Oral zinc therapy in the treatment of alpha-mannosidosis

Human alpha-mannosidosis is a lysosomal storage disorder characterized by mental retardation, dysostosis multiplex, and hepatosplenomegaly. Deficiency of the enzyme leads to accumulation of mannose-rich glycoconjugates in tissues. Zinc sulphate has been shown to stimulate alpha-mannosidase activity in vitro. Oral zinc therapy was attempted on a 4-year-old boy with alpha-mannosidosis for 3 years. After almost 10 years of follow-up on and off zinc therapy, we must conclude that oral zinc does not substantially affect the clinical course of alpha-mannosidosis.