6-Phosphogluconate dehydrogenase deficiency in an Italian family

A rare case of hereditary erythrocyte enzymopathy, namely 6-phosphogluconate dehydrogenase (6PGD) deficiency, was found in an Italian family. The activity of the enzyme was reduced to 35% in the propositus and her mother, but was normal in the other three members of the family. The 6PGD deficiency was associated with a variable reticulocyte count and recurrent increased unconjugated bilirubinemia without anemia in the propositus, while no clinical or hematological symptoms were evident in her mother. Increased levels of erythrocyte pyruvate kinase (PK) activity and reduced glutathione (GSH) were observed, indicating a slight decrease in mean red blood cell (RBC) age and an activation of reducing systems. The episodic hemolytic events with jaundice observed in the propositus may be the result of a defective RBC ability to counteract conditions of marked oxidative stress. In this report the importance of 6PGD estimation for a proper analysis of glucose-6-phosphate dehydrogenase (G6PD) deficiency is also highlighted. In fact in the present study, the presence of 6PGD deficiency could be mistaken for a partial G6PD deficiency if the assay of G6PD activity was performed without correcting for 6PGD activity.

Congenital 6-phosphogluconate dehydrogenase (6PGD) deficiency associated with chronic hemolytic anemia in a Spanish family

Clinical and metabolic studies were performed in four members of a Spanish family with partial (50%) 6 phosphogluconate dehydrogenase (6PGD) deficiency. In all cases the activities of 6 phosphogluconolactone (6PGL) and glutathione reductase (GR) were normal, and the molecular characterization performed in the partially purified 6PGD from the propositus showed normal kinetic and electrophoretic patterns. Two females (the propositus and her sister) suffered from a well-compensated chronic nonspherocytic hemolytic anemia (CNSHA) and exhibited decreased RBC glutathione (GSH) stability with increased oxidative susceptibility, defined by enhanced malonyldialdehyde (MDA) generation "in vitro." The other two members of the family (the propositus's mother and brother) were clinically asymptomatic. In the propositus and her sister, RBC metabolism exhibited a markedly abnormal concentration of glycolytic intermediates, mainly characterized by striking increases in fructose 1,6 bisphosphate (50-fold), dihydroxiacetone-phosphate (20-fold) and glyceraldehyde 3-phosphate (tenfold). Although the precise mechanism of the hemolysis in the two patients is unknown, the enhanced oxidative threat observed in their RBCs may interfere in some way with the glycolytic pathway function, leading to a marked increase in certain metabolic intermediates located before the glyceraldehyde 3 phosphate dehydrogenase (GA3PD) step. Since it seems that GA3PD half-life is modulated by fluctuations of the cytosolic redox status, an "in situ" approach was simulated by using permeabilized RBCs. In these conditions, GA3PD activity was significantly lower in the propositus and her sister than in the asymptomatic members of the family and the simultaneous normal control.

Cord blood red-cell enzymes and reduced glutathione in Indian neonates, normal and with pathologic jaundice

Red-cell enzymes and reduced glutathione (GSH) were assayed on cord blood in 307 Indian neonates. On follow-up, 20 of them developed pathologic jaundice. Of these, six had red-cell enzyme/GSH deficiency, seven had associated non-enzymatic causes of jaundice, and in the remaining seven the cause could not be diagnosed. In 41 other neonates, there was enzyme/GSH deficiency without pathologic jaundice. The degree of enzyme deficiency had no relation with jaundice. Red-cell enzyme/GSH deficiency state in neonates was associated with pathologic jaundice more frequently (six of 47; 12.8%) than in the absence of such deficiency (14 of 260; 5.4%). None of the jaundiced patients had very high levels of bilirubin nor needed exchange blood transfusion. There was no reduction in haemoglobin level in the enzyme/GSH deficient group with jaundice in comparison with non-deficient jaundiced neonates or normal subjects. The incidence of red-cell enzyme/GSH deficiency appears to be high in Indian neonates; however, the majority of them do not precipitate pathologic jaundice.

[Glucose-6-phosphate dehydrogenase deficiency and other erythrocyte enzyme abnormalities]

Normal values of glucose-6-phosphate dehydrogenase (G6PD), 6-phosphogluconate dehydrogenase (6PGD), glutathione reductase (GR), glucosephosphate isomerase (GPI), pyruvate kinase (PK) and pyrimidine 5'-nucleotidase (P5N) have been determined in normocytes, reticulocytes, newborn cord erythrocytes, and leucocytes. Metabolic and clinical aspects of G6PD and the classification of its genetic variants are reviewed. Enzyme determinations and their variation in drug-induced haemolysis are critically presented. Extensive tables are published listing the drugs and compounds that can cause haemolysis in G6PD-deficient patients, as well as those preparations which may, probably, be administered safely. Clinical and biochemical data in patients with the inherited enzyme defects GR, GPI, PK, and P5N, as well as acquired deficiency of the last-mentioned in chronic lead intoxication, are reviewed in the light of our personal experience in this field.

