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beta-mannosidosis

Tuesday 29 July 2008

Definition: Beta-mannosidosis is an autosomal recessive lysosomal storage disease of glycoprotein catabolism caused by a deficiency of lysosomal beta-mannosidase activity. Most patients have mental retardation.

Synopsis

- mild facial dysmorphism may occur
- deafness
- tortuosity of conjunctival vessels
- tortuosity of conjunctival vessels
- angiokeratoma
- cytoplasmic vacuolization
- thenar amyotrophy (rare)
- mental retardation
- speech impairment
- hypotonia
- seizures (rare)
- demyelinating peripheral neuropathy, progressive (rare)
- recurrent infections

LABORATORY

- Decreased beta-mannosidase activity in plasma, fibroblasts, and leukocytes
- Increased urinary disaccharides (mannosyl-N-acetylglucosamine)

Etiology

- beta-mannosidosis is caused by mutation in the gene encoding beta-mannosidase (MANBA) (MIM.609489).