Parkinson's disease and melanoma may be linked

By Karla Gale

NEW YORK, 18 feb 2009– When there's melanoma in the family, there may also be Parkinson's disease, researchers report.

They found that a family history of melanoma seems to be tied to a genetic susceptibility to develop Parkinson's disease. The findings are due to be presented on May 1 at the American Academy of Neurology's annual meeting in Seattle.

"Co-occurrence of Parkinson's disease and melanoma has been reported in numerous studies," Dr. Xiang Gao told Reuters Health. "Our study is the first to show that this co-occurrence could be due to common genetic mechanisms between these two conditions."

Gao, of Harvard School of Public Health, Boston, and colleagues analyzed data from two ongoing studies -- the all-male Health Professional Follow-up Study and the all-female Nurses Health Study.

All the subjects -- nearly 132,000 men and women -- were free of Parkinson's disease at the start of the studies but over the next 14 to 20 years, 543 cases occurred.

The participants had provided information on any cases of melanoma in their parents or siblings. The investigators found that a family history of melanoma almost doubled likelihood of developing Parkinson's disease.

It's likely that melanoma and Parkinson's disease share common genetic components, the investigators conclude.

As to the possible mechanism underlying the two conditions, Gao said, "The metabolism of pigments, and genes that encode the proteins in this process, may, at least in part, explain this association."

His group has recently shown that individuals with red hair color or a variant of a pigmentation gene called MC1R were about 2 or 3 times more likely to develop Parkinson's disease. "Both red hair color and MC1R gene are well established risk factors for melanoma," Gao explained.

It will be important to confirm the findings in other populations, the researcher added. "Our findings, if confirmed, will help clinicians to identify high-risk populations for Parkinson's disease."