Mutations in COA7 cause spinocerebellar ataxia with axonal neuropathy

AbstractSeveral genes related to mitochondrial functions have been identified as causative genes of neuropathy or ataxia. Cytochromec oxidase assembly factor 7 (COA7) may have a role in assembling mitochondrial respiratory chain complexes that function in oxidative phosphorylation. Here we identified four unrelated patients with recessive mutations inCOA7 among a Japanese case series of 1396 patients with Charcot-Marie-Tooth disease (CMT) or other inherited peripheral neuropathies, including complex forms of CMT. We also found that all four patients had characteristic neurological features of peripheral neuropathy and ataxia with cerebellar atrophy, and some patients showed leukoencephalopathy or spinal cord atrophy on MRI scans. Validated mutations were located at highly conserved residues among different species and segregated with the disease in each family. Nerve conduction studies showed axonal sensorimotor neuropathy. Sural nerve biopsies showed chronic axonal degeneration with a marked loss of large and medium myelinated fibres. An immunohistochemical assay with an anti-COA7 antibody in the sural nerve from the control patient showed the positive expression of COA7 in the cytoplasm of Schwann cells. We also observed mildly elevated serum creatine kinase levels in all patients and the presence of a few ragged-red fibres and some cytochromec oxidase-negative fibres in a muscle biopsy obtained from one patient, which was suggestive of subclinical mitochondrial myopathy. M...
Source: Brain - Category: Neurology Source Type: research