Mitochondrial Diseases

Mitochondrial diseases are a genetically and clinically heterogeneous group of disorders that arise as a consequence of dysfunction of the mitochondrial respiratory chain. The estimate for the prevalence of all mitochondrial disorders 1:8500, but they are thought to be greatly under-diagnosed. Mitochondrial disorders can be caused by mutations of nuclear or mitochondrial DNA (mtDNA). If nuclear gene defects may be inherited in an autosomal recessive or autosomal dominant manner, mtDNA defects are transmitted only maternally. As the female could have heteroplasmic mtDNA mutations, which could be transmitted unequally to her offspring, the sibs could exhibit considerable clinical variability.

Symptoms of the mitochondrial disease can begin at any age. Mitochondrial disorders may affect a single organ (e.g. Leber hereditary optic neuropathy, LHON) or involve multiple organ systems (e.g. Myoclonic epilepsy with ragged-red fibers, MERRF). Common clinical features of mitochondrial disorder include, for example muscle weakness, exercise intolerance, trouble with balance and coordination, sensorineural deafness, impaired vision, seizures and learning deficits, cardiomyopathy, diabetes mellitus, stunted growth, and a high incidence of mid- and late pregnancy loss.

 

> Ordering information for mitochondrial genome sequencing

> Ordering information for nuclear genes NGS panel

> Ordering information for ACADS gene sequencing

> Ordering information for ACADVL gene sequencing

> Ordering information for MELAS syndrome targeted mutation analysis

 

Indications for genetic testing:

1. Diagnosis of patients with phenotype characteristic for mitochondrial disease
2. Diagnosis of patients with family history suggestive for mitochondrial disease
3. Genetic counseling of individuals with mitochondrial disease and affected family members

 

References:

Wallace DC. Mitochondrial diseases in man and mouse. Science. 1999;283:1482–8.
Chinnery PF. Mitochondrial Disorders Overview. Pagon RA, Adam MP, Bird TD, et al., editors. Seattle (WA): University of Washington, Seattle; 1993-2013.
DiMauro S, Schon EA. Nuclear power and mitochondrial disease. Nat Genet. 1998;19:214–5.
Leonard JV, Schapira AVH. Mitochondrial respiratory chain disorders I: mitochondrial DNA defects. Lancet. 2000a;355:299–304.
Leonard JV, Schapira AVH. Mitochondrial respiratory chain disorders II: neurodegenerative disorders and nuclear gene defects. Lancet. 2000b;355:389–94.