Antenatal diagnosis in combination with elective termination of pregnancy has become an integral part of the approach to otherwise fatal, inherited disorders. Several of these disorders (termed sphingolipidoses) are characterized by deficient activity of a specific acid hydrolase and the concomitant accumulation of a complex molecule whose catabolism is normally associated with the disease-related acid hydrolase. These complex molecules are important structural components of cell membranes and under conditions of abnormal catabolism form aggregates within the cell, particularly within membrane-bound subcellular organelles. These organelles resemble lysosomes, which are, in fact, the major subcellular localization of the various acid hydrolases. Both …. © 1973, Massachusetts Medical Society. All rights reserved.