Mannosidosis: Clinical, Fine‐structural and Biochemical Findings in Three Cases

SUMMARY Three boys, 4, 5, and 10 years old, with psycho‐motor retardation, slightly gargoyle‐like faces and recurrent infections were found to have vacuolized lymphocytes in the blood and bone marrow as well as diffuse skeletal alterations. Electron microscopy of liver biopsy specimens revealed vacuoles, presumably representing enlarged lysosomes engorged with storage material. The liver. a‐mannosidase activity was somewhat low but not absent, while several other acid hydrolases in the liver had very high activities. The a‐mannosidase activity was low also in white blood cells but not in plasma or urine. The liver and urine contained very high amounts of mannose‐rich compounds. It is concluded that the patients suffer from man‐nosidosis.