A novel mitochondrial m.4414T > C MT-TM gene variant causing progressive external ophthalmoplegia and myopathy

Mitochondrial disorders are clinically and genetically heterogeneous and are caused by mutations in genes of both mitochondrial DNA (mtDNA) and nuclear DNA. Of the mtDNA point mutations causing mitochondrial disease, ∼50% involve mitochondrial (mt-)tRNA genes [1–3]. Pathogenic mt-tRNA mutations typically display heteroplasmy, the presence of both wild type and mutant mtDNA molecules in a cell, and are often associated with the presence of focal ragged red fibres (RRFs) and cytochrome c oxidase (COX)-deficien t fibres in skeletal muscle, leading to a combined respiratory chain deficiency reflecting a disorder of generalised mitochondrial translation.

Source: Neuromuscular Disorders - August 20, 2019 Category: Neurology Authors: Debby M.E.I. Hellebrekers, Emma L. Blakely, Alexandra T.M. Hendrickx, Steven A. Hardy, Sila Hopton, Gavin Falkous, Irenaeus F.M. de Coo, Hubert J.M. Smeets, Nadine M.E. van der Beek, Robert W. Taylor Source Type: research