Jada Bascom Foundation
All conditions

Inherited metabolic disorders

Late-infantile metachromatic leukodystrophy

Also called: LI-MLD · late-infantile MLD · ARSA deficiency · metachromatic leukodystrophy · MLD · Late-infantile arylsulfatase A deficiency · Early-onset metachromatic leukodystrophy, late-infantile form

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.

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: the late-infantile form usually begins in the second year of life and represents about 50–60% of MLD. Evidence: U.S. NIH GARD synthesis (updated 2026); no markedly enriched population was identified.
Treatments other than a transplant
Lenmeldy (atidarsagene autotemcel) — approved — United States, 2024 — For presymptomatic late-infantile and eligible early-juvenile disease.; Libmeldy (atidarsagene autotemcel) — approved — European Union, 2020 — For eligible presymptomatic late-infantile or early-juvenile disease and eligible early symptomatic early-juvenile disease.
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

Allogeneic HCT is generally not recommended for classic late-infantile MLD, whereas approved autologous HSC gene therapy is a standard option before symptoms.; This row excludes multiple-sulfatase deficiency and saposin-B deficiency unless the program explicitly groups them.

Written for transplant clinicians, not for patients. We quote it so you can see what the guidance actually says:
“LENMELDY is indicated for the treatment of children with pre-symptomatic late infantile (PSLI), pre-symptomatic early juvenile (PSEJ)”

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

Registries need people

An unrelated donor is not a usual part of treating this condition. Registering still matters, for the many conditions where it is.

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.

Find your registry

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