Mitochondrial targeted tyrosyl-tRNA synthetase (YARS2) mutations cause an autosomal recessive disorder that typically presents in childhood, most often with myopathy. Researchers have now summarized salient clinical findings in a series of cases and characterize the underlying molecular defects in these patients through biochemical testing, tissue analysis, and modeling in yeast. Using a combination of next-generation sequencing techniques and gene-targeted sequencing, the investigators identified six new patients, from four pedigrees, with a rare mitochondrial syndrome caused by mutations in YARS2, and establish a likely Scottish founder effect for two of the families. They compare these new patients with 11 previously reported cases, and …