Prominent examples of genetically caused MCM include the Barth syndrome, caused by a mutation in the TAFAZZIN (TAZ) gene (Dudek and Maack, 2017), Friedreich’s ataxia, caused by a mutation in the FRATAXIN(FXN) gene (Punga and Buhler, 2010) and propionic acidemia, caused by a mutation in the enzyme propionyl-CoA carboxylase (Wongkittichote et al., 2017). Here, FXN is linked to Barth syndrome.