Inherited mitochondrial diseases are genetic disorders that share as a common link defects in how cells make and regulate energy. They can arise through defects in genes located in the nucleus or mitochondria. An estimated 2,000 defects in nuclear DNA and 200 defects in mitochondrial DNA have been identified that are pathogenic.
Owing to the central role the mitochondria plays in the generation and regulation of energy metabolism, mitochondrial diseases affect virtually all organ systems. Clinical manifestations often center on devastating neurological impairments; but cardiac, endocrine, hepatic, muscular, and renal insufficiency also contribute to significant morbidity and mortality.
The incidence of mitochondrial disease is estimated at 1-5 in 10,000. However, this number may underestimate the true number of people with mitochondrial disease. While genetic screening tools have made detection of mitochondrial disease possible, the majority of individuals with a clinical diagnosis of mitochondrial disease may not have a confirmatory genetic diagnosis. Some estimates place the number of clinically diagnosed mitochondrial disease patients without a genetic diagnosis– so-called mitochondrial syndromes– at 5-10 times the reported incidence of genetically defined disease.
Inherited mitochondrial diseases are clinically diverse and, with few exceptions, have variable and generally poorly characterized natural histories. Development of drugs for these conditions is complicated by the rare (orphan) nature of mitochondrial diseases. In some cases, as few as 10 subjects have been identified with a common genotype.
Unraveling the basic science of mitochondrial disease holds two promises. First, drugs can be developed to treat a family of devastating diseases. Second, we gain insights into the basic underpinninings of how our bodies make and regulate energy metabolism. Edison researchers believe that the emerging field of mitochondrial medicines will open up these very important medical and scientific areas of investigation and provide key insights into the biology of aging.