Rotig et al were the first to report a family in which CoQ10 deficiency caused by PDSS2 mutation responded to CoQ10 supplement, their study involving three affected siblings.15, 19 Two siblings developed bilateral sensorineural deafness, optical and neurological symptoms, and NS resulting in terminal renal failure and required transplantation. This evidence concerns the gene PDSS2 and hyperinsulinemic hypoglycemia, familial, 4.