PTC124 has been successfully used in treatment of arylsulfatase B (ARSB associated mucopolysaccharidosis) (69) and PTC124 is currently in clinical trials for the treatment of cystic fibrosis (70) and Duchenne muscular dystrophy (46); however, the clinical findings of these studies are not conclusive. The gene discussed is PPIB; the disease is mucopolysaccharidosis.