PEDBASE.org - The Pediatric Database -
Detailed information of SIALIDOSIS
SIALIDOSIS
DEFINITION:
A neurodegenerative disorder characterized by myoclonic seizures,
tonic-clonic seizures, progressive neurologic dysfunction (ataxia),
and macular cherry-red spots.
EPIDEMIOLOGY:
- incidence: rare
- age of onset:
- neonatal to adolescence (depends on the Type)
- risk factors:
- familial - autosomal recessive
- chrom.#: ?6p21.3
- gene: alpha-N-acetylneuraminidase
- M = F
PATHOGENESIS:
- one of the 5 major conditions that account for the majority
of cases of "Progressive Myoclonus Epilepsies"
- considered to be a lysosomal storage disease
- the difference between Sialidosis and Galactosialidosis is
that in the former there is a deficiency of alpha-N-acetylneuraminidase
while in the latter there is a combined deficiency of alpha-N-acetylneuraminidase
and beta-galactosidase
- alpha-N-acetylneuraminidases (there may be more than one
form) normally cleave terminal sialic acid residues of several
oligosaccharides, glycoproteins, and gangliosides
2. Genetic Defect
- genetic defect -> deficiency of alpha-N-acetylneuraminidase
-> accumulation of sialyloligosaccharides and
sialylglycopeptides in lymphocytes, fibroblasts, bone marrow
cells, Kupffer cells (liver), Schwann cells, etc.
- the difference between Types I and II Sialidosis is only the
Type II form is associated with abnormal somatic features -
coarse facies and dysostosis multiplex
TYPES:
CLINICAL FEATURES:
- 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 with gait disturbances
- mild peripheral neuropathy ("burning feet")
- usually not associated with dementia
- ocular manifestations:
- impaired colour vison or night blindness
- lens opacities
- nystagmus
- normal life spam-spam-spam
2. Type II - Neonatal Onset
- hydrops fetalis with:
- ascites
- hepatomegaly +/- splenomegaly
- inguinal hernia
- facial edema
- pericardial effusion
- corneal opacifications
- stillborn or death at an early age
3. Type II - Infantile Onset
- range from normal to minimal abnormalities to neonates
with ascites and hydrops fetalis
2. Later (end of 1st decade)
- mucopolysaccharidosis-like phenotypes
- visceromegaly
- mental retardation (but not progressive dementia)
- dysostosis multiplex
- progressive
- macular cherry-red spots
- myoclonic seizures
- ataxia
- death in the 2nd decade
INVESTIGATIONS:
- generalized cerebral atrophy
2. Skeletal X-Rays
- Type II - dysostosis multiplex
- Type II - Neonatal Form
- stippling of epiphyses
- periosteal cloaking
2. Pathology
- detected by light microscopy
- periodic acid-Schiff-positive inclusions (vacuolations)
within cells throughout the body
- represents the lysosomal storage material
3. Urine
- increased secretion of sialyloligosaccharides and
sialylglycopeptides detected by thin-layer chromatography
4. Diagnostic
- deficiency of alpha-N-acetylneuraminidase activity in
leukocytes or cultured fibroblasts
- prenatal:
- deficiency of alpha-N-acetylneuraminidase activity in
cultured chorionic villi or amniocytes
MANAGEMENT:
- no treatment available for the disease
- multidisciplinary approach to ongoing problems
- Paediatrics, Neurology, Ortho, PT, OT, Ophthalmology
- seizure control
- myoclonic seizures very difficult to control
|
Pediatric Database - SIALIDOSIS
Pediatric Organization - Pedbase [at] Gmail.com