Leukoencephalopathy-dystonia-motor neuropathy syndrome is a peroxisomal neurodegenerative disorder characterized by spasmodic torticollis, dystonic head tremor, intention tremor, nystagmus, hyposmia, and hypergonadotrophic hypogonadism with azoospermia. Slight cerebellar signs (left-sided intention tremor, balance and gait impairment) are also noted. Magnetic resonance imaging (MRI) shows bilateral hyperintense signals in the thalamus, butterfly-like lesions in the pons, and lesions in the occipital region, whereas nerve conduction studies of the lower extremities shows a predominantly motor and slight sensory neuropathy.

Mitochondrial complex IV deficiency nuclear type 3 (MC4DN3) is an autosomal recessive multisystem metabolic disorder with a highly variable phenotype. Some patients present with encephalomyopathic features in early infancy, whereas others may present later in infancy or the first years of life after normal early development. Affected individuals show hypotonia, failure to thrive, and developmental delay or regression with poor eye contact and loss of motor skills with ataxia. Additional features observed in some patients include proximal renal tubulopathy, macrocytic anemia, sensorineural hearing loss, nystagmus, and hypertrophic cardiomyopathy, consistent with systemic involvement. Brain imaging in most patients shows lesions consistent with Leigh syndrome (see 256000). Laboratory studies show increased serum lactate and decreased levels and activity of mitochondrial respiratory complex IV. Most patients die in infancy (summary by Valnot et al., 2000 and Antonicka et al., 2003). For a discussion of genetic heterogeneity of mitochondrial complex IV (cytochrome c oxidase) deficiency, see 220110.

Combined oxidative phosphorylation deficiency-51 (COXPD51) is an autosomal recessive disorder characterized by a Leigh syndrome phenotype (see 256000). For a discussion of genetic heterogeneity of combined oxidative phosphorylation deficiency, see COXPD1 (609060).