Inherited metabolic disorders
Mucopolysaccharidosis type I, Hurler syndrome
Hurler syndrome is the severe form of mucopolysaccharidosis type I, caused by IDUA deficiency. Glycosaminoglycans accumulate and can affect development, bones, joints, heart, breathing, hearing and vision.
Other names and abbreviations
MPS IH · MPS I-H · Hurler syndrome · IDUA deficiency · MPS I · mucopolysaccharidosis · Severe mucopolysaccharidosis type I · Alpha-L-iduronidase deficiency, severe phenotype
Where transplant fits
Allogeneic transplantation is an established treatment for suitable young children with severe MPS I. Donor-derived cells provide enzyme and can slow neurologic decline, especially before substantial injury. A suitable unrelated donor or cord-blood graft can be an option.
Treatment depends on the exact diagnosis, disease stage, prior treatment and the person’s health. These categories are not estimates of donor demand.
Treatment at a glance
- Who it affects
- Severe MPS I becomes apparent in early childhood, sometimes following newborn screening or family testing.
- Other treatment options
- Laronidase enzyme replacement and multidisciplinary care address systemic disease and may be used around transplantation. Enzyme replacement has limited penetration into the brain.
- Cells used for transplantation
- When transplantation is appropriate, the graft contains blood-forming stem cells from a suitable donor. Bone marrow, peripheral blood or cord blood may be selected according to the condition and transplant protocol.
Why the details matter
Transplant does not eliminate every skeletal, eye or cardiac problem. Severe Hurler syndrome must be distinguished from attenuated MPS I when evaluating transplant benefit.
Questions to bring to your care team
What is the exact diagnosis or subtype? What is the goal of each treatment option? If transplant is being considered, why does it fit this situation, which cells would be used and what are the alternatives?
Sources and further reading
- Mucopolysaccharidosis Type I
GeneReviews, University of Washington / NCBI Bookshelf · Accessed 2026-09-05 - Inborn Errors of Metabolism and Osteopetrosis
EBMT Handbook · 2024-04-11
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