A 4-base pair deletion in the mitochondrial cytochrome b gene associated with parkinsonism/MELAS overlap syndrome

Five patients with diminished activity of complex III of the mitochondrial respiratory chain have been screened for mutations in the mitochondrial cyt ochrome b (cyt b) gene. In 1 patient, a young boy with an akinetic rigid sy ndrome and a mitochondrial encephalomyopathy with lactic acidosis and strok e-like episodes (MELAS), a novel 4-base pair deletion was identified, This mutation in this highly conserved gene is considered to be pathogenic since it is a heteroplasmic frame shift mutation predicted to lead to a truncate d protein.