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January 1977

Mannosidosis: New Clinical Presentation, Enzyme Studies, and Carbohydrate Analysis

Author Affiliations

From the Eunice Kennedy Shriver Center for Mental Retardation, Inc, at the Walter E. Fernald State School, Waltham, Mass (Drs Lott, Kolodny, Friedman, and Schnur); the Departments of Neurology (Drs Lott and Kolodny), Dermatology (Dr Mihm), and Pathology (Drs Dvorak and Dickersin), Massachusetts General Hospital, Boston; and the Tufts-New England School of Dental Medicine (Dr Nersasian).

Arch Neurol. 1977;34(1):45-51. doi:10.1001/archneur.1977.00500130065013

• Mannosidosis is a rare inborn error of metabolism characterized by deficiency of the lysosomal enzyme α-mannosidase and widespread storage of complex carbohydrate, which is enriched in mannose. Two affected unrelated males, aged 6 and 26 years, are reported. Both had a nonprogressive encephalopathy with moderately severe mental retardation. The older patient showed several unique features, including massive gingival hyperplasia associated with histiocytes containing large amounts of a material with the staining characteristics of glycoprotein. The best determinant of mannose storage proved to be the ratio of mannose to other carbohydrates in urinary polysaccharides. The enzyme deficiency in this disease is most convincingly demonstrated at pH values below 4.0. The ability of zinc to activate the mutant enzyme in vitro offers a possible mode of therapy for this disease. Retarded individuals with a Hurler-like appearance and gum hyperplasia of unknown cause should be screened for α-mannosidase deficiency.

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