Mucopolysaccharidosis type VI (also known as Maroteaux-Lamy syndrome) is a lysosomal storage disorder characterized by the deficiency of the arylsulfatase B enzyme. The clinical phenotype and severity of the condition varies according to the residual enzyme activity. Typical features include a short stature, shortened trunk, protruberant abdomen, flexed knee stance, arched back, corneal clouding, joint stiffness and contractures, and a waddling gait. Patients show Hurler-like dysmorphic facial features: microcephaly, prominent forehead and eyes, broad nose, low nasal bridge, thick lips, and hyperplastic gums with widely space teeth. Complications of the condition include obstructive airway, cardiac valvular problems, splenomegaly, hernias, and pneumonia. Unlike other MPS diseases, MPS VI is characterized by normal intellectual development.

Since the disease is the effect of deficient glycosaminoglycan (GAG) metabolism, elevated urinary GAG levels are an indication of its presence. Diagnosis is confirmed upon enzyme assays, specifically low arylsulfatase B activity in conjunction with normal activity of other lysosomal enzymes. The arylsulfatase B or N-acetylgalactosmaine 4-sulfatase is a major enzyme involved in the metabolism of gylcosaminoglycans. When tissues show deficiency of this enzyme, the GAG is unable to be metabolized and instead, accumulates within the lysosomes of most cell types, especially those in the connective tissue. These cells then begin to malfunction, leading to the characteristic clinical features noticed in MPS VI.

The condition is inherited in an autosomal recessive manner, since both alleles of the ARSB gene, which codes for the enzyme, need to be defective to produce the phenotypic effect.