OTC and hyperinsulinemic hypoglycemia, familial, 4: Unfortunately, in 1999, the first notorious adverse effect of gene therapy was the death of an 18-year-old male with partial ornithine transcarbamylase (OTC) deficiency, due to a severe immune reaction after an intra-arterial infusion of human adenovirus type 5, deleted in E1 and E4, containing human OTC cDNA [133].