Jada Bascom Foundation
All conditions

Inherited immune disorders

Adenosine deaminase-deficient severe combined immunodeficiency

Also called: ADA-SCID · ADA deficiency · ADA-deficient SCID · SCID · bubble boy disease · Severe combined immunodeficiency due to ADA deficiency · Adenosine deaminase deficiency with SCID

What a donor has to do with this

An approved gene or cell therapy now exists for this condition and can be an alternative to a donor transplant. Which route fits a person depends on their situation, and that decision belongs to them and their treating team.

This is our reading of published transplant guidelines for this condition, not a measurement of how many people need a donor. Where a source actually counted donors, the figure and the people it counted are shown further down. Where none did, we say so rather than estimate.

What the evidence says

Who it affects
Typical onset/diagnosis: classic ADA-SCID usually presents in the first 6 months, while 15–20% present at ages 1–10 years or later. Evidence: U.S. NIH GARD synthesis (updated 2026); no markedly enriched population was identified.
Treatments other than a transplant
Strimvelis (autologous CD34+ gene therapy) — approved — European Union, 2016 — For ADA-SCID without a suitable HLA-matched related donor; availability is geographically restricted.; PEGylated ADA enzyme replacement — approved/supportive bridge — multiple regions — Restores detoxification but is generally a bridge or fallback rather than definitive immune reconstitution.
If a transplant is used, the cells come from
bone marrow: used in opened IEI transplant guidance; disease-specific share was not reported; mobilized peripheral blood stem cells: used in opened IEI transplant guidance; disease-specific share was not reported; umbilical cord blood: used as an alternative in opened IEI transplant guidance; disease-specific share was not reported; dominance: no dominant graft source was reported in the opened disease-specific sources
How often the donor was unrelated
Not reported. No source we could read states this for this condition, so we do not give a number. An estimate here would be a guess dressed as evidence.

Where this gets complicated

ADA deficiency can also present as delayed-onset combined immunodeficiency or partial enzyme deficiency; those phenotypes should not automatically be counted as transplant candidates.; The 2021 guideline predates several later access and commercialization changes, so Strimvelis availability must be checked locally.

Written for transplant clinicians, not for patients. We quote it so you can see what the guidance actually says:
“In ADA-deficiency three therapeutic options are available including Enzyme replacement Therapy (ERT) and gammaretroviral gene therapy”

It describes what teams consider in general. It cannot say what applies to any one person. Read the source.

We are not asking you to register on this page

An unrelated donor is not a usual part of treating this condition, so it would be dishonest to use this page to ask you to register. Other conditions in the library are a different story.

Related conditions

Others in inherited immune disorders. They are genuinely different diseases with different treatments — the group name is not a diagnosis.

Where this came from