Erythrocyte enzyme deficiencies assessed with a miniature centrifugal analyzer

Methods for assaying 16 erythrocyte enzymes have been adapted to the miniature centrifugal analyzer. Less than 15 micro L of whole blood is required for all 16 assays. Variation attributable to temporal effects, rotor effects, and random residual error is minor. Initial population studies of blood from adults and cord-blood samples suggest a CV of less than 12% for 12 of the 16 enzymes; thus it should be possible to identify the heterozygous deficient individual. Preliminary data suggest that three such individuals, with enzyme activity (adenylate kinase, pyruvate kinase, phosphoglycerate kinase) about half the expected, have been identified, as well as two individuals deficient in glucose-6-phosphate dehydrogenase.

Partial deficiency of red cell 6-phosphogluconate dehydrogenase: a family study

A family with partial deficiency of erythrocytic 6PGD is described. Biochemical and electrophoretic analysis suggest that the partial deficiency is due to a silent PGD0 allele. Chromosomal analysis and assay of closely linked markers do not reveal a grossly detectable deletion.

Genetic rescue of a lethal "null" activity allele of 6-phosphogluconate dehydrogenase in Drosophila melanogaster

While a null activity mutant allele of the structural gene for 6-phosphogluconate dehydrogenase in Drosophila melanogaster is lethal, a similar mutation for glucose-6-phosphate dehydrogenase is not. Double mutant combinations lacking both enzyme activities, obtained either by recombination or by mutagen treatment of a chromosome bearing the lethal allele, result in a restoration of viability. The indispensability of the pentose phosphate shunt in Drosophila appears to depend upon the specific position of the block within the pathway.

Combined G-6PD and 6-PGD deficiency in a Hindu boy

A case of drug-induced haemolytic anaemia due to G-6PD deficiency is documented because of the associated asymptomatic 6-PGD deficiency--a combination probably reported only once before. Our studies of the patient's family suggest that 6-PGD deficiency is inherited through a simple autosomal dominant gene.

Erythrocytic glutathione reductase deficiency in a hospital population in the United States

In the USA, erythrocytic glutathione reductase (GSSG-R) deficiency is significantly more common, and can be considerably more pronounced in hospitalized patients (118/3198) than in outpatients (37/1639) or in apparently healthy persons (12/849). Retrospective analysis of illnesses found in 118 inpatients with erythrocytic GSSG-R deficiency revealed a striking and previously unsuspected association of the enzyme deficiency with a variety of chemotherapeutically treated hematological or nonhematological malignancies (51/118 patients, 43.2%, or 51/170 diagnoses, 30.0%). The prevalence of erythrocytic GSSG-R deficiency also increased in malnutrition, liver disease, and sepsis. Drugs of the nitrosourea class, particularly BCNU [1, 3-bis(2-chloroethyl)-1-nitrosourea] are causally implicated in the association of GSSG-R deficiency with malignancies. Severe of complete GSSG-R deficiency may handicap host response to infections.

Hemoglobin E, an oxidatively unstable mutation

When bloods from 3,159 individuals from the United States, Iran, Ethiopia, and South Vietnam were examined for erythrocytic enzyme deficiencies with a new test utilizing the visible reduction of 2,6-dichlorophenolindophenol by glutathione, gross turbidity was observed in 81 samples. All were from Southeast Asia and 78 contained hemoglobin E. The precipitation rates of various hemoglogins in hemolysates incubated with dichlorophenolindophenol were: Hb EE greater than Hb AE greater than other hemoglobins (A, S, C, D, A2, F, O-Arabia, Rush). Hemoglobin E is an oxidatively unstable hemoglobin, possibly with weakened alpha 1 beta 1 contact; it may result in increased susceptibility to oxidative hemolysis and can be simply detected and differentiated from both Hb C and Hb O-Arabia.

Drug-induced haemolytic anemia

Drug administration causes 16 to 18 per cent of cases of acquired immune haemolytic anaemia. The pathogenesis of erythrocyte sensitisation by drug-related antibody with or without fixation of complement is variable and there is a relationship between the responsible drug, the mechanism of red cell sensitisation, clinical manifestations, and laboratory methods of diagnosis. Drugs such as phenacetin and quinidine form a complex with the antidrug antibody, and the immune complex attaches to red cells usually fixing complement and causing acute intravascular haemolysis. Other drugs (e.g. penicillins) when given in high doses coat normal red cells in vivo and some patients develop a high titre IgG antidrug antibody which reacts with the coated cells. Haemolytic anaemia may develop, with red cell destruction being primarily extravascular. Cephalosporins cause positive direct antiglobulin tests in a small percentage of patients either by the same mechanism as penicillins or by modification of the red cell membrane leading to non-immunological absorption of serum proteins. Haemolytic anaemia has been reported only rarely. A few drugs (notably alpha-methyldopa) cause the development of autoimmune haemolytic anaemia. A knowledge of clinical manifestations and laboratory aids to diagnosis are necessary to distinguish immunohaematological abnormalities caused by drugs fron other causes. Drugs may also cause haemolytic anaemia by nonimmunologic mechanisms as a result of oxidative denaturation of haemoglobin. Factors which make red cells particularly susceptible to the effects of oxidant drugs are intraerythrocytic metabolic abnormalities or the presence of unstable haemoglobins.