The roles of mitochondrial tRNA mutations in non-dystrophic myotonias.

According a recent report by Heidari et al., a mutational screening for candidate pathogenic mitochondrial tRNA (mt-tRNA) mutations were performed in 45 Iranian patients with non-dystrophic myotonia (NDM) and 70 control subjects. Through PCR amplification and direct sequence analysis, nine mt-tRNA mutations were identified: tRNA T4454C, tRNA A5568G, tRNA T5794C, tRNA A10438T and T10462C, tRNA A12308G, tRNA A15907G, A15924G and G15928A. However, through the database searches and phylogenetic conservation analysis, we noticed that the tRNA A15924G, G15928A and tRNA A12308G mutations should be classified 'pathogenic'. Thus, the roles of mt-tRNA mutations in clinical expression of NDM needed to be further experimentally addressed.