An 8-year-old boy is described with borderline cognitive impairment, cerebellar hypoplasia, a stroke-like episode, and venous thrombosis of the left leg after a period of immobilization. The pattern of multiple abnormalities in blood coagulation suggested carbohydrate-deficient glycoprotein syndrome type 1a. Isoelectric focusing of serum transferrin was abnormal. The activity of phosphomannomutase in leukocytes and fibroblasts was decreased. Mutation analysis of the PMM2 gene revealed the R141H/E151G genotype. These results confirm the presence of carbohydrate-deficient glycoprotein syndrome type 1a without severe psychomotor retardation.