Point Mutations on Mitochondrial DNA in Iranian Patients with Friedreich’s Ataxia

Objective

Mitochondrial DNA (mtDNA) is considered a candidate modifier factor for neuro-degenerative disorders. The most common type of ataxia is Friedreich's ataxia (FA). The aim of this study was to investigate different parts of mtDNA in 20 Iranian FA patients and 80 age-matched controls by polymerase chain reaction (PCR) and automated DNA sequencing methods to find any probable point mutations involved in the pathogenesis of FA.

Materials and Methods

We identified 13 nucleotide substitutions including A3505G, T3335C, G3421A, G8251A, A8563G, A8563G, G8584A, T8614C, T8598C, C8684T, A8701G, G8994A and A9024G.

Results

Twelve of 13 nucleotide substitutions had already been reported as polymorphism. One of the nucleotide substitutions (A9024G) had not been reported before. The A9024G nucleotide substitution does not change its amino acid. The controls were also investigated for this polymorphism which was found in two of them (2.5%).

Conclusion

None of the mutations found in this study can affect the clinical manifestations of FA. This survey also provides evidence that the mtDNA A9024G allele is a new nonpathogenic polymorphism. We suggest follow-up studies for this polymorphism in different populations.