NARP
NARP / Neuropathy, Ataxia, Retinitis pigmentosa, MTATP6, MTATP8
Clinical Features
Most patients with NARP syndrome develop a slowly progressive peripheral neuropathy and ataxia in adult age. Retinal pigment degeneration is almost exclusively present. The rate of heteroplasmy has a strong influence on the clinical presentation.
Genetic Information
The cause of the NARP syndrome is the T8993G or T8993C mutation in the mitochondrial ATPase6 gene. If this mutation present >90% in blood DNA, the clinical picture is a maternal inherited Leigh syndrome, if the mutation rate is 70-90%, the phenotype is NARP.
Autosomal inherited mutations in the nuclear-encoded POLG1 gene may also lead to the clinical presentation of a NARP syndrome. In muscle DNA of patients with POLG1 mutations, multiple mtDNA deletions are usually present.
Prevalence
Not yet known
Diagnostic
Indication
Method
1. Mutation analysis for the mtDNA ATPase6 Mutation (T8993G/C) by DNA sequencing
2. Mutation analysis for other mtDNA ATPase6 or ATPase8 mutations by DNA sequencing.
3. Mutation analysis of the entire coding and flanking intronic regions with intronic primers of the POLG1 gene by direct DNA sequencing
Sample Requirement
2 - 4 ml of EDTA-blood
Duration
1.: 2 - 3 weeks
2.+3.: 4 - 6 weeks