NARP syndrome in a patient harbouring an insertion in the MT-ATP6 gene that results in a truncated protein.

Abstract

Neurogenic muscle weakness, ataxia and retinitis pigmentosa (NARP) syndrome have been associated to m.8993T>G/C mutations in the subunit 6 of the ATP synthase (p.MT-ATP6). We have performed a mutational screening of the mitochondrial DNA gene encoding for this protein in 62 patients with the disease, that do not carry any of the common mutations described to date. We report clinical and molecular data in one patient who harbours a de novo insertion in the MT-ATP6 gene that results in a truncated subunit. The mutation was heteroplasmic (85%) in muscle DNA and the BN-PAGE analysis showed a clear decrease in the amount of ATP synthase. Molecular analysis of NARP patients cannot be limited to the search of the m.8993T>G/C and either the ATP6 or the whole mtDNA should be sequenced.