A team at Imperial College London and Liege University in Belgium discovered that 570 out of the 25,000 human genes were acting abnormally. Further research will now be carried out in the hope of finding new treatments.

Scientists believe that by manipulating the way the genes act "we may be able to control or even stop" Parkinson's from developing further after diagnosis.

The Parkinson's Disease Society, which funded the research, said the cause of the condition was unknown and it would continue to pay for such work in the hope of finding the answer.

The boxer Muhammad Ali, the actor Michael J Fox and former Arsenal and Liverpool footballer Ray Kennedy are among famous sufferers, and there are some 120,000 people with the condition in the UK and more than a million in the US.

Dawn Duke, from Imperial College, said the knowledge of which genes were involved would open up exciting new avenues of research towards an effective treatment.

"In addition to identifying those genes linked with the development of Parkinson's, this research has also shown that many of these genes were especially active in Parkinson's brains," she said.

"By limiting the activity of these genes, we may be able to control or even stop the development of Parkinson's."

Her colleague, Dr Linda Moran, also from Imperial, added: "This research shows there are a considerable number of genes associated with the development of Parkinson's, potentially providing new clues for how to treat this disease. Now that we can identify these genes it may be possible to develop new therapies to help the increasing numbers of Parkinson's patients."

News of the breakthrough came when a paper was published in the journal Neurogenetics yesterday.

The researchers analysed 23 brains from recently deceased patients, of which 15 had been affected by Parkinson's and eight came from people who did not have the condition.

They used "micro-arrays" of laboratory chips that are able to pick up which genes are active when different processes are occurring in the brain.

The team, led by Professor Manuel Graeber, investigated two parts of the brain which are affected by Parkinson's: the substantia nigra in the mid-brain and the cerebral cortex.

They were able to eliminate around 15,000 genes from any role in Parkinson's, as they were not found to be active in the substantia nigra, the part of the brain most affected by Parkinson's.

A spokeswoman for the Parkinson's Disease Society welcomed the report. "The cause of Parkinson's is generally unknown and we continue to support research in this area," she said.