This phenotypic association of peripheral neuropathy with optic atrophy is also present in hereditary motor and sensory neuropathy type VI with optic atrophy (OMIM 601152) caused by mutations in mitofuscin 2 (MFN2) [10], encoding another mitochondrial protein, emphasizing the important role of mitochondrial function for optic atrophies and peripheral neuropathies. The gene discussed is MFN2; the disease is hereditary optic atrophy.