Neuropathy ataxia retinitis pigmentosa (NARP) syndrome
mainly affects the nervous system. Beginning in childhood or early adulthood, most people with NARP experience numbness, tingling, or pain in the arms and legs (sensory neuropathy); muscle weakness; and problems with balance and coordination (ataxia). Affected individuals may also have vision loss caused by a condition called retinitis pigmentosa. Other features of NARP include learning disabilities, developmental delay, seizures, dementia, hearing loss, and cardiac conduction defects. Mutations in the MT-ATP6 gene cause NARP syndrome. This gene is located contained within mitochondrial DNA. Most individuals with NARP have a specific MT-ATP6 mutation in 70 percent to 90 percent of their mitochondria. NARP syndrome is inherited from the mother because only females pass mitochondrial DNA to their children. Source: Genetic and Rare Diseases Information Center (GARD), supported by ORDR-NCATS and NHGRI.