamine that signals the brain regarding co-ordination and movement of the body parts. As a consequence, patients lose their ability to initiate or have control over their body movements and eventually end up with paralysis.
The research team analyzed the effects of low SRY protein levels in animals designed to mimic human models of Parkinson's disease. Parkinson's-like movement problems in animals were manifested in animals with low SRY level in the substantia nigra of animal brain.
'We were surprised to find a function for SRY outside the testes. 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,' remarked the researchers.
Following this finding, the researchers hypothesize that men with low SRY levels could face an increased risk of developing Parkinson's disease. Furthermore, genetic variations in the SRY gene could confer an increased or decreased susceptibility to the disease. With improved understanding of such genetic mechanisms, it might be possible to identify at-risk individuals at an early stage.