MITOCHONDRIAL DISORDERS - METHODS AND SPECIMEN SELECTION FOR DIAGNOSTIC MOLECULAR PATHOLOGY

Mitochondrial DNA is a circular double-stranded macromolecule. Each st rand contains 16569 base pairs. Mutations in mitochondrial DNA, includ ing base substitutions in tRNA or rRNA genes, deletions, duplications, or base substitutions in genes for protein subunits, lead to specific diseases. The ratio of mutated to normal mitochondrial DNA may vary f rom tissue to tissue (heteroplasmy) in mitochondrial DNA diseases. The refore, the source of the specimen is important in the evaluation of m itochondrial DNA mutations. Detection method selection is also critica l. For example, single-strand conformation polymorphism is not as spec ific for tRNA mutations as is gene sequencing or amplification of a sp ecific gene by polymerase chain reaction. Care in both specimen collec tion and analytic method are important in the successful evaluation of patients with a potential mitochondrial DNA disease.