Combined oxidative phosphorylation defect type 29

A rare mitochondrial oxidative phosphorylation disorder characterized by microcephaly, global developmental delay, spastic-dystonic movement disorder, intractable seizures, optic atrophy, autonomic dysfunction, and peripheral neuropathy. Serum lactate is increased, and muscle biopsy shows decreased activity of mitochondrial respiratory complexes I and III. Brain imaging reveals progressive cerebellar atrophy and delayed myelination.