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Mucopolysaccharidosis type VI
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Condition

Mucopolysaccharidosis type VI

Mucopolysaccharidosis type VI, also known as Maroteaux-Lamy syndrome, is a progressive condition that causes skeletal abnormalities and the enlargement or wasting away of various tissues and organs.

Overview

Mucopolysaccharidosis type VI (MPS VI) is a progressive condition where tissues and organs enlarge, become inflamed or scarred, and eventually waste away (atrophy). While individuals are typically asymptomatic at birth, signs often appear during early childhood. Unlike other types of mucopolysaccharidosis, MPS VI does not affect intelligence.

Symptoms

The features of MPS VI affect many bodily systems, including the skeletal, cardiac, and respiratory systems:

  • Skeletal: Large head (macrocephaly), hydrocephalus, coarse facial features, large tongue, short stature, and joint contractures.
  • Neurological/Musculoskeletal: Carpal tunnel syndrome and narrowing of the spinal canal in the neck.
  • Cardiac/Respiratory: Heart valve abnormalities and airway narrowing, which can lead to sleep apnea and frequent respiratory infections.
  • Other: Enlarged liver and spleen (hepatosplenomegaly), umbilical or inguinal hernias, cloudy eye covering (cornea), and hearing loss.

Causes

MPS VI is caused by mutations in the ARSB gene, which provides instructions for producing the enzyme arylsulfatase B. This enzyme is responsible for breaking down large sugar molecules called glycosaminoglycans (GAGs). When the enzyme is missing or non-functional, GAGs accumulate within lysosomes, the cell's recycling centers. This buildup is toxic to cells, triggering inflammation and cell death, which leads to the enlargement and eventual atrophy of tissues and organs.

Inheritance

This condition is inherited in an autosomal recessive pattern, meaning both copies of the gene in each cell must have mutations for the condition to occur. Parents of an affected individual each carry one copy of the mutated gene but typically do not show symptoms.

Frequently Asked Questions

Since MPS VI is autosomal recessive, each sibling of an affected child has a 25 % chance of being affected if both parents are carriers. Offer carrier testing to both parents using targeted ARSB mutation analysis. If both are confirmed carriers, discuss reproductive options: prenatal diagnosis via chorionic villus sampling or amniocentesis, pre‑implantation genetic testing for embryos (PGT‑M), or use of donor gametes. Genetic counseling is essential to explain recurrence risk and testing timelines.
Enzyme replacement therapy (ERT) with galsulfase (Naglazyme) is FDA‑approved. Weekly intravenous infusions can stabilize or improve joint range of motion, reduce liver/spleen size, and slow progression of cardiac valve thickening. Early initiation (ideally before irreversible organ damage) yields the best outcomes. Some patients may also be candidates for hematopoietic stem cell transplantation, though this is less common due to transplant‑related risks.
The first step is a quantitative assay of arylsulfatase B activity in leukocytes or dried blood spots; markedly reduced activity confirms the biochemical defect. Positive screening is followed by molecular genetic testing of the ARSB gene to identify pathogenic mutations. Baseline imaging includes skeletal X‑rays (to assess dysostosis multiplex), echocardiography (for valve disease), pulmonary function tests, and ophthalmologic examination for corneal clouding.
Regular cardiology follow‑up with echocardiogram every 12–24 months is recommended to track valve function and ventricular size. Pulmonary assessment includes annual spirometry, sleep studies for obstructive sleep apnea, and prompt treatment of upper airway infections. Airway clearance techniques, CPAP for sleep apnea, and timely surgical interventions (e.g., valve repair or tracheostomy) are employed based on severity.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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