Mucopolysaccharidosis type 6

Mucopolysaccharidosis type 6 (MPS VI), also known as Maroteaux-Lamy syndrome, is a rare autosomal recessive lysosomal storage disorder caused by deficiency of the enzyme arylsulfatase B (N-acetylgalactosamine-4-sulfatase), encoded by the ARSB gene. This enzyme is essential for the breakdown of the glycosaminoglycan (GAG) dermatan sulfate. When the enzyme is deficient or absent, dermatan sulfate accumulates progressively in lysosomes throughout the body, leading to cellular damage and multi-organ dysfunction. MPS VI presents with a wide clinical spectrum ranging from rapidly progressing severe forms to more slowly progressing attenuated forms. Key features include skeletal abnormalities (dysostosis multiplex), short stature, joint stiffness and contractures, coarse facial features, corneal clouding, cardiac valve disease, hepatosplenomegaly, and upper airway obstruction. Importantly, unlike some other MPS types, cognitive function is typically preserved in MPS VI, although complications such as hydrocephalus, spinal cord compression, and hearing loss can occur. Cardiac involvement, particularly thickening and dysfunction of heart valves, is a major cause of morbidity. Pulmonary function may be compromised due to restrictive lung disease from skeletal deformities and airway obstruction. Enzyme replacement therapy (ERT) with galsulfase (Naglazyme) is the primary disease-specific treatment, approved for MPS VI. It has been shown to improve endurance and pulmonary function and reduce urinary GAG levels. Hematopoietic stem cell transplantation (HSCT) has also been used in some patients, particularly in severe cases diagnosed early, and may offer benefits for certain disease manifestations. Supportive care is multidisciplinary and includes orthopedic interventions, cardiac monitoring, ophthalmologic care, respiratory support, and physical therapy. Early diagnosis and treatment initiation are critical for optimizing outcomes.

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