PEDBASE.org - The Pediatric Database - Detailed information of GALACTOSIALIDOSIS

GALACTOSIALIDOSIS

DEFINITION:

A neurodegenerative disorder characterized by myoclonic seizures, tonic-clonic seizures, progressive neurologic dysfunction (dementia and ataxia), and macular cherry-red spots.

EPIDEMIOLOGY:

incidence: rare
age of onset:
- 2nd to 3rd decade
risk factors:
- familial - autosomal recessive
  - chrom.#: 20q13.1
  - gene: ?
- M = F
- racial - Japanese

PATHOGENESIS:

1. Background

one of the 5 major conditions that account for the majority of cases of "Progressive Myoclonus Epilepsies"
considered to be a lysosomal storage disease
may be considered a juvenile form of Sialidosis

2. Genetic Defect

genetic defect -> deficiency of a 32-kilodalton protein that is essential for the catalytic activity of alpha-N-acetyl-neuraminidase and normally protects beta-galactosidase from degradation -> relative deficiencies of both alpha-N-acetyl-neuraminidase and beta-galactosidase -> accumulation of sialyloligosaccharides and sialylglycopeptides in lymphocytes, fibroblasts, bone marrow cells, Kupffer cells (liver), Schwann cells, etc.

CLINICAL FEATURES:

1. Neurological Manifestations

1. Initial

1. Myoclonic Seizures

generalized affecting the extremities
triggered by voluntary movement, touch, sound, smoking, menstrual cycle
progressive -> nonambulatory

2. Macular Cherry-Red Spot

progressive loss of visual acuity
gradual loss of vision

2. Later

tonic-clonic seizures
ataxia
mental deterioration -> dementia
hearing loss

2. Others

coarse facies
angiokeratoma corporis diffusum

INVESTIGATIONS:

1. Imaging Studies

1. CT/MRI

generalized cerebral atrophy

2. Skeletal X-Rays

dysostosis multiplex

2. Pathology

1. Sialyloligosaccharides/Sialylglycopeptides

detected by light microscopy
periodic acid-Shiff-positive inclusions (vacuolations) within cells throughout the body
represents the lysosomal storage material

3. Urine

increased secretion of sialyloligosacchraides and sialylglycopeptides detected by thin-layer chromatography

4. Diagnostic

deficiency of alpha-N-acetylneuraminidase and beta-galactosidase activites in leukocytes or cultured skin fibroblasts
prenatal:
- deficiency of alpha-N-acetylneuraminidase and beta-galactosidase activities in cultured chorionic villi or amniocytes

MANAGEMENT:

1. Supportive

no treatment available for the disorder
multidisciplinary approach to ongoing problems
- Paediatrics, Neurology, Ortho, PT, OT, Ophthalmology
- myoclonic seizures difficult to control

Pediatric Database - GALACTOSIALIDOSIS

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