[Mannosidosis type II].

Four out of 7 siblings born of non-consanguineous parents have presented psychomotor retardation, macrocephaly and facial dysmorphism associated in 2 of them with thoraco-lumbar kyphosis and in one of them with recurrent pulmonary infections which had resulted in death. Chromatography of oligosaccharides displayed a characteristic mannosidosis profile. In addition, D-mannosidase activity was very low in leucocytes and fibroblasts. The father and mother showed no clinical abnormality and had no pathological urinary oligosaccharide excretion, but their leucocyte and fibroblast D-mannosidase activity was reduced. These cases give the authors an opportunity to describe the clinical and biochemical features of mannosidosis, which in its type II enables the patients to survive into adulthood, and to underline the value of D-mannosidase assays to detect subjects with this anomaly.