Combined Glucosephosphate Isomerase and Glucose-6-Phosphate Dehydrogenase Deficiency of the Erythrocytes: A New Haemolytic Syndrome

Summary. A new haemolytic syndrome associated with the combination of genetically determined glucosephosphate isomerase and glucose-6-phosphate dehydrogenase deficiency of the erythrocytes was demonstrated in a German family. The propositus (a male), homozygous for the glucosephosphate isomerase deficiency and hemizygous for the glucose-6-phosphate dehydrogenase deficiency, has suffered from a moderate chronic nonspherocytic haemolytic anaemia since early childhood with haemolytic crises during infections and after the ingestion of haemolytic drugs. The family members, heterozygous or hemizygous for both of the enzyme defects, are phenotypic normal individuals. From the biochemical data it is concluded that the glucose-6-phosphate dehydrogenase deficiency might partly protect the glucosephosphate isomerase-deficient cells of the propositus by supporting the accumulation of glucose-6-phosphate, thus potentiating the markedly decreased glucosephosphate isomerase activity. In this case the enzyme may operate nearer to substrate saturation than do cells with glucosephosphate isomerase deficiency only.