- Deficiency of the reduced nicotinamide adenine dinucleotide dehydrogenase component of complex I of mitochondrial electron transport. Fatal infantile lactic acidosis and hypermetabolism with skeletal-cardiac myopathy and encephalopathy. Hoppel, C.L., Kerr, D.S., Dahms, B., Roessmann, U. J. Clin. Invest. (1987)