An experimental gene therapy has successfully treated 62 children with ADA-SCID, a fatal immune disorder. The treatment involves modifying the child's blood stem cells to produce healthy immune cells. Results show stable immune functions and no serious complications for most patients. The study is the largest of its kind, with hopes for FDA approval in the next few years. The therapy has significantly improved the lives of children like Eliana Nachem, who now enjoys a normal childhood after treatment.