| Updated at: 1543 PST, Wednesday, February 02, 2011|
PARIS: An international consortium of scientists has found five variants of genes which are linked to Parkinson's disease, bringing the tally to 11, according to a paper published on Wednesday by The Lancet.
Until the first genetic clue was found in 1997, the medical consensus was that Parkinson's had environmental -- in other words, non-inherited -- causes.
The five variants were netted in an overview of genomic studies carried out by scientists in Britain, Germany, France, Iceland, the Netherlands and the United States.
None of the tiny DNA changes is responsible by itself for causing for this complex disease of the nervous system, but in conjunction with other variants, boosts the risk of it.
The 20 percent of patients who had the highest number of variants were two and a half times likelier to develop Parkinson's compared to the 20 percent with the least variants, the researchers found.
Parkinson's is a motor-system disorder which primarily affects people over the age of 50 and can lead to such severe trembling, stiffness and loss of balance that patients have trouble walking, talking or performing basic tasks.
The disease has been traced to the loss of cells which produce dopamine, a neurotransmitter that ferries chemical messages within the brain.
There is no known cure, although the condition can be alleviated by a dopamine substitute.
That means the new findings are of limited use for clinicians, but they do add powerfully to the store of fundamental knowledge about the disease, the commonest neuro-degenerative disorder after Alzheimer's, the investigators said.