In Parkinson's disease, certain neurons make too little dopamine, a chemical that helps the brain control movement.

A new study in the journal Nature Neuroscience identifies a neuron subtype that appears to be especially vulnerable — and important for disease risk.

"We didn't understand what was different about those cells that die, versus the very similar cells nearby that also make dopamine but don't seem to be as vulnerable to Parkinson's disease," said senior author Evan Macosko of the Broad Institute of Harvard and MIT.

By studying how more than 20,000 cells carried out DNA instructions, researchers discovered 10 distinct subtypes of dopamine neurons, one of which strongly raises Parkinson's disease risk.

Those same neurons tended to disappear from the brains of people with the disease, suggesting the subtype is especially vulnerable.

That knowledge could help researchers develop better screening tools or improve treatments like cell replacement therapy.

“There’s a lot of efforts to undertake cell replacement therapies for Parkinson's disease, where we try to grow neurons in a dish and then transplant them into patients who are suffering from this illness," said Macosko. "And these data kind of provide a roadmap for making the neurons that are necessary to replace.”

Macosko added that the findings could also help scientists better understand how the genes in these specific cells become misregulated and die.

"We think those pathways are really key candidates for making therapeutics — drugs that could potentially target those pathways and slow down the death process," he said.