Recently homozygous mutations in ABAT have also been linked to a new form of mitochondrial DNA depletion syndrome which presents in combination with a neurometabolic disorder of GABA degradation that shares phenotypic overlap with individuals with mutations in SUCLG1, SUCLA2, and ALDH5A1. 5Mutations causing this type of ABAT deficiency lead to elevated levels of GABA in the brain as well as hallmarks of mitochondrial dysfunction in muscle.5 This evidence concerns the gene ABAT and mitochondrial DNA depletion syndrome.