Edison

Our definition of inherited mitochondrial respiratory chain diseases will likely need to be revisited. Substantial evidence is surfacing implicating mitochondrial dysfunction in diabetes, stroke, and neurodegenerative disease. For example, laboratory findings have identified a 1:1 correlation of the genetic parameters in Huntington’s disease patients with defects in energy generation. Analogous biochemical defects have also been seen in specialized areas of the brain in Huntington’s disease patients. These observations are not unique to Huntington’s disease.

In 1982 a surreptitious observation was made that drug addicts exposed inadvertently to MPTP– a mitochondrial toxin, developed Parkinson’s-like symptoms. This finding has been replicated in animal and cellular models of Parkinson’s disease. As MPTP inhibits proteins within the respiratory chain, a working hypothesis today for the cause of Parkinson’s disease includes defects in mitochondrial electron transport. In both Huntington’s and Parkinson’s diseases, further evidence suggesting a role of the mitochondria is disease pathogenesis is their response to antioxidants– whose action is the treatment of free radical formation secondary to mitochondrial dysfunction.

It is probable that, as we acquire more powerful research and clinical tools, our definition of what is a mitochondrial disease will be re-worked. Furthermore, it is probable that many diseases that eluded our understanding will be shown to possess a component of mitochondrial impairment. This will not be surprising given the central role energy generation and regulation plays in the function of every cell in our body.