The observation that F18L associates with a corresponding alteration in complex II_III activity in glioblastoma is consistent with our predicted effects of the F18L mutation on the three-dimensional structure of the coenzyme Q10 (CoQ10)-binding pocket (Qi-site) that lies within the mtDNA-encoded MT-CYB protein, at the heart of complex III [20]. The gene discussed is MT-CYB; the disease is glioblastoma.