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A number of recent scientific studies have suggested that people affected by Parkinson's disease have defects in mitochondria, the cellular components that produce energy for the body. Studies in rats have shown that chronic exposure to the common pesticide rotenone can cause damage to the energy producing proteins in the mitochondria and induce symptoms that mimic Parkinson's disease in people. These proteins, which together are called complex I, are among the few genes encoded in the genetic material of the mitochondria itself.
A recent study from Duke University looked at why mitochondria have been implicated in Parkinson's disease. Researchers decided to examine whether common gene variations called haplogroups that exist in the complex I proteins could change a person's susceptibility to developing Parkinson's disease.
The scientists examined the mitochondrial DNA of 609 Parkinson's disease patients and 340 normal controls who had no signs of the disease. In particular, they looked at nine well-known and well-studied gene variations that vary among ethnic groups. When they looked at the correlation between gene variation and incidence of Parkinson's disease, they discovered that one variant, called "J" was much more common in people who do not have Parkinson's disease, and particularly among women.
It seems tht the J haplogroup is much more common in unaffected individuals, so that research would suggest that it is protective. The J variant is found in about 26 percent of Caucasians, versus two-thirds of Asians and more than 90 percent of sub-Saharan Africans. However, the researchers noted that since they only studied Caucasians in this study, they could venture no conclusion about whether the J variant is protective in other ethnic groups.
It is interesting, however, that this protective allele is more common in the groups that are thought to have a lower incidence of Parkinson disease, the inherited gene variations seem particularly to protect white women, which may help explain why Parkinson's disease is seen more often in men.
Further research should help clarify the gene's protective effect.
Other recent related research
Mechanistic approaches to Parkinson's disease pathogenesis
Brain Pathol. 2002 Oct;12(4):499-510. Review.
Activation of mitochondrial ATP-sensitive potassium channels increases cell viability against rotenone-induced cell death.
J Neurochem. 2003 Mar;84(5):1193-200
Bioenergetic approaches for neuroprotection in Parkinson's disease.
Ann Neurol. 2003;53(3 Suppl 1):S39-48.
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