How is Maroteaux-Lamy Syndrome diagnosed?

Maroteaux-Lamy syndrome, also known as Mucopolysaccharidosis type VI (MPS VI), is diagnosed through a combination of biochemical urine testing for glycosaminoglycans (GAGs), enzyme activity assays in blood or skin cells, and genetic sequencing of the ARSB gene. Because Maroteaux-Lamy syndrome is a progressive, multisystem disorder, early identification is critical for accessing life-altering enzyme replacement therapies.

How is the diagnostic process for Maroteaux-Lamy syndrome structured?

The journey toward a diagnosis of Maroteaux-Lamy syndrome often begins with a clinical suspicion based on physical features such as skeletal dysplasia, corneal clouding, or hepatosplenomegaly. Physicians typically follow a tiered approach to confirm the diagnosis, moving from screening to definitive molecular testing.

What specific tests confirm a diagnosis of Maroteaux-Lamy syndrome?

Confirmation requires objective laboratory evidence to differentiate the condition from other metabolic disorders. The diagnostic workup typically includes:

• Urinary GAG analysis: Elevated levels of dermatan sulfate in the urine act as a primary screening indicator.


• Arylsulfatase B (ARSB) enzyme assay: A blood or skin fibroblast sample is tested to measure the activity of the ARSB enzyme; extremely low or absent activity confirms Maroteaux-Lamy syndrome.


• Molecular Genetic Testing: Sequencing the ARSB gene identifies specific pathogenic variants, which is essential for genetic counseling and family planning.


• Imaging: Radiographic skeletal surveys often reveal dysostosis multiplex, a hallmark of Maroteaux-Lamy syndrome.

Which specialists should be involved in the diagnostic process?

Given the rarity of Maroteaux-Lamy syndrome, the diagnostic odyssey can be long and frustrating. Families often consult multiple specialists before receiving an accurate diagnosis. You should seek guidance from a metabolic specialist (clinical biochemical geneticist) or a pediatric geneticist, as they are best equipped to interpret the specific enzyme and genetic data required to confirm Maroteaux-Lamy syndrome.

How is Maroteaux-Lamy syndrome differentiated from other conditions?

Maroteaux-Lamy syndrome is often confused with other Mucopolysaccharidoses (such as Hurler syndrome or Hunter syndrome) due to overlapping skeletal and physical features. Unlike some other MPS disorders, patients with Maroteaux-Lamy syndrome typically maintain normal cognitive development, which is a key clinical differentiator during the differential diagnosis process.

Next steps

• Consult a metabolic specialist or geneticist at an academic medical center.


• Request a referral to a center specializing in lysosomal storage disorders.


• Connect with the 3 community members on DiseaseMaps.org who share lived experiences with this condition.


• Prepare a detailed medical history, including photos of physical changes over time, to assist your specialist.

Medical disclaimer: This information is for educational purposes only and does not constitute medical advice, diagnosis, or treatment; always seek the advice of your physician or other qualified health provider with any questions regarding a medical condition.

References

• Orphanet: Mucopolysaccharidosis type VI (Maroteaux-Lamy syndrome)


• NIH GARD: Mucopolysaccharidosis type VI


• OMIM: Mucopolysaccharidosis type VI (Entry #253200)


• National MPS Society: MPS VI Patient Resources