OPA1 and mitochondrial disease: We could not find any pathogenic mutations in other genes known to cause mitochondrial diseases with multiple mtDNA deletions (POLG1, POLG2 (MIM 604983), C10orf2 (MIM 606075), SLC25A4 (MIM 103220), OPA1 (MIM 605290), TYMP (MIM 131222) and WFS1 (MIM 606201)) in exome analysis, as was observed in a previous study using Sanger sequencing [4].