Nonsense mutations are single-letter errors in the genetic code that prematurely halt the production of critical proteins. These unfinished proteins are unable to function normally, and nonsense mutations cause 10-15 percent of all inherited genetic diseases, including Duchenne muscular dystrophy, spinal muscular atrophy, cystic fibrosis and polycystic kidney disease. There is currently no cure or broadly effective treatment for these often devastating conditions that are individually rare but estimated to collectively affect up to 30 million people worldwide.