Beta-mannosidosis. Beta-mannosidase deficiency.
Incidence
It is an autosomal recessive disease. Eleven patients have been reported up to 1994.
Clinical Characteristics
Mental retardation, hearing loss and possible seizures occur without hepatomegaly, no facial dysmorphism, and no skeletal changes or leukocyte inclusions. The usual clinical characteristics of this disease are coarse facial features, tortuous conjunctival vessels and deafness. There is mild bone disease. There is delayed speech development, hyperactivity, mental retardation, and behavioral abnormalities. There is a genital angiokeratoma. Angiokeratomas and tortuosity of retinal vessels have been observed. Other signs have included aggressive behavior, severe epilepsy, spastic quadriplegia and peripheral neuropathy. There is excessive urinary excretion and tissue accumulation of oligosaccharides. The deficiency of beta-mannosidase can be demonstrated in leukocytes, cultured fibroblasts and in plasma. Laboratory shows beta-mannosidase deficiency, low heparin sulfamidase activity in cultured fibroblasts, disacchariduria, mannosyl(1-4)-N-acetylglucosaminuria and heparan sulfaturia.
Precipitants
no
Provocation Tests
no
Diagnostic Procedures
EB-W, EB-F. There is excessive urinary excretion and tissue accumulation of oligosaccharides. The deficiency of beta-mannosidase can be demonstrated in leukocytes, cultured fibroblasts and in plasma. Laboratory shows beta-mannosidase deficiency, low heparin sulfamidase activity in cultured fibroblasts, disacchariduria, mannosyl (1-4)-N-acetylglucosaminuria and heparan sulfaturia.