Autosomal-dominant POLG2-related mitochondrial disorder (progressive external ophthalmoplegia with mitochondrial DNA deletions, autosomal dominant 4; PEOA4) was indicated as a diagnosis by identifying heterozygosity for the novel truncating POLG2 variant c.886G>T (p.Gly296*) by WES in P5 and by its segregation with the mitochondriopathy-phenotype in this family. Here, POLG2 is linked to progressive external ophthalmoplegia.