WASHINGTON, July 25 (Xinhua) -- American scientists found a gene, previously thought linked only to three to four percent of people with Parkinson's disease, could play an important role in most people with the disease, providing a potential target for the treatment.

A study published on Wednesday in the journal Science Translational Medicine revealed that the gene called LRRK2 might be just as significant in the non-hereditary form of the disease.

"This discovery is extremely consequential for Parkinson's disease because it suggests that therapies currently being developed for a small group of patients may benefit everybody with the disease," said the paper's senior author J. Timothy Greenamyre, professor of neurology in the University of Pittsburgh School of Medicine.

Parkinson's has suffered as many as 10 million people worldwide and is thought to involve both genetic and environmental factors.

The researchers previously discovered that mutations in the LRRK2 gene could over-activate the protein, causing Parkinson's in a small group of people, often in a hereditary fashion.

Greenamyre and his team engineered a molecular "beacon" that attached to LRRK2 and glowed red under a microscope if the protein was active, which allowed them to find the nerve cells in which LRRK2 was active in the brain.

The researchers applied the test to postmortem brain tissue in the Parkinson's patients without mutations in LRRK2, and healthy individuals of approximately the same age.

It indicated that in "dopamine neurons," which are the brain cells most commonly affected in Parkinson's, LRRK2 was highly active in individuals affected by the disease, but not in the healthy individuals.

This suggested that LRRK2 over-activity might be important in all people with Parkinson's, not just those who have a mutation in the gene.

"LRRK2 ties together both genetic and environmental causes of Parkinson's, as we were able to show that external factors like oxidative stress or toxins can activate LRRK2, which can in turn cause Lewy bodies to form in the brain," said the paper's lead author Roberto Di Maio, an assistant professor in Greenamyre's lab.

The formation of Lewy bodies in the brain is a hallmark of Parkinson's disease.