Mitochondrial Gene Variation Linked to Parkinson's Disease

Researchers have identified a single-nucleotide polymorphism (SNP) in the genetic material located within the mitochondria of cells from individuals with Parkinson's disease that may increase the likelihood of developing the disorder.

Earlier studies had demonstrated a relationship between mitochondria and Parkinson's disease. To further study this linkage, investigators from the Duke University Medical Center (Durham, NC, USA) examined the mitochondrial DNA of 609 Parkinson's disease patients and 340 normal controls with no signs of the disease. They found that one variant, called the "J” variant, was much more common in people who did not have Parkinson's disease, particularly among women. The J variant is found in about 26% of Caucasians, versus two-thirds of Asians and more than 90% of sub-Saharan Africans. The J variant codes for a protein that differs from the more common variant by only one amino acid, threonine instead of alanine. These findings were published in the April 2003 issue of the American Journal of Human Genetics.

"The J haplogroup is much more common in unaffected individuals, so that would suggest it is protective,” said senior author Dr. Jeffery Vance, professor in the department of medicine at Duke University. "The genetic risk factors for Parkinson's disease have been difficult to study because it is a complex disease that likely has both genetic and environmental components. We are finding that Parkinson's disease is not one disease; it is many diseases.”