Inherited immune disorders
X-linked lymphoproliferative disease type 1 due to SH2D1A deficiency
Also called: XLP1 · XLP-1 · SH2D1A deficiency · SAP deficiency · Duncan disease · X-linked lymphoproliferative syndrome type 1
What a donor has to do with this
For some people with this condition, a transplant using blood stem cells from an unrelated donor is part of the treatment guidelines. When a transplant is the right route and no one in the family matches, that donor comes from a registry. Not everyone with this condition has a transplant, and many never need one.
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: disease occurs almost exclusively in males, with variable onset from infancy through adulthood. Evidence: U.S. NIH GARD synthesis (updated 2026); no markedly enriched geographic population was identified.
- Treatments other than a transplant
- Rituximab, immunoglobulin replacement, and HLH- or lymphoma-directed therapy — bridge/noncurative management — multiple regions — Does not remove future EBV-triggered HLH or lymphoma risk.
- 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
GARD's umbrella XLP page includes both XLP1 and XLP2; the census deliberately splits SH2D1A and XIAP because phenotype and conditioning risk differ.; Whether to transplant an asymptomatic molecularly diagnosed boy before EBV exposure remains individualized.
People with this condition need donors
Joining a registry is a cheek swab and a short health form. You are contacted only if you turn out to be a possible match for someone, and you can ask questions and decline before anything else happens.
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
- X-linked lymphoproliferative syndrome — NIH NCATS GARD, updated 2026-06
- Guidelines for hematopoietic stem cell transplantation for inborn errors of immunity — EBMT/ESID Inborn Errors Working Party, 2021
- EBMT Handbook, Chapter 90: Inborn Errors of Immunity — EBMT/Springer, 2024-04-11