Mannosidosis
Etiology & Pathogenesis [1]Exists in two forms, alpha and beta, which are found in separate gene locations but have similar effects. Alpha-mannosidase is essential in the breakdown and recycling of the sugar mannose. The enzyme deficiency results in the mannose component collecting in the body’s cells, causing progressive damage. Key Symptom Images
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| Mild hepatosplenomegaly |
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Lumbar gibbus |
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Thick calvaria |
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Image Credits: Lumbar gibbus courtesy of Emil Kakkis, MD, PhD; www.medcyclopaedia.com. Thick calvaria courtesy of www.medcyclopaedia.com.
Clinical Description [1] and Progression/Prognosis Major manifestations relate to the storage of complex mannose sugars in the brain, bones, liver, and eyes. Symptoms of the most severe form may begin within the first months of life, with rapid progression of mental retardation, reduced hearing, liver and spleen enlargement, skeletal abnormalities, and coarse facial features. A milder form of the disorder involves early although mild-to-moderate mental retardation that may develop during childhood or adolescence. Inheritance pattern: autosomal recessive Incidence: 1 in 500,000 [2] Diagnosis: enzyme assay [3] Conditions with similar presentations: mucopolysaccharidoses [3] Management: no disease-specific treatment available Other medical care: symptom management
 Alpha-mannosidosis only: Vomiting Mild hepatosplenomegaly Alpha-mannosidosis: Large head Thick calvaria Low anterior hairline Coarse facial features Thick eyebrows Flat nose Large ears Macroglossia Widely spaced teeth Muscular hypotonia Lumbar gibbus Big hands and feet Dysostosis multiplex Bowed femurs Gingival hypertrophy Beta-mannosidosis: Coarse facial features Deafness Mild bone disease Back to categories Alpha-mannosidosis only: Lens opacities Prognathism Endocrine Alpha-mannosidosis only: Tall stature Alpha-mannosidosis only: Recurrent respiratory tract infections Immunologic Alpha-mannosidosis only: Immunoglobulin deficiency Hypogammaglobulinemia Antiplatelet antibodies Antineutrophil antibodies Low haptoglobin level Back to categories Alpha-mannosidosis: Mental retardation Beta-mannosidosis: Delayed speech development Hyperactivity Mental retardation Behavioral abnormalities Dermatologic beta-mannosidosis only: Genital angiokeratoma Back to categories
1. DL, Hauser SL, Longo DL, eds. Harrison’s Principles of Internal Medicine. 14th ed. New York: McGraw-Hill; 1998; p. 2175.
2. Meikle PJ, Hopwood JJ, Clague AE, Carey WF. Prevalence of Lysosomal Storage Disorders. JAMA. 1999; 281: 249-254.
3. Malm, Dag, Ph.D; Nilssen, Oivind, Ph.D. Alpha-Mannosidosis. www.genetests.org. Updated 3 December 2003. Accessed July 2004.
4. www.orpha.net//consor/cgi-bin/OC_Exp.php?Lng=GB&Expert=61. Accessed July 2004.
5. www.orpha.net//consor/cgi-bin/OC_Exp.php?Lng=GB&Expert=118 Accessed July 2004. |
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