Neuropathy, Ataxia, and Retinitis Pigmentosa
Neuropathy, ataxia, and retinitis pigmentosa (NARP) is associated with a single base-pair mutation at nucleotide position 8993 in the ATPase-6 gene. The NARP phenotype occurs when the percentage of mutant mtDNA is less than 80%, whereas the same mutation present at much higher proportions (greater than 95%) can cause Leigh syndrome, a severe neurodegenerative disease of infancy and early childhood. The 8993 mutation is demonstrable in fibroblasts and lymphoblasts.
Excerpted from BCSC 2020-2021 series: Section 2 - Fundamentals and Principles of Ophthalmology. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.