Mutations in SLC25A4, encoding ANT1, are responsible for both the autosomal dominant and recessive cardiomyopathic type mitochondrial DNA depletion syndromes (OMIM 617184 and 615418, respectively) (Palmieri et al., 2005; Echaniz-Laguna et al., 2012; Körver-Keularts et al., 2015; Thompson et al., 2016), in addition to autosomal dominant progressive external ophthalmoplegia (OMIM 609283) (Kaukonen et al., 2000; Napoli et al., 2001; Komaki et al., 2002; Siciliano et al., 2003). Here, SLC25A4 is linked to autosomal dominant progressive external ophthalmoplegia.