Discovered in the mid-1960s, adenoassociated viruses (AAVs) have become the leading vector for gene therapy in recent years. In October 2012, the first European market authorization for a human gene-therapy product was granted for UniQure’s Glybera (alipogene tiparvovec), which contains an AAV1 vector for treating patients who have lipoprotein lipase deficiency. (The product has been withdrawn from the market because of limited demand.) Both gene therapies currently approved in the United States — Luxturna (voretigene neparvovec) from Spark Therapeutics, approved…