A novel COQ7 mutation causing primarily neuromuscular pathology and its treatment options

Abstract

Coenzyme Q10 (CoQ10) is necessary as electron transporter in mitochondrial respiration and other cellular functions. CoQ10 is synthesized by all cells and defects in the synthesis pathway result in primary CoQ10 deficiency that frequently leads to severe mitochondrial disease syndrome. CoQ10 is exceedingly hydrophobic, insoluble, and poorly bioavailable, with the result that dietary CoQ10 supplementation produces no or only minimal relief for patients. We studied a patient from Turkey and identified and characterized a new mutation in the CoQ10 biosynthetic gene COQ7 (c.161G > A; p.Arg54Gln). We find that unexpected neuromuscular pathology can accompany CoQ10 deficiency caused by a COQ7 mutation. We also show that by-passing the need for COQ7 by providing the unnatural precursor 2,4-dihydroxybenzoic acid, as has been proposed, is unlikely to be an effective and safe therapeutic option. In contrast, we show for the first time in human patient cells that the respiratory defect resulting from CoQ10 deficiency is rescued by providing CoQ10 formulated with caspofungin (CF/CoQ). Caspofungin is a clinically approved intravenous fungicide whose surfactant properties lead to CoQ10 micellization, complete water solubilization, and efficient uptake by cells and organs in animal studies. These findings reinforce the possibility of using CF/CoQ in the clinical treatment of CoQ10-deficient patients.