children.webmd.com/news/20110824/gene-therapy-effective-for-bubble-boy-disease

According to this article, 14 of 16 children who received gene therapy (9 years ago in the UK) for SCID are doing well. Rather than using bone marrow transplants to treat these patients, gene therapy was helped the body to alter the DNA such that the patients were able to make their own immune systems work properly. There are still snags to be corrected, since 1 child with the X1 form of SCID ended up with leukemia.