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Glucose-6-Phosphate Dehydrogenase Deficiency: Diagnosis, Clinical and Genetic Implications
... It is recalled that the concentration ratio of GSSG and GSH reflects little else than a steady 25 state, which overwhelmingly results from fast enzymatic processes utilizing, degrading or regenerating GSH. 26 Major conclusions: A biological GSSG/GSH redox potential, as calculated by the Nernst equation, is a deduced 27 electrochemical parameter based on direct measurements of GSH and GSSG that are often complicated by 28 poorly substantiated assumptions. It is considered irrelevant to the steering of any biological process. ...
... iii) The third and most convincing example is a metabolomic study causing hemolysis [26], but the utilization of GSH by GPx. ...
Background:
The term GSSG/GSH redox potential is frequently used to explain redox regulation and other biological processes.
Scope of review:
The relevance of the GSSG/GSH redox potential as driving force of biological processes is critically discussed. It is recalled that the concentration ratio of GSSG and GSH reflects little else than a steady state, which overwhelmingly results from fast enzymatic processes utilizing, degrading or regenerating GSH.
Major conclusions:
A biological GSSG/GSH redox potential, as calculated by the Nernst equation, is a deduced electrochemical parameter based on direct measurements of GSH and GSSG that are often complicated by poorly substantiated assumptions. It is considered irrelevant to the steering of any biological process. GSH-utilizing enzymes depend on the concentration of GSH, not on [GSH](2), as is predicted by the Nernst equation, and are typically not affected by GSSG. Regulatory processes involving oxidants and GSH are considered to make use of mechanistic principles known for thiol peroxidases which catalyze the oxidation of hydroperoxides by GSH by means of an enzyme substitution mechanism involving only bimolecular reaction steps.
General significance:
The negligibly small rate constants of related spontaneous reactions as compared with enzyme-catalyzed ones underscore the superiority of kinetic parameters over electrochemical or thermodynamic ones for an in-depth understanding of GSH-dependent biological phenomena. At best, the GSSG/GSH potential might be useful as an analytical tool to disclose disturbances in redox metabolism. This article is part of a Special Issue entitled Cellular Functions of Glutathione.
... Some people are born with a mutation of the Glucose 6 phosphate dehydrogenase gene. Most of these individuals are asymptomatic but may exhibit non-immune hemolytic anemia, even severe anemia in response to exposure to certain environmental triggers, most commonly, infection or exposure to certain foods like fava beans (favism), medications or chemicals [2]. This inherited deficiency causes neonatal hyperbilirubinemia and chronic hemolytic anemia. ...
Background: All humans have the Glucose 6 phosphate dehydrogenase gene. Some people are born with a mutation of the Glucose 6 phosphate dehydrogenase gene. Most of these individuals are asymptomatic but may exhibit non-immune hemolytic anemia, even severe anemia in response to exposure to certain environmental triggers, most commonly, infection or exposure to certain foods like fava beans (favism), medications or chemicals. G6PD deficiency is an X-linked disorder that primarily affects males. Heterozygous females do not usually develop severe hemolytic anemia due to G6PD deficiency. This study destined to reveal the prevalence of G6PD deficiency in south Gujarat population. Methods: This is a retrospective case study designed to assess the prevalence of G6PD deficiency in gujarat population, for patient requesting G6PD test at multiple collection center of Desai metropolis laboratory pvt ltd. between January 2022 to May 2023. Glucose-6-phosphate dehydrogenase deficiency analysis was done by Methylene dye blue test (Arkray MBK) – Qualitative method. All G6PD deficient patient confirmed by G6PD-quantitative (Kinetic method). Results: Total 9180 patients (5790 male and 3394 female) were included in this study. They were subsequently categorized into various subgroups and analysed properly. The incidence of G6PD deficiency in the selected sample frame of cases was 3.69 %. In which 4.11% of G6PD deficient cases belong to the male while the rest 2.98 % belong to the female. Conclusion: Therefore, to conclude whenever clinical and hematological findings raise the suspicion of glucose 6 phosphate dehydrogenase deficiency, the disorder should be confirmed by quantitative/quantitative measurement of red blood cell enzyme activity in both male and female. There is also need for a large screening programme, especially in malaria endemic zones.
... Some people are born with a mutation of the Glucose 6 phosphate dehydrogenase gene. Most of these individuals are asymptomatic but may exhibit non-immune hemolytic anemia, even severe anemia in response to exposure to certain environmental triggers, most commonly, infection or exposure to certain foods like fava beans (favism), medications or chemicals [10]. almost exclusively male, due to the X-linked recessive nature of inheritance, but female carriers can be clinically affected due to unfavorable lionization [11]. ...
... However, various factors can influence activity assay results. Mature erythrocytes have approximately 50 times less G6PD activity than reticulocytes in the same individual; thus, G6PD activity measurements taken in the setting of reticulocytosis can be artificially high in G6PD-deficient patients [32][33][34]. Although leukocytes usually contribute to a very small fraction of the measured G6PD activity, they could account for a substantial fraction in the setting of hyperleukocytosis (>100 × 10 3 cells/µL) and anemia, [35,36] and for these cases, it is recommended to use a buffy coat free method. ...
