The promise has always been there for gene therapies. Unfortunately, the field has seen a number of false starts for the expected explosion of investment and business development around treatments that correct for faulty genes. The breakthrough appeared to have been made following the European approval of Glybera (alipogene tiparvovec, Uniqure BV), for the treatment of the ultra-orphan metabolic disease lipoprotein lipase deficiency (LPL). But, while the medicine was widely heralded as the "first gene therapy" in the Western world, it failed to take off and its developer subsequently abandoned plans to have it approved in the U.S.