The notion that gene therapy can be used to achieve long-term correction of disease phenotypes has attracted enormous interest, yet there are few examples of success in large animals or in humans. Ponder et al. report exciting progress with a canine model of mucopolysaccharidosis VII (MPS VII), a lysosomal storage disease (Sly syndrome) caused by a deficiency in an enzyme that degrades certain sugar molecules. When dogs with MPS VII were injected as newborns with a retroviral vector encoding the missing enzyme, they showed sustained liver production of the enzyme and remained healthy and mobile for over a year. In contrast, untreated dogs at 6 months of age began to develop the major clinical features of the disease, including an inability to walk, cardiovascular disease, and corneal clouding. In principle, with further optimization, the specific gene delivery method described could be applied more generally to treat other lysosomal storage diseases, blood protein deficiencies such as hemophilia, and deficiencies of liver proteins. — PAK
Proc. Natl. Acad. Sci. U.S.A.99, 13102 (2002).