The m.5650G>A mitochondrial tRNAAla mutation is pathogenic and causes a phenotype of pure myopathy.

We report a family where a predominantly proximal myopathy has become increasingly severe with successive generations of the maternal lineage. This pure myopathy has been caused by a mutation (m.5650G>A) in the mt-tRNA(Ala) gene that has been reported only once previously in a patient with CADASIL where the phenotype was dominated by neurological complications. This report is therefore the first description of the phenotype associated solely with this mutation and confirms its pathogenicity.