MPV17-related Hepatocerebral Mitochondrial DNA Depletion Syndrome

Mitochondrial DNA (mtDNA) depletion syndrome comprises diseases resulting from a deficiency of proteins involved in mtDNA synthesis. MPV17 is a mitochondrial membrane protein whose mutation causes mitochondrial deoxynucleotide insufficiency. MPV17-related hepatocerebral mtDNA depletion syndrome is a rare autosomal recessive disease. This case report describes the clinical manifestations of MPV17-related hepatocerebral mtDNA depletion syndrome analyzed by performing whole-exome sequencing (WES). A 17-month-old girl presented with developmental delay, jaundice, and failure to thrive. The laboratory findings revealed cholestatic hepatitis, increased lactate-to-pyruvate ratio, and prolongation of the prothrombin time. She developed a hypoglycemic seizure. Brain magnetic resonance imaging revealed extensive demyelination of the white matter. WES detected the p.Leu151fs and p.Pro98Leu variants in MPV17. Her parents and sibling were found to be MPV17 heterozygous carriers. She was administered supportive treatment, such as replacement of fat-soluble vitamins and cornstarch to prevent further hypoglycemic events. The patient is currently being considered for liver transplantation. Overall, WES can help diagnose hepatocerebral mtDNA depletion syndrome in patients with hepatopathy, developmental delay, lactic acidosis, and hypomyelination based on brain magnetic resonance imaging.