New variants expand the neurological phenotype of COQ7 deficiency.

The protein encoded by COQ7 is required for CoQ synthesis in humans, hydroxylating 3-demethoxyubiquinol (DMQ) in the second to last steps of the pathway. COQ7 mutations lead to a primary CoQ deficiency syndrome associated with a pleiotropic neurological disorder. This study shows the clinical, physiological, and molecular characterization of four new cases of CoQ primary deficiency caused by five mutations in COQ7, three of which have not yet been described, inducing mitochondrial dysfunction in all patients.

Secondary CoQ deficiency, bioenergetics unbalance in disease and aging.

Coenzyme Q (CoQ ) deficiency is a rare disease characterized by a decreased accumulation of CoQ in cell membranes. Considering that CoQ synthesis and most of its functions are carried out in mitochondria, CoQ deficiency cases are usually considered a mitochondrial disease. A relevant feature of CoQ deficiency is that it is the only mitochondrial disease with a successful therapy available, the CoQ supplementation.