Investigators at Children's Hospital Boston are ramping up a small trial of a new gene therapy to treat "bubble boy syndrome." The scientists plan to recruit 20 boys with SCID-X1, a rare genetic condition that leaves them unable to fight germs. A gene therapy trial for the disease had to be halted seven years ago after several patients developed leukemia, a major blow for the gene therapy field. Now researchers say they believe they have eliminated the threat of leukemia and are advancing a new gene treatment that could apply to other rare diseases as well. Story