Mutations in COQ2 genecause primarydeficiency of Coenzyme Q10 (CoQ10, CoQ), due to a defect in the production of this molecule, necessary for cell energy production and for preventing oxidative stress, which causes cell to age and die. As different mutations cause different clinical pictures, it has been proposed that the severity of the diseases depend on the amount of CoQ produced. COQ2 mutations which allow some residual activity of COQ2 are associated with the milder phenotypes and vice versa.
COQ2