3-methylglutaconicaciduria type III

an autosomal recessive neuroophthalmologic syndrome caused by mutation in the OPA3 gene (locus: 19q13.2-q13.3), which encodes a ubiquitously expressed protein of unknown function. It is characterized by early-onset optic atrophy and later development of choreoathetosis, spasticity, cerebellar ataxia, nystagmus, and cognitive deficits; urinary excretion of 3-methylglutaconic acid is mildly increased. Called also Costeff optic atrophy syndrome.