Activator protein deficient Gaucher's disease. A second patient with the newly identified lipid storage disorder.

A report is presented based on the biochemical and immunochemical studies of various tissues from a 15-year-old boy with a neuronopathic form of Gaucher's disease. Qualitative and quantitative lipid analyses revealed a storage of glucosylceramide. The striking feature was that, employing the usual assay methods, a normal activity of the lysosomal enzyme glucosylceramidase was revealed, despite massive lipid accumulation. Immunochemical assays of hepatic and splenic tissue extracts from this atypical Gaucher's patient disclosed the absence of A1 activator protein, which is necessary for the enzyme degradation of glucosylceramide in vivo. This is the second documented case of a patient presenting with glucosylceramide activator protein deficiency.