Sialidosis - Type I (Cherry-Red-Spot-Myoclonus Syndrome)
Etiology and Pathogenesis
One of five conditions that account for the majority of cases of progressive myoclonus epilepsies. Enzyme deficiency results in accumulation of sialyloligosaccharides and sialylglycopeptides, affecting lymphocytes, fibroblasts, bone marrow cells, Kupffer cells (liver), and Schwann cells. Key Symptom Images
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Strabismus |
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Image Credits: Lens opacities courtesy of John A. Moran Eye Center, University of Utah.
Clinical Description and Progression/Prognosis
Neurodegenerative disorder characterized by myoclonic seizures, tonic-clonic seizures, progressive neurologic dysfunction (ataxia), and cherry-red macular spots. Type I, known as “cherry-rod-spot-myoclonus syndrome,” has an onset from 8 to 25 years and is distinguished by a lack of abnormal somatic features. Inheritance pattern: autosomal recessive Incidence: 1 in 4,222,000 live births (for types I and II together) [1] Diagnosis: Enzyme assay of sialidase activity in fresh tissue (ie fibroblasts, cultured amniotic fluid cells, or leukocytes.) [2] Conditions with similar presentations: I-Cell Disease (Mucolipidosis Type II) mucopolysaccharidosis Type IH; galactosialidosis. Management: no disease-specific treatment available Other medical care: symptom management
 Generalized myoclonus Tonic-clonic seizures Ataxia with gait disturbances Neuropathy Hyperreflexia Decreased deep tendon reflexes Initial: Cherry-red macular spots Progressive loss of visual acuity Later: Impaired color vision or night blindness Lens opacities Nystagmus Back to categories
1. Meikle PJ, Hopwood JJ, Clague AE, Carey WF. Prevalence of Lysosomal Storage Disorders. JAMA. 1999; 281: 249-254.
2. Thomas, George. “Disorders of Glycoprotein Degradation: -Mannosidosis, -Mannosidosis, Fucosidosis, and Sialidosis.” The Metabolic and Molecular Bases of Inherited Disease, 8th Edition Online. McGraw-Hill. http://genetics.accessmedicine.com/server-java/Arknoid/amed/mmbid/co_chapters/ch140/ch140_p01.html
Accessed September 2004. |
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