Deficiency of acid esterase activity in Wolman's disease.

esterase acting on fatty acid esters of p-nitrophenol, thereby substantiating the view that a single enzyme is responsible for these different activities. The acid esterase was resistant to the microsomal esterase inhibitor, E600, and showed broad specificity with respect to fatty acid chain length of the p-nitrophenyl esters. Other lysosomal hydrolase activities were increased non-specifically in liver from patients, thus providing further support for the classification of acid lipase deficiency as an inborn lysosomal disease. The highly sensitive leucocyte assay provides a convenient method for the diagnosis of clinical variants of Wolman's disease; it might therefore prove particularly useful in the early detection ofaffected infants, and also possibly in the differentiation of heterozygotes.