COX8A and hyperinsulinemic hypoglycemia, familial, 4: The potential of BZ has also been evaluated in vivo in several mouse models of COX deficiency: i.e., a Surf1 constitutive knockout (KO) mouse [129], a muscle-specific Cox15 KO mouse [129], the “Deletor” mouse overexpressing a mutant replicative helicase Twinkle [130], and the Mutator mouse expressing a mutant mtDNA polymerase γ [131].