[A case of NARP (neurogenic muscle weakness, ataxia, and retinitis pigmentosa) with a T-to-C point mutation at nt 8993 of mitochondrial DNA].

: We report a case of NARP with a T-to-C point mutation at nt 8993 of mitochondrial DNA. A 37-year old man with mild mental retardation, retinitis pigmentosa, and clonic-tonic seizure was admitted to our hospital. The neurological examination revealed scanning speech, dystonic neck turning to the left side, and pyramidal tract signs. Serum-, CSF-lactate and pyruvate level were slightly elevated. Brain MRI findings showed cerebral atrophy, cerebellar cortical atrophy accompanied with dilation of forth ventricle, and high intensity lesions in the bilateral lenticular nuclei on T2 weighted images. Nucleotide sequence analysis of the mitochondrial DNA in the leukocytes demonstrated a T-to-C point mutation at nt 8993. To our knowledge, this is the first report of a Japanese patient with NARP associated with the T-to-C mutation at nt 8993 of mt DNA. Mitochondrial DNA analysis should be considered in the differential diagnosis of patients with retinitis pigmentosa and various neurological signs.