FUCOSIDOSIS

 

FUCOSIDOSIS

 

DEFINITION:

A lysosomal storage disorder characterized by the accumulation of lipids (glycosphingolipids) in the CNS and peripheral tissues resulting in 2 clinical variants.

EPIDEMIOLOGY:

  • incidence: rare (about 60 cases reported)
  • age of onset:
    • infancy (Type I) -> 1-2 years of age (Type II)
  • risk factors:
    • familial - autosomal recessive
      • chrom.#: 1p34
      • gene: alpha-fucosidase
    • M = F
    • panethnic but increased frequency in Italians and Spanish-Americans

PATHOGENESIS:

1. Background

  • alpha-fucosidase is a homotetramer which catalyzes the removal of fucose residues from glycosphingolipids

2. Genetic Defect

  • genetic defect -> deficiency of alpha-fucosidase activity -> accumulation of fucose-containing glycosphingolipids and glyco-proteins in the CNS and peripheral tissues
    • lungs, heart, liver, pancreas, kidneys, cornea, skin, mucous-secreting glands, lymphocytes, peripheral nerves, spleen
    • major glycolipid accumulating is the H-antigen glycolipid
  • two clinical variants:
  • Type I - Infantile Form
  • Type II - Juvenile Form

CLINICAL FEATURES:

1. Type I (Infantile Form)

  • 60% of cases
  • early and rapid course with death around 5 years of age

1. CNS Manifestations

  • psychomotor retardation
    • begin to fall off milestones around the end of 1st year
    • weakness and hypotonia initially with eventual spastic quadriplegia
  • seizures
  • progressive mental retardation

2. Gastrointestinal Manifestations

  • hepatomegaly/hepatosplenomegaly
  • macroglossia
  • progressive impairment of gallbladder function

3. Musculoskeletal Manifestations

  • brachycephalic skull
  • frontal bossing
  • coarse facial features
  • growth retardation
  • lumbar kyphosis
  • joint contractures

4. Other Manifestations

1. Respiratory

  • chronic recurrent lung infections

2. Cardiovascular

  • cardiomegaly

3. Ophthalmologic

  • tortuous conjunctival vessels
  • slight corneal clouding
  • pigmentary retinopathy

4. Integument

  • thick skin
  • hyperhydrosis

2. Type II (Juvenile Form)

  • 40% of cases
  • later onset and slower course with survival into adulthood

1. CNS Manifestations

  • psychomotor retardation
    • later onset with slower progression
    • weakness and hypotonia initially with eventual spasticity and contractures

2. Musculoskeletal Manifestations

  • coarse facial features
  • growth retardation -> dwarfism

3. Integument Manifestations

1. Angiokeratomas

  • indistinguishable from those seen in Fabry Disease with similar distribution
  • onset about 3 years of age
  • small dark purple-blue telangiectasia
  • most dense between the umbilicus and knees with propensity for umbilicus and buttocks
  • occasionally occur in mouth

INVESTIGATIONS:

1. Diagnostic

  • deficiency of alpha-fucosidase activity in leukocytes or cultured skin fibroblasts (also samples from liver, lung, kidney, & brain)
  • prenatal
    • deficiency of alpha-fucosidase activity in cultured chorionic villi or amniocytes

2. Imaging Studies

1. Skeletal X-Rays

  • mild dysostosis multiplex
  • lumbar kyphosis
  • vertebrae - ovoid configuration with beaking of L2 and L3
  • acetabula deformed and sclerotic
  • widened shaft of long bones

2. CT/MRI

  • progressive leukodystrophy with demyelination and gliosis

3. Chest X-Ray

  • cardiomegaly

3. Urine

  • elevated fucose-rich oligosaccharides, sphingolipids, glycopeptides (about 22 glycopeptides) detected by thin-layer chrom-atography
  • no mucopolysaccharides

4. Pathology

1. Electron Microscopy

  • biopsy of the liver (hepatocytes, Kupffer cells), skin, conjunctiva shows vacuolization within the cells with some of the vacuoles empty and others rich in glycosphingolipids and glycoproteins
  • these cytoplasmic vacuoles are surrounded by a single mem-brane containing granular inclusions and lamellar bodies

5. Sweat Chloride

  • positive in the Infantile Form

MANAGEMENT:

1. Supportive

  • no treatment for underlying disorder
  • multidisciplinary approach
    • Paediatrics, Neurology, Ophthalmology, Orthopedics
    • genetic counselling

 

 

Pediatric Database - FUCOSIDOSIS

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