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.
This page is not written out in full yet
We have not written this condition out in full yet. What is on this page — how a donor fits in, who it affects, and the sources behind that — is researched and linked, but the plain-English explanation of the condition itself is still to come.
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.
“Successful outcomes have been reported with the use of matched-sib donors and marrow or umbilical cord blood from unrelated donors.”
It describes what teams consider in general. It cannot say what applies to any one person. Read the source.
Registries need people
Joining a registry is a cheek swab and a short health form. You are not matched to a condition — you are matched to a person, and it could be someone with any of the conditions in this library. 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
- X-Linked Lymphoproliferative Disease — GeneReviews / NCBI Bookshelf, accessed 2026-08-05