Phenotypic rather than genotypic tests remain the gold standard for diagnosing glucose-6-phosphate dehydrogenase (G6PD) deficiency. However, with increasing use of genomic arrays and whole exome or genome sequencing, G6PD genetic data are increasingly available. We examined the utility of G6PD genetic data in patients with hematologic malignancies and the association of G6PD genotype and phenotype with rasburicase-induced methemoglobinemia. We analyzed G6PD activity for 990 patients. Genotype data were available from the Affymetrix DMET array (n = 379), whole exome sequencing (n = 374), and/or the Illumina exome array (n = 634) for 645 patients. Medical records of 341 patients with methemoglobin measures were assessed for the administration of rasburicase. We observed 5 non-synonymous SNPs, 4 of which were known to be associated with deficient G6PD activity (WHO Class I-III). Genotyping 367 males resulted in a positive predictive value of 81.8% (47.8-96.8%), and two males with a Class I-III allele having normal activity both received a red blood cell transfusion prior to the activity assay. However, genotyping males had only 39.1% (20.5-61.2%) sensitivity. Two of the 12 heterozygous females had deficient G6PD activity. Rasburicase-induced methemoglobinemia occurred in 6 patients, 5 of whom had at least one Class I-III allele, despite 2 of these having normal G6PD activity. We conclude that although an apparent nondeficient genotype does not necessarily imply a normal phenotype, a deficient genotype result indicates a deficient phenotype in those without transfusions, and may be a useful adjuct to phenotype to prevent adverse drug reactions.
... Si las muestras no pudieron procesarse en las dos primeras horas, se almacenaron a -20 °C hasta su posterior análisis (3-4 días más tarde). En ambos estudios la actividad de G6PD se midió con la prueba cuantitativa (método normalizado de Beutler para valoración de la G6PD en hemolizados) 22,32 . La medición cuantitativa fue ejecutada por uno de los investigadores y se hizo en dos espectrofotómetros diferentes, calibrados, previamente comprobada su concordancia para la medición. ...
INTRODUCTION: Glucose-6-phosphate dehydrogenase (G6PD) deficiency in Latin America has not been fully studied and in Colombia only three outdated publications are known. Recent information on the prevalence of G6PD deficiency is required now, because the recommended treatment of vivax malaria requires higher daily or total doses of primaquine. OBJECTIVE: To measure the prevalence of G6PD in a healthy male population and in a Plasmodium vivax infected population in Turbo (Urabá, Antioquia Department, Colombia). METHOD: Prevalence survey to evaluate G6PD in two populations of Turbo (Antioquia): healthy male; male and female with vivax malaria. The work was carried out on population samples selected using statistical and epidemiological criteria. Enzyme activity was measured using Beutler's normalized method to evaluate G6PD after hemolysis. RESULTS: For the healthy male group (n = 508), and with a 95% confidence interval (IC95%), the mean values were between 4.15 and 4.51 IU/g hemoglobin; 14.8% exhibited values below "normal", i.e. < 2.29 IU/g hemoglobin (G6PD prevalence). Among malaria-infected men (n = 206) IC95% ranged from 3.81 to 4.16, and among malaria infected women, it ranged from 3.86 to 4.20 IU/g of hemoglobin. The mean values observed in males (healthy vs. infected) were statistically different (p = 0.028). Only 9.5% (13/137) of the infected individuals, had G6PD deficiency and this occurred only within the male group. CONCLUSIONS: G6PD is relatively high among healthy people (14.8%) and in the P. vivax infected (9.5%) male population of Turbo.
... 1. Malaria exclusivamente por P. vivax según el exa- men de gota gruesa; 2. No tener malaria grave (com- plicada) según la OMS; 1 3. Tener parasitemia de 1.000 o más parásitos/μL; 4. Ser menor de 18 años; 5. No es- tar en embarazo según una prueba inmunológica en tirilla; 6. Tener actividad normal de glucosa 6-fosfato deshidrogenasa (G6PD), medida según la técnica cuan- titativa (método normalizado de Beutler para valora- ción de la G6PD en hemolizados); 19,20 7. Aceptar la par- ticipación en el estudio y firmar el consentimiento informado. ...
RESUMEN Introducción: se ha evaluado poco en el mundo la eficacia del tratamiento con cloroquina-primaquina para el ataque agudo y, sobre todo, para las recurrencias del paludismo vivax en niños; esos estudios en América Latina son muy escasos y casi inexistentes en Colombia. Objetivo: evaluar la eficacia de dos dosificaciones de primaquina en menores de 18 años. Materiales y métodos: estudio clínico controlado, no enmascarado, con asignación aleatoria del tratamiento. Se evaluaron dos grupos según la dosis de primaquina: 0,50 mg/kg/día por 7 días (0,50-7) frente a 1,17 mg/kg/día por 3 días (1,17-3). Resultados: A. Curación del ataque agudo: eficacia del 100% en los dos grupos; B. Prevención de las recurrencias durante 120 días: ocurrieron recurrencias en 68,4% de los niños tratados con el esquema 1,17-3, y en 34,2% de los que recibieron el régimen 0,50-7. Conclusiones: 1. La proporción de recurrencias a los 120 días en niños tratados con el esquema 0,50-7 (34,2%) fue significativamente menor que la de los niños que recibieron el régimen 1,17-3 (68,4%). 2. El tiempo de administración de una misma dosis total de primaquina influye en su eficacia contra las recurrencias: a menos días, menor eficacia.
... In some regions where malaria is endemic, glucose-6-phosphate dehydrogenase (G6PD) deficiency is a common trait. 7 Therefore, administration of the full 14-day course of PQ to G6PD-deficient persons is contraindicated because of the risk of severe hemolysis. 8 To overcome this problem, some governments have adopted a truncated five-day course of PQ for P. vivax malaria because this reduces the risk of hemolysis to negligible levels. ...
