Developmental regression, Diabetes mellitus, Dyskinesia, Dystonia, Encephalopathy, Exercise intolerance, Failure to thrive, Feeding difficulties, Feeding difficulties in infancy, Fetal distress, Flexion contracture, Focal T2 hyperintense brainstem lesion, Generalized hypotonia, Global developmental delay, Growth delay, Hearing impairment, Hepatic failure, Hepatomegaly, Hyperreflexia, Hypertrophic cardiomyopathy, Hypoglycemia, Hyporeflexia, Hypotonia, Increased CSF lactate, Increased serum pyruvate, Intrauterine growth retardation, Irritability, Kyphosis, Lactic acidosis, Lethargy, Leukodystrophy, Leukoencephalopathy, Metabolic acidosis, Microcephaly, Mitochondrial myopathy, Muscle weakness, Myopathy, Nystagmus, Optic atrophy, Optic disc pallor, Optic neuropathy, Paroxysmal involuntary eye movements, Peripheral demyelination, Poor eye contact, Poor head control, Progressive macrocephaly, Proximal tubulopathy, Ptosis, Respiratory insufficiency, Seizure, Sensorineural hearing impairment, Skeletal muscle atrophy, Spastic tetraplegia, Spasticity, Strabismus, Vomiting