Inherited metabolic disorders
Mucopolysaccharidosis type I, Hurler syndrome
Also called: MPS IH · MPS I-H · Hurler syndrome · IDUA deficiency · MPS I · mucopolysaccharidosis · Severe mucopolysaccharidosis type I · Alpha-L-iduronidase deficiency, severe phenotype
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: the severe Hurler phenotype is apparent in the newborn or infant period in either sex. Evidence: U.S. NIH GARD synthesis (updated 2026); no markedly enriched population was identified.
- Treatments other than a transplant
- Laronidase enzyme replacement — approved — United States and European Union, 2003 — Treats somatic disease and is used peri-transplant, but does not adequately prevent central nervous system progression alone.
- If a transplant is used, the cells come from
- bone marrow: used; mobilized peripheral blood stem cells: rarely used in lysosomal-storage-disease HCT guidance; umbilical cord blood: frequently used and may be preferred to bone marrow; dominance: umbilical cord blood is the preferred source in the opened EBMT lysosomal-storage-disease guidance
- 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
Hurler-Scheie and Scheie phenotypes do not share the same routine HCT indication and should not be collapsed into this row.; ERT improves systemic disease but does not substitute for early HCT when preservation of cognition is the goal.
“An allogeneic transplant is the most common type of transplant for Hurler syndrome.”
It describes what teams consider in general. It cannot say what applies to any one person. Read the source.
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 metabolic disorders. They are genuinely different diseases with different treatments — the group name is not a diagnosis.
Where this came from
- Hurler syndrome — NIH NCATS GARD, updated 2026-06
- EBMT Handbook Table 91.2: Main characteristics of allo-HCT for Hurler, MLD, and X-ALD — EBMT/Springer, 2024-04-11
- Hurler syndrome and transplant — NMDP, accessed 2026-07-31