Plasmodium vivax malaria is an important cause of morbidity in Central and South America. In Colombia, this is the most prevalent malaria infection, representing 75% of the reported cases. To define the efficacy of the chloroquine and primaquine regimen to eliminate hypnozoites and prevent relapses, we conducted a random controlled clinical trial of three primaquine regimens in an open-label study. We evaluated the anti-relapse efficacy of total primaquine doses of 45, 105, and 210 mg administered at a dosage of 15 mg/day in 210 adults with P. vivax infection from the northwestern region of Colombia. Cure rates for blood-stage P. vivax malaria by day 28 of follow-up were 100% in all groups. Post-treatment reappearance of parasitemia during the six months of follow-up was 45%, 36.6% and 17.6%, respectively, for each group. When compared with other groups, administration of 210 mg was a significant protection factor for reappearance of parasitemia in a malaria-endemic area.
Objective:
To determine the efficacy of chloroquine monotherapy in Colombian pregnant women with acute uncomplicated malaria vivax (GMV).
Methods:
Prospective cohort study in pregnant women who presented of their own accord between February 1, 2015 and December 31, 2017 to malaria or prenatal care centers in two Colombian towns and in whom the diagnosis of Plasmodium vivax was confirmed by means of blood spot test and and quantitative polymerase chain reaction (qPCR). Measured variables included sociodemographics, therapeutic failure (TF) and serious adverse events at 28 days and frequency of recurrence-relap (RR) over a follow-up period of 120 days. The WHO protocol was applied for the assessment of monotherapy with cloroquine (m-CQ) efficacy.
Results:
Overall, 47 pregnant women were identified. During the 28-day follow-up period there were no losses, and there were two cases of TP (4.2%=2/47). Of the 45 women followed between 29 and 120 days, 11 were lost (24.4%=11/45) and there were 13 cases of RR, with an RR frequency ranging between 29 and 53 % depending on the type of analysis.
Conclusions:
Chloroquine is still highly effective as a cure of acute malaria vivax attack in GM in Colombia, and continues to be a good option for the treatment of acute phase GM. The RR frequency is high. Studies are required that evaluate therapeutic alternatives in MG. There is a pressing need for medications and/or procedures that can help reduce this very high risk.
Recent studies have highlighted the imperatives of including diverse and under-represented individuals in human genomics research and the striking gaps in attaining that inclusion. With its multidecade experience in supporting research and policy efforts in human genomics, the National Human Genome Research Institute is committed to establishing foundational approaches to study the role of genomic variation in health and disease that include diverse populations. Large-scale efforts to understand biology and health have yielded key scientific findings, lessons and recommendations on how to increase diversity in genomic research studies and the genomic research workforce. Increased attention to diversity will increase the accuracy, utility and acceptability of using genomic information for clinical care.
During the past few years many of the enzymes catalysing the reactions of the Embden-Meyerhof glycolytic pathway and the pentose—phosphate cycle have been demonstrated to occur in multiple forms. The former are, of course, of major interest in connection with the investigation of the mechanism of action of insulin, but at the present time it must be admitted that many of our conclusions are hypothetical. The isoenzymes of the pentose-phosphate cycle are of great importance in the study of hereditary anaemias, both from the diagnostic and genetic points of view. The principal enzymes concerned are shown in the diagram of both pathways illustrated in Fig. 18.
During the past few years many of the enzymes catalysing the reactions of the Embden-Meyerhof glycolytic pathway and the pentosephosphate cycle have been demonstrated to occur in multiple forms. The former are, of course, of major interest in connection with the investigation of the mechanism of action of insulin, but at the present time it must be admitted that many of our conclusions are hypothetical. The isoenzymes of the pentose-phosphate cycle are of great importance in the study of hereditary anaemias, both from the diagnostic and genetic points of view. The principal enzymes concerned are shown in the diagram of both pathways illustrated in Fig. 18.
The effect of pre-treatment with an alcoholic extract of Picrorhiza kurroa, a herbal drug, on D-galactosamine-induced hepatitis in rats was investigated with respect to the activities of serum marker enzymes, glycolytic enzymes, gluconeogenic enzymes, glucose-6-phosphate dehydrogenase, and membrane-bound ATPases and the levels of lipid peroxides and hepatic thiols. Prior oral treatment with P. kurroa extract significantly prevented the D-galactosamine-induced increases in the activities of serum marker enzymes, glycolytic enzymes, glycogen phosphorylase, and glucose-6-phosphate dehydrogenase and the decreases in the activities of key gluconeogenic enzymes and membrane-bound ATPases in the liver. The extract also exerted an antioxidant effect against D-galactosamine-induced hepatitis by blocking the induction of lipid peroxidation and by preventing the depletion of hepatic thiols. The present findings confirm that P. kurroa is hepatoprotective in experimentally induced hepatitis in rats.
Introduction: Worldwide, the efficacy of cloroquine-primaquine for treating acute Plasmodium vivax malarious attacks has not been thoroughly evaluated. In Latin America such studies are scarce, and in Colombia, almost nonexisting. Objective: To assess the efficacy of two regimens for administration of primaquine in children aged less than 18 years. Methodology: A clinical, controlled, unmasked study was carried out, with randomized administration of two primaquine regimens, namely: 0.50 mg/kg/day for 7 days (0.50-7) vs. 1.17 mg/kg/day for 3 days (1.17-3). Results: A. Healing of the acute attack: efficacy was 100% in both groups. B. Prevention of recurrences during 120 days: recurrences occurred in 68.4% of children treated with the 1.17-3 regimen, and in 34.2% of those receiving the 0.5-7 one. Conclusions: 1. Proportion of recurrences during the 120 days follow-up was significantly lower (34.2%) in children receiving the 0.50-7 regimen than in those treated with the 1.17-3 one (68.4%). The length of administration of the same total dose of primaquine influenced its efficacy against recurrences: shorter periods of administration were associated with lesser efficacy.
6,366 Afro-American infants were screened for G6PD activity. 379 males (11.4%) and 77 females (2.5%) were deficient. Confirmation was made by a standard spectrophotometric assay. The results for the male infants in this study are comparable to those found in other studies which accurately establish the deficient male.Copyright © 1980 S. Karger AG, Basel
The authors study in vitro the transformation into aldosterone of two types of 18 hydroxycorticosterones: synthetic 18 hydroxycorticosterone and a so called «endogenous 18 hydroxycorticosterone obtained through a specific experimental procedure. The synthetic 18 hydroxycorticosterone is transformed into aldosterone with 1,5 to 2 per cent efficiency (in agreement with the litterature) whereas the «endogenous 18 hydroxycorticosterone is totally unable of undergoing such a transformation. However, under rather drastic physicochemical treatments, this «endogenous 18 hydroxycorticosterone can partially recover some activity. The total inactivity of «endogenous 18 hydroxycorticosterone, either intra or extra mitochondrial, in the incubation medium, is not due to experimental conditions and is not modified by a cytoplasmic factor. It looks as if only the 18 hydroxycorticosterone «transiting between 18 hydroxylation and 18 dehydrogenase could be transformed into aldosterone. The different capacity for 18 hydroxycorticosterone to act as a precursor for aldosterone synthesis is discussed, not as an experimental artefact but rather as a physiological phenomenon, the meaning of which remains to be investigated.
The present study was undertaken on the hypothesis that methaemoglobin production and haemolytic anaemia following dapsone administration could be ascribed to an impairment of glucose-6-phosphate dehydrogenase-enzymatic activity. Analysis of the kinetic parameters of the G-6-PD (Vmax and KM) was performed in ten patients, normal with respect to G-6-PD, suffering from various dermatoses. It was concluded that haemolytic anaemia after dapsone therapy is not due to a functional impairment of the enzyme. The close relationship between dapsone dosage, methaemoglobin production and anaemia make reasonable the hypothesis that a toxic dapsone derivative (DDS-NHOH) could be responsible for the methaemoglobin formation and the haemolytic anaemia.
The authors study in vitro the conversion of 18 hydroxycorticosterone into aldosterone in duck adrenal subcellular fractions. The enzymatic nature of this conversion is studied by classical enzymologic tests. All results are in favor of an enzymatic conversion and this enzyme is strictly located in the mitochondrial fraction. Results concerning this localisation are expressed as specific activity and relative specific activity. Preliminary results on further experimental data point out that this conversion depends on the energetic state of mitochondria. Complete electron transfer blokage inhibits this transformation whereas respiratory chain blokage with a NADPH generating system and ATP supplementation does not seem to produce any inhibition. Oligomycine and guanidine stimulation suggest that ATP or its precursors may be involved in this reaction.
Selecting suitable anti-malarial treatment represents one of the best tools for reducing morbidity and mortality caused by this disease. Sexual and asexual parasite dynamics were thus evaluated in patients involved in antimalarial drug efficacy studies by using combined treatment with and without artemisinin derivatives for treating uncomplicated acute Plasmodium falciparum malaria in Antioquia, Colombia. All treatment doses were supervised and administered according to patients' weight; sexual and asexual parasitemia were evaluated during 28- or 42-days follow-up in 468 patients. Artemisinin-based combination therapy showed greater parasiticidal ability, showing a mean asexual parasitemia survival rate of one day and mean gametocyte survival rate of 1-2 days. Sexual and asexual parasitemias were eliminated more quickly and effectively in the group receiving artemisinin-based combination therapy. Adding 45 mg of primaquine to treatment with artesunate and mefloquine reduced gametocyte and asexual parasite survival by one day.
Primaquine (PQ) is recommended to prevent relapses in patients with Plasmodium vivax malaria infection. However, treatment with PQ causes methemoglobinemia. In this study, we measured the methemoglobin (MetHB) levels in three groups of subjects who received PQ treatment at 0.58, 0.83, or 1.17 mg/kg/d. A total of 112 subjects were studied. MetHB levels were detected at > or = 4% in 46-50% 1 day after PQ treatment in all three groups and 4-9% of subjects had MetHB levels > or = 4% 15 days after treatment. Only subjects receiving the highest doses of PQ had mild and brief adverse events, and 17% of them were associated with treatment. We conclude that when PQ is administered under certain conditions (i.e., normal glucose-6-phosphate dehydrogenase activity, in non-pregnant subjects and with a light meal), daily doses as high as 1.17 mg/kg do not represent a serious risk of high MetHB levels to patients.
Two improved methods for determination of erythrocyte glucose 6 phosphate dehydrogenase activity are described. One method is an 'enzyme linked' procedure in which an excess of 6 phosphogluconate dehydrogenase is used to produce 2 moles of NADPH for each mole of glucose 6 phosphate oxidized. In the other method 2,3 diphosphoglycerate is used to inhibit the variable contribution of endogenous 6 phosphogluconate dehydrogenase to glucose 6 phosphate dehydrogenase activity in erythrocyte lysates. These assays require 100 μl of blood and are performed on a centrifugal analyzer in a final reaction volume of 410 μl at 37 °C. NADPH formation is monitored at 340 nm. Hemoglobin is measured as oxyhemoglobin in the same reaction mixture used to determine enzyme activity by changing the wavelength to 550 nm. Results are expressed as international units of glucose 6 phosphate dehydrogenase activity per gram of hemoglobin. The coefficient of correlation between 'enzyme linked' assay and 'standard assay' was .992, the slope of the regression line was 1.07, and the intercept was at -0.76. When results of the 'enzyme linked' assay were compared to those of the 'nonlinked' assay with added 2,3 diphosphoglycerate, the slope of the regression line was .994, the intercept 0.109, and the correlation coefficient .994.
The present study was undertaken on the hypothesis that methaemoglobin production and haemolytic anaemia following dapsone administration could be ascribed to an impairment of glucose-6-phosphate dehydrogenase-enzymatic activity. Analysis of the kinetic parameters of the G-6-PD (Vmax and KM) was performed in ten patients, normal with respect to G-6-PD, suffering from various dermatoses. It was concluded that haemolytic anaemia after dapsone therapy is not due to a functional impairment of the enzyme. The close relationship between dapsone dosage, methaemoglobin production and anaemia make reasonable the hypothesis that a toxic dapsone derivative (DDS-NHOH) could be responsible for the methaemoglobin formation and the haemolytic anaemia.
S ummary
Hydrogen peroxide in micromolar concentrations can induce shape change in human blood platelets, and can modify the aggregation and release reaction of these cells as induced by ADP or thrombin. In larger (millimolar) concentrations, H 2 O 2 produces fusion of platelets with distortions in platelet morphology unlike those normally caused by aggregating agents. The production of H 2 O 2 in vivo by granulocytes or other cells could influence the processes of haemostasis or thrombosis.
Mediterranean spotted fever with haemolysis is reported in a glucose-6-phosphate dehydrogenase deficient Algerian man. The clinical course was unusually severe for a 27-year-old patient. The authors suspect G6PD deficiency to be a cause of enhanced severity in Mediterranean spotted fever as well as in other rickettsioses.
Deficiency of the erythrocyte enzyme, glucose-6-phosphate dehydrogenase [EC 1.1.1.49, GPD] is associated with hemolysis after exposure to oxidative drugs, ingestion of the fava bean, or infection. Episodes of hemolysis may be prevented by avoiding ingestion of substances toxic to erythrocytes with GPD deficiency. We describe here an automated fluorometric method suitable for screening for erythrocyte GPD deficiency. Anticoagulated whole blood is examined. Reliable results are obtained for hemoglobin concentrations ranging from 7-17 g/100 ml.
A simple visual test has been developed to detect and distinguish erythrocytic glucose-6-phosphate dehydrogenase (G6PD), 6-phosphogluconic dehydrogenase (6PGD), and glutathione reductase (GSSG-R) deficiencies either singly or in combination. The test is based on the nonenzymatic reduction of 2, 6, dichlorophenolindophenol by reduced glutathione which is generated from GSSG by GSSG-R if this enzyme is active and provided with NADPH either via G6PD or via 6PGD. Packed or sedimented erythrocytes are hemolyzed and the hemolysate is distributed and incubated into 2 tubes whose colors are observed. Initial standardization was achieved by using erythrocytes from individuals known to have normal or low G6PD, 6PGD, and GSSG-R activities. Diagnostic specificity was established and compared with that of cyanmethemoglobin elution. Normal erythrocytes require both NADPH generating steps of the pentose phosphate pathway for maximal redox-stimulated methemoglobin reduction; intermediate G6PD deficiency and complete 6PGD deficiency are indistinguishable by tests based on methemoglobin reduction.
An 11-year-o'.d Negro boy with a history of neonatal jaundice requiring exchange transfusion had a severe hemolytic episode at 8 years of age. A diagnosis of nonspherocytic congenital hemolytic anemia due to G-6-PD deficiency was made at that time. The red cells of the patient contained a level of G-6-PD activity approximating 14 per cent of normal. The residual enzyme was partially purified and characterized. It proved to be electrophoretically rapid. The Michaelis constant (Km) for G-6-P was diminished and that for NADP increased. The enzyme had greatly increased utilization of deamino-NADP and slightly increased utilization of 2-deoxyglucose-6-phosphate. The pH optimum curve was slightly bimodal. Like most other G-6-PD variants associated with congenital nonspherocytic hemolytic anemia, the enzyme was thermally labile. This enzyme represents a new deficent variant, G-6-PD Charleston. The patient continues to have chronic severe hemolysis. Two brothers presumably died of the same enzyme deficiency. The erythrocytes of two living brothers contain G-6-PD A-, The mother is heterozygous for the two variants.
The isozyme patterns of d-glucose-6-phosphate:NADP+ 1-oxidoreductase, EC 1.1.1.49 (glucose-6-phosphate dehydrogenase or Glc-6-P dehydrogenase) in blood and bone marrow cell lysates, and in homogenates from other human tissues were determined by the application of polyacrylamide gel disc electrophoresis.Nucleated blood cells, including bone marrow cells, and spleen homogenates exhibited the presence of five enzymatic bands (Bands I, II, III, IV, V). Liver homogenates showed four bands (Bands II, III, IV, V), lymph nodes showed three (Bands I, II, V) and brain homogenates exhibited two (Bands I, II) bands.In all hematopoietic cells examined, Bands I and II were found be specific for Glc-6-P dehydrogenase while Bands III, IV and V seem to be due to hexose-6-phosphate dehydrogenase activity.No differences were found in the Glc-6-P dehydrogenase isozyme pattern in samples of leukocytes, platelets or bone marrow from healthy subjects and from patients suffering from Glc-6-P dehydrogenase deficiency.
Punch autografting of the scalp is the cosmetic surgery of choice for ordinary patterned baldness, posttraumatic permanent hair loss, localized congenital absence of hair and a variety of pathologic cicatricial, dystrophic and atrophic alopecias.
The toxic effects of orally administered lapachol were studied in rodents, dogs, and monkeys. The single dose, combined sex, oral LD50 was 0.621 g/kg in mice and greater than 2.4 g/kg in albino rats. The male and female mice LD50 values were 0.487 and 0.792 g/kg, respectively. Beagle dogs were given daily oral doses of 0.25, 0.50, 1.0 or 2.0 g/kg 6 days a week for a total of 24 doses without lethal effect. Cynomolgus monkeys were treated on the same schedule and received doses of 0.0625, 0.125, 0.25, 0.5, or 1.0 g/kg/day. Death occurred in monkeys after six doses of 0.5 g/kg/day and after five doses of 1.0 g/kg/day. Signs of toxicosis in both dogs and monkeys included moderate to severe anemia, reticulocytosis, normoblastosis, pallor of mucous membranes, bilirubinuria, and proteinuria. Additionally, transient thrombocytosis and leukocytosis, and elevated serum alkaline phosphatase activity and prothrombin times occurred in dogs. Leukopenia, thrombocytopenia, and azotemia were noted only in monkeys. The anemia was most pronounced during the first 2 weeks of treatment, and despite continued treatment, recovery was well underway in most animals by the end of the treatment period. Histopathology findings were limited to deposition of iron pigment in livers of dogs.
A description is given of a case of neonatal icterus and hemolytic anemia in a Danish boy in whose blood the activity of G-6-PD was markedly reduced. Icterus appeared already one hour after delivery and serum bilirubin reached a maximum value of 16.4 mg/100 ml on the fourth day of life. Anemia was present from the second day of life and progressed during the first month to a minimal concentration of Hb of 5.2 g/100 ml. Normal activities were found in his parents and sister.
A simple procedure for the diagnosis of erythrocyte glucose-6-phosphate dehydrogenase deficiency in Negro males experiencing hemolytic crisis is described. By measuring enzyme activity in the persisting older erythrocytes, the deficiency can be recognized without having to wait until the hemolytic episode and its reticulocyte response have subsided.
Glucose-6-phosphate dehydrogenase (G6PD) levels are not usually drawn in the evaluation of black neonates with hyperbilirubinemia because of the oft-stated opinion that the levels may be normal at the time of hemolysis and thus will be misleading. In fact, this opinion is not applicable to newborns as many studies have shown that deficiency in the conjugating ability of the liver, not hemolysis, is the main cause of neonatal jaundice associated with G6PD deficiency. We present a case report of a neonate with brisk hemolysis and hyperbilirubinemia in whom the G6PD level was abnormally low at the time of the hemolytic episode. DNA analysis showed him to have the A-(202A,376G) variant and, as well, the UGT1A1 promoter repeat polymorphism associated with Gilbert's disease. This case, as well as a review of the literature, indicates that enzyme levels are not normal in patients with G6PD A- who are undergoing hemolysis.
Glucose-6-phosphate dehydrogenase deficiency serves as a prototype of the many human enzyme deficiencies that are now known. Since its discovery more than 50 years ago, the high prevalence of the defect and the easy accessibility of the cells that manifest it have made it a favorite tool of biochemists, epidemiologists, geneticists, and molecular biologists as well as clinicians. In this brief historical review, we trace the discovery of this defect, its clinical manifestations, detection, population genetics, and molecular biology.
A case of hyperbilirubinemia in a newborn Chinese infant, due to G-6-PD deficiency, is presented. Family study revealed two severely affected maternal uncles. The mother, maternal grandmother, two maternal aunts, and four female cousins appeared to be heterozygous female carriers. In a small survey of 53 healthy Chinese adults, moderate to severe G-6-PD deficiency was found in three males, or an incidence of approximately 5.6%.
A new type of screening procedure for the detection of enzymatic defects of the red cell has been described. The blood or red cell sample is added to the reaction mixture. After a suitable period of incubation a drop of the mixture is spotted on filter paper, permitted to dry, and examined for fluorescence under UV light. In this way the oxidation of reduction of pyridine nucleotides is readily evaluated. Reaction mixtures for the detection of glucose-6-phosphate dehydrogenase deficiency, pyruvate kinase deficiency, and glutathione reductase deficiency are described. The same general procedure should be readily adaptable to the detection of other enzymatic deficiencies of red cells, such as phosphogluconate dehydrogenase deficiency or triosephosphate isomerase deficiency.
Several modifications of BREWER's methemoglobin reduction test are described. Among them, the lyophilization of both sodium nitrite and methylene blue solutions into a single vial improves the stability of these reagents. These modifications, extensively checked, do not impair the sensibility of the methemoglobin reduction test.
include fava beans, antimalarial drugs such as primaquine, sulfonamides, and a number of other drugs, many of which are in common use.3-4 A type of congenital nonspherocytic hemolytic anemia is also associated with this enzy- matic defect.#{176}9 In view of its high incidence among American Negroes, G-6-PD deficiency represents one of the commonest potential causes of hemolytic anemia in the United States. A similar situation exists in many other areas of the world. For this reason, there has been considerable demand for a simple, inexpensive, and rapid method for detection of this condition. The procedure outlined below has been developed to meet this need. It will be seen that the major advantages of this method are its simplicity and the stability and reliability of reagents. a. The dipotassium salt of glucose-6-phosphate and the monosodium salt of triphos- phopyridine nucleotide were obtained from Sigma Chemical Co. of St. Louis, Mo., and from California Corp. for Biochemical Research. b. Phenazine methosulfate was obtained from Sigma Chemical Co. It is a light brown powder, lemon-yellow in aqueous solution. It is very unstable to light. Stability is en- hanced by acidification. c. MTT (3( 4,5 dimethylthiazolyl 1-2)2,5 diphenyltetrazohium bromide) is produced by Nutritional Biochemical Co. of Cleveland, Ohio; by Gurr, Ltd. of London, England; and by Dr. H. Harms of Leverkusen, German Federal Republic. Samples have been tested from each of these sources and are fully reactive in the system described below. In the oxidized state, MTT is a light yellow powder which is slightly soluble in water. In the reduced (formazan) state, it is purple, water-insoluble, heat-stable, and relatively light- stable.
Der vonMotulsky eingefhrte Farbtest zum Nachweis der Aktivitt der Glucose-6-Phosphatdehydrogenase in menschlichen Erythrocyten, der auf der Entfrbung eines Redoxfarbstoffs (Brillantkresylblau) durch H+ aus dem Hexosemonophosphatshunt beruht, wurde wie folgt modifiziert:1.
Einfhrung einer normierten Beleuchtung durch eine Lampe trug der bisher nicht bekannten Lichtempfindlichkeit der Reaktion Rechnung.
2.
Durchperlung des Ansatzes mit Kohlenmonoxyd vor Einleitung der Reaktion beschleunigte die Entfrbung auf das 4–5fache;
3.
Benutzung von Methylenblau verbesserte die Ablesung des Farbumschlags.
Der Test ist uerst einfach und bentigt keinen apparativen Aufwand von Belang, die erforderliche Blutmenge ist sehr klein (0,02 bzw. 0,05 ml). Auch bei nicht vllig frischen Blutproben ergeben sich zuverlssige Resultate.
The sex-linked electrophoretic variants A and B of glucose-6-phosphate dehydrogenase were studied in 86 samples of myometrium and 27 leiomyomas from five heterozygous women. All but one sample of myometrium had both A and B bands in equal or nearly equal amounts. In contrast to this, all of the leiomyomas had either an A band or a B band. Both A and B tumors were found in all uteri. These findings are consistent with the hypothesis that these tumors arose from single cells.
HYPERSUSCEPTIBILITY to the hemolytic effects of such oxidant compounds as primaquine, acetylphenylhydrazine and sulfonamides may exist for a number of reasons, by far the most common of which is deficiency in the enzyme glucose-6-phosphate dehydrogenase (G6PD). Although this enzyme deficiency is best identified by quantitative assay, a number of presumptive, or screening, tests have been devised that are better suited to routine hematologic laboratories. These include the procedures originated by Beutler and his associates in which the representative hemolytic compound, acetylphenylhydrazine, was incubated with suspect blood and the red cells were examined for the number of Heinz bodies1 or for . . .
A simple screening test for detecting red cell D-glucose-6-phosphate: NADP oxidoreductase (G-6-PD) deficiency has been devised. The test requires only one reagent, methylene blue, and can be completed after only a twenty minute incubation period. Ten G-6-PD deficient patients were recognized by this test out of a total of 205 male subjects that were screened. Three female Negro subjects with intermediate levels of G-6-PD activity were also recognized out of a total of 27 who were studied. No false positive or false negative results were encountered.
In the assay for glucose-6-phosphate dehydrogenase, and 6-phosphogluconate dehydrogenase, it is shown that hemolysis with saponin or digitonin gives somewhat higher values than those obtained with hemolysis by water. These hemolytic agents apparently free the enzymes from the stroma while hemolysis in water accomplishes this only to a partial and variable degree. This fact leads to a simplified assay in which washed red cells are pipetted into a saponin solution in the cell of the ultraviolet spectrophotometer and combined reagents (which can be stored frozen) are added. The generation of NADPH, followed at 340 mμ, is linear for several minutes. The stoichiometry of the two reactions has been carefully rechecked, and it is concluded that the only valid measurement of glucose-6-phosphate dehydrogenase activity is obtained by subtracting the activity with 6PG as substrate from the activity with G6P and 6PG as combined substrate. The second reaction is roughly the speed of the first reaction but varies from individual to individual.
The erythrocytes of primaquine-sensitive and nonsensitive individuals not receiving primaquine have been compared in the following respects: (a) morphology; (b) antigenic characteristics; (c) sensitivity to acid hemolysis; (d) hemoglobin type; (e) mechanical, osmotic, and chemical fragility; (f) the fragility to the in vitro hemolytic action of primaquine, pamaquine, 6-methoxy-quinoline, quinoline, and aniline; and (g) susceptibility to the accelerating effect of naphthalene and primaquine on taurocholate or saponin hemolysis. The morphology, Coombs' tests, hemoglobin type, and osmotic and mechanical fragility of the erythrocytes have also been studied during the various phases of the hemolytic reaction.
The administration of primaquine to six drug-sensitive recipients in daily doses of 30 mg. base resulted in acute hemolysis followed by complete hematological recovery, although drug administration was continued. Studies with Cr51-labeled erythrocytes demonstrated an abrupt decrease in the rate of hemolysis after about a week of drug administration. This was confirmed by clearing of the urine and a return of reticulocyte counts to lower levels. The self-limitation of the hemolysis was shown to he due to a change in the reactivity of the red cell population. The capacity of drug-sensitive volunteers to hemolyze known primaquine-sensitive cells was not altered during long-term drug administration. Prolonged administration of 30 mg. primaquine base daily (50 to 135 days) to six men produced no other evidence of toxicity.
Erythrocytes of uniform age from a primaquine-sensitive individual were labeled with Fe59. When the labeled erythrocytes were 8 to 21 days old, they were insensitive to the hemolytic action of primaquine; 55 days later the same cells were rapidly destroyed when another course of primaquine was administered. This finding further strengthens the relationship between hemolysis by primaquine and hemolysis by certain aniline derivatives. The increased sensitivity of older cells is believed to suggest that a deficiency in one of the red cell enzymes may play a role in primaquine sensitivity.
The erythrocytes of individuals sensitive to the hemolytic action of primaquine constitute a distinct "group." These erythrocytes form Heinz bodies more readily than do nonsensitive red cells, both under in vivo and under in vitro conditions. A standardized test procedure, based on the difference in in vitro Heinz body formation by acetylphenylhydrazine, is described. Tests of the blood of 104 volunteers, 18 sensitive and 86 nonsensitive, indicated a degree of accuracy exceeding 98 per cent in predicting primaquine sensitivity. Negative test results were obtained on the blood of patients with Hodgkin's disease, multiple myeloma, thallasemia, paroxysmal nocturnal hemoglobinuria, polycythemia rubra vera, and hemoglobin C-S disease. The influence of the composition and age of the buffered acetylphenylhydrazine solution, quantity of blood added, incubation time and temperature, and degree of oxygenation are all described. The degree of oxygenation, in particular, was shown to markedly affect Heinz body formation, oxygen promoting Heinz body formation. Heinz body formation by phenylhydrazine, primaquine, hydroxylamine, and ascorbic acid in sensitive and nonsensitive cells was also compared. The mechanism of Heinz body formation by this group of substances may be oxidation of a red cell component. Sensitive cells may be deficient in a protective enzyme system.
1. Experience with GSH stability test performed on blood samples to which glucose has been added is summarized and the procedure is recommended for routine use for the detection of sensitive subjects.
2. Glutathione stability of erythrocytes has been studied in various population groups of Israel. No case with instable GSH has been found among Jewish subjects originating from Eastern, Central or Western Europe. Instability of GSH was however found in about 20 per cent of subjects originating from Iraq and about 5 per cent of subjects originating from Yemen or North Africa. Isolated cases of this abnormality were also discovered among a small number of persons from other Oriental or Mediterranean countries as well as among the Arab inhabitants of Israel.
3. The genetic analysis points to a transmission of glutathione instability by a sex-linked, incompletely dominant gene with variable expressivity.
4. Variable expressivity of glucose-6-phosphate dehydrogenase activity has also been detected in the defective erythrocytes.
1. Two cases of naphthalene hemolytic anemia in the newborn period are reported.
2. Both exhibited glutathione instability upon incubation with acetyl phenylhydrazine and naphthol months to years later. Several members of their families exhibited a similar defect with evidence that it is inherited as a simple dominant.
3. In those individuals with glutathione instability there was deficient TPNH2 generation by their hemolysates in the presence of glucose-6-phosphate and TPN, indicating a deficiency in glucose-6-phosphate dehydrogenase activity. Glutathione reductase activity was normal or decreased.
4. TPNH2-linked reduction of methemoglobin by erythrocyte suspensions in the presence of glucose and methylene blue was also decreased in those subjects tested, a finding consistent with the deficiency in glucose-6-phosphate dehydrogenase.
It has been recognized for a long time that 8-aminoquinoline compounds may cause hemolytic anemia in certain individuals, but until recently the mechanism of such sensitivity has remained obscure. The use of modern hematologic technics for the study of primaquine sensitivity has resulted in the discovery of a new intrinsic red cell defect. Cells with this defect are sensitive to hemolysis by a large number of aromatic amino compounds, including primaquine and other 8-aminoquinoline derivatives.
Administration of primaquine to sensitive subjects results in destruction of the older members of the red cell population. Available evidence suggests that the administration of a hemolytic drug causes oxidative damage to either the hemoglobin and/or the stroma of the sensitive cell. Heinz bodies are visible manifestation of such damage. The damaged red cells are removed from the circulation by in vivo mechanisms, presumably by the reticulo-endothelial system.
Red cell glutathione has been found to be related in some way to sensitivity to these compounds: (1) the glutathione level of sensitive cells is consistently lower than that of nonsensitive cells; (2) poisoning of the sulfhydryl groups of red cells causes nonsensitive cells to react like sensitive cells in vitro with respect to Heinz body formation; (3) a rapid fall in the red cell glutathione level occurs in vivo when primaquine is administered to sensitive individuals but not to nonsensitive ones; and (4) a rapid fall in GSH level occurs in sensitive but not in nonsensitive cells when they are incubated with acetyl phenylhydrazine and many other compounds. These observations indicate that