Mutations in human FBXL4 cause mitochondrial DNA depletion syndrome 13 (MTDPS13) a severe pathology characterized by encephalopathy, stunted growth, and metabolic deficiencies (Bonnen et al, 2013; Gai et al, 2013; Dai et al, 2017; Ballout et al, 2019). This evidence concerns the gene FBXL4 and mitochondrial DNA depletion syndrome 13.