MAROTEAUX-LAMY SYNDROME
 
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    MAROTEAUX-LAMY SYNDROME

     

    DEFINITION:

    A lysosomal storage disorder characterized by the accummulation of acid mucopolysaccharide (dermatan sulfate) primarily in the peripheral tissues.

    EPIDEMIOLOGY:

    • incidence: ?
    • age of onset:
      • 2-3 years of age
    • risk factors:
      • familial - autosomal recessive
        • chrom.#: 5p11-q13
        • gene: arylsulfatase B (ARSB)
      • M = F

    PATHOGENESIS:

    1. Background

    • arylsulfatase B is a lysosomal enzyme which catalyzes the breakdown of dermatan sulfate (DS)
    • disease first described in 1963 by Maroteaux and is now classified as Mucopolysaccharidosis Type VI (MPS VI)

    2. Genetic Defect

    • genetic defect -> deficiency of arylsulfatase B activity -> incomplete degradation of dermatan sulfate -> accumulation of DS in the cells of the musculoskeletal system causing severe musculoskeletal changes
    • mild, moderate, and severe phenotypes exist

    CLINICAL FEATURES:

    1. CNS Manifestations

    1. Intelligence

    • normal

    2. Others

    • cervical spinal cord compression due to atlantoaxial subluxation or thickened dura -> cervical myelopathy -> leg weakness, paraplegia, paralysis
    • occasionally hydrocephalus with increased intracranial pressure

    2. Musculoskeletal Manifestations

    1. Facial Features

    • coarse facies
    • thick nostrils and lips
    • enlarged head at birth

    2. Skeletal Features

    • growth retardation with short trunk and neck
    • short stature (dwarfism)
    • pectus carinatum deformity (pigeon chest)
    • lumbar kyphosis and lordosis
    • decreased joint mobility - hips, knees, eibows -> may assume a crouched stance
    • hip dysplasia
    • genu valgum
    • carpal tunnel syndrome
    • flexion contraction of the fingers -> claw hand deformities

    3. Other Manifestations

    1. Respiratory

    • restrictive lung disease due to restrictive chest wall movement secondary to kyphoscoliosis

    2. Cardiovascular

    • aortic valvular dysfunction due to a stenotic calcified valve
    • mitral insufficiency

    3. Gastrointestinal

    • hepatomegaly/hepatosplenomegaly
    • inguinal and/or umbilical hernias

    4. Ophthalmologic

    • corneal opacities and/or clouding (slit lamp)
    • visual impairment

    5. ENT

    • conductive hearing loss

    INVESTIGATIONS:

    1. Diagnostic

    • deficiency of arylsulfatase B activity in leukocytes and cultured skin fibroblasts
    • prenatal
      • deficiency of enzyme activity in cultured chorionic villi or amniocytes

    2. Urine

    • 24 hour urine collection: elevated DS

    3. Imaging Studies

    1. Skeletal X-Rays

    1. Dystostosis Multiplex

    • large dolichocephalic skull
    • thickened calvarium
    • macrocephaly with an enlarged sella

    2. Vertebrae

    • ovoid deformity of the vertebral bodies
    • hook-shaped deformity or blunt anterior hypoplasia of the L1 and L2 vertebral bodies

    3. Hips

    • acetabular hypoplasia with small flared iliac wings

    4. Long Bones

    • epiphyseal dysplasia of the proximal femur
    • elongated femoral neck in a valgus position
    • irregular diaphyseal distension of tubular bones

    MANAGEMENT:

    1. Supportive

    • no treatment for underlying disease
    • multidisciplinary approach
      • Paediatrics, Neurology, Orthopedics, ENT, Ophthalmology,
      • OT, PT
      • genetic counselling

    2. Prognosis

    • life expectancy
      • 2nd to 3rd decade of heart failure
      • may die earlier of cardiac or neurologic complications
      • depends upon the severity of the disease
    • adult height: 110-140 cm

    INTERNET LINKS:

    The National MPS Society
     Mucopolysaccharidosis
     

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    Pediatric Database - MAROTEAUX-LAMY SYNDROME

     

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