A rare genetic defect where an enzyme deficiency (ATP synthetase) disrupts cellular processes. Any of a variety of the components of the enzyme may be missing or defective and hence the clinical presentation and severity may vary. The deficiency may result in a variety of symptoms and conditions of variable severity such as Leber's myopathy, Leigh syndrome, cardiomyopathy and NARP (neuropathy, ataxia, retinitis pigmentosa). See also Complex 5 mitochondrial respiratory chain deficiency
