Test Details: Neuropathy ataxia retinitis pigmentosa (NARP) syndrome is characterized by a variety of signs and symptoms that mainly affect the nervous system. It is a rare inherited disorder associated with T8993G mutation in mitochondrial DNA (mtDNA). NARP is characterized by sensory neuropathy, developmental delay and pigmentary retinopathy. Symptomatic mitochondrial disease generally reflect the presence of 70-80% mutant mitochondrial DNA in the cells. PCR is used in diagnostic testing for NARP by mutation analysis of mitochondrial ATP6 gene followed by direct nucleotide sequencing of the PCR products. The specificity of the assay is >98% and sensitivity is 99.9% due to presence of excess mtDNA in every cell.