For children who have ADA-SCID, a treatment called PEG-ADA is available. Children with ADA-SCID lack an important enzyme which helps their immune system function. In PEG-ADA therapy, children with ADA-SCID receive at least weekly intramuscular injections of a drug containing the missing enzyme, adenosine deaminase, or ADA. These injections allow the immune system to function.
One of the drawbacks is that the PEG-ADA treatments require painful weekly injections into the muscle for the rest of the child’s life. There is also a possibility that treatment will not be as effective over time as the child gets older. PEG-ADA can also be expensive, sometimes costing hundreds of thousands of dollars a year.
Overall, it is generally accepted that PEG-ADA is a sufficient temporary treatment but not a long-term solution to the health challenges presented by SCID.