First, the authors mentioned polyneuropathy in the neuropathy, ataxia, and retinitis pigmentosa (NARP) syndrome and Leigh's syndrome and suggested that both of the phenotypes presented with polyneuropathy of the axonal type. However, in 1986, Goebel et al.2 reported demyelinating neuropathy with sural nerve biopsies in four unrelated children in whom the diagnosis of Leigh's disease was verified at autopsy and reviewed 13 previously reported peripheral neuropathy cases in Leigh's disease with the evidence of demyelination in …