Given the mitochondrial disease phenotype in Patient 2 (P2) that appeared to have hallmarks of the GRACILE syndrome associated with defects in BCS1L and abnormal liver function previously concomitant with MPV17-related hepatocerebral mitochondrial DNA depletion syndrome, candidate gene sequencing for variants in BCS1L and MPV17 was performed on genomic DNA isolated from P2. Here, MPV17 is linked to inborn mitochondrial metabolism disorder.