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At a glance

The three variants of Maroteaux-Lamy Syndrome (mucopolysaccharidosis [MPS] type VI) are severe, intermediate, and mild. The severe form of this condition is similar to the severe form of Hurler Syndrome, except for the preservation of intelligence in these patients. The clinical features include macrocephaly, coarse facial features, macroglossia, joint abnormalities, hearing loss, and short stature. Hepatosplenomegaly, cardiac anomalies, and restrictive pulmonary disease are commonly reported. The heart disease involves valvular dysfunctions. The airway can be compromised and difficult airway management during anesthesia must be expected. Corneal opacities are often present. Other features include numerous skeletal malformations such as stubby fingers, joint restrictions, claw hands, lumbar lordosis, and hip pain that occur after the age 3 or 4 years. As a matter of information, the administration of an enzyme replacement therapy has been successful in improving growth and joint movement. At a cost of $365,000 a year, Naglazyme is considered one of the world’s most expensive drugs!

Synonyms

Mucopolysaccharidosis Type VI; Arylsulfatase B Deficiency; N-Acetylgalactosamine-4-Sulfatase Deficiency; Polydystrophic Dwarfism; Pyknodysostosis of Maroteaux-Lamy.

History

This medical condition was first described by Maurice Emile Joseph Lamy (1895-1975) and Pierre Maroteaux (b. 1926), both French physicians, in 1963.

Incidence

The exact incidence and prevalence of Maroteaux- Lamy Syndrome remains unknown. It seems to affect males and females equally. Patients affected with the severe form of this disease usually die by early adulthood. One survey in British Columbia, Canada, reported a frequency estimated at 1:216,000 live births. The incidences of all types of MPSs have been reported between 1:25,000 and 1:500,000 depending on the type. The prevalence of all forms of MPS is estimated at 1:43,261 to 1,505,160 live births in the general population. However, the milder forms are misdiagnosed and often unrecognized which makes it difficult to determine the exact frequency in the general population.

Genetic inheritance

Autosomal recessive trait.

Pathophysiology

Deficiency of N-acetylglucosamine-4-sulfate sulfatase B leads to excessive accumulation of dermatan sulfate in the urine. It is a continuous storage disorder that leads to accumulation of dermatan sulfate in the skeleton, heart valves, spleen, liver, and cornea. The enzyme deficiency results in an inability to metabolize mucopolysaccharides.

Diagnosis

Phenotype. Dermatan sulfituria. There is a specific enzyme assay.

Clinical aspects

Resembles Hurler Syndrome, but is not usually associated with mental retardation. Patients have coarse facial features, short neck and trunk, skeletal abnormalities (hypoplasia of hip acetabula, flared iliac wings, hypoplasia of L1 to L2 vertebral bodies, and lumbar kyphosis), hernias, and corneal clouding. Sleep apnea syndrome is common. Mitral or aortic insufficiency may occur; heart failure is the most common cause of death (second or third decade). Hepatosplenomegaly.

Precautions before anesthesia

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