NARP Syndrome: A 20-Year Follow-Up

One member of a pedigree with NARP syndrome (neurogenic weakness, ataxia, and retinitis pigmentosa), a mitochondrial disorder due to a point mutation at position 8993 in the mitochondrial genome ATPase 6 gene, was reevaluated some 20 years after first being reported in the medical literature. Initially assessed at age 39 years, she had retinitis pigmentosa and a mild sensory axonal neuropathy, typical features of NARP, but was otherwise clinically normal. At age 59 years, she was registered blind, had sensorineural hearing impairment, had recently been diagnosed with diabetes mellitus, and may have had some mild cognitive impairment. This case shows that the clinical phenotype of NARP due to mitochondrial dysfunction may evolve over a period of decades.