Question 1

What is MPS?

Accepted Answer

Mucopolysaccharidoses (MPS) are a group of rare inherited disorders where the body cannot break down long chains of sugar molecules called glycosaminoglycans (GAGs). These accumulate in cells throughout the body - bones, joints, heart, brain - causing progressive damage. There are 7 main types (MPS I through VII), each caused by deficiency of a different enzyme. Common features: skeletal abnormalities, joint stiffness, short stature, coarse facial features, heart valve problems, and in some types, intellectual disability. Severity varies from severe forms incompatible with survival past childhood to attenuated forms compatible with long life but significant disabilities.

Question 2

What are the different types of MPS?

Accepted Answer

MPS I (Hurler, Hurler-Scheie, Scheie): Range from severe (Hurler - intellectual disability, early death without treatment) to mild (Scheie - normal intelligence, skeletal issues). MPS II (Hunter): Similar to Hurler but X-linked (only boys), ranges from severe to attenuated. MPS III (Sanfilippo): Primarily affects brain - severe intellectual disability, behavioral problems, relatively mild skeletal features. MPS IV (Morquio): Normal intelligence, severe skeletal dysplasia, short stature, spine and hip problems. MPS VI (Maroteaux-Lamy): Normal intelligence, severe skeletal disease, short stature, corneal clouding. MPS VII (Sly): Very rare, variable severity. Each type has different enzyme deficiency but overlapping features.

Question 3

Will my child be intellectually disabled?

Accepted Answer

Depends on MPS type. Normal intelligence: MPS IV (Morquio), MPS VI (Maroteaux-Lamy), MPS I Scheie (attenuated). Intellectual disability develops: MPS I Hurler (severe, if not transplanted early), MPS II Hunter (severe form), MPS III Sanfilippo (most severe cognitive impairment), MPS VII Sly (variable). If your child has MPS I Hurler and receives bone marrow transplant before age 2.5 years, cognitive decline may be prevented or minimized (this is why transplant is recommended). Enzyme replacement therapy (ERT) does NOT prevent intellectual disability because enzyme doesn't cross into brain.

Question 4

What is enzyme replacement therapy and does it cure MPS?

Accepted Answer

Enzyme replacement therapy (ERT) is weekly IV infusions of lab-made enzyme that your child's body cannot produce. Available for MPS I, II, IVA, VI, VII (NOT MPS III - enzyme can't reach brain). ERT does NOT cure MPS but slows progression: reduces GAG accumulation in organs, improves respiratory and cardiac function, may stabilize skeletal disease, improves endurance and quality of life. Limitations: doesn't reverse existing damage, doesn't cross blood-brain barrier (no cognitive benefit), requires lifelong weekly infusions, expensive (PBS-subsidized in Australia). Most effective when started early, before severe organ damage.

Question 5

Should my child have a bone marrow transplant?

Accepted Answer

Bone marrow transplant (hematopoietic stem cell transplant) is ONLY recommended for severe MPS I (Hurler syndrome) if diagnosed before age 2.5 years. Why? It provides continuous enzyme production (better than weekly ERT) AND may prevent intellectual disability (enzyme from donor cells can reach brain). Transplant is NOT standard treatment for other MPS types (risks outweigh benefits). It's a high-risk procedure: 10-20% mortality, graft-versus-host disease, 6+ months intensive care. But for severe MPS I diagnosed early, transplant offers best chance of preventing cognitive decline and may improve long-term outcomes.

Medical disclaimer

Mucopolysaccharidoses (MPS) in Children

Overview

What is Mucopolysaccharidoses (MPS) in Children?

What causes it?

Risk factors

You may be at higher risk if:

Prevention