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NARP syndrome: causes, symptoms, diagnosis, treatment
Last reviewed: 04.07.2025
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[ Causes and pathogenesis of NARP syndrome
The disease is based on a point mutation in the 8993 mtDNA locus, which belongs to the class of miscence mutations, when leucine is replaced by arginine in the subunit of the sixth mitochondrial ATPase. A correlation is often found between the severity of clinical manifestations of the disease and the amount of abnormal mtDNAs (heteroplasmy level).
Symptoms of NARP syndrome
Clinical signs include the main symptoms: neuropathy, ataxia, retinitis pigmentosa. Often in children, there is a delay in neuropsychic development, spasticity, progressive dementia. However, the time of manifestation of the disease varies significantly (early and late debut). The severity varies from malignant to benign forms. The course is progressive.
Diagnosis of NARP syndrome
Laboratory studies often reveal lactic acidosis, but it may not be present. Morphological examination of muscles sometimes reveals the phenomenon of "ragged" red fibers.
Differential diagnosis is carried out with conditions accompanied by ataxia and retinitis pigmentosa (olivopontocerebellar degeneration, Refsum disease, abetalipoproteinemia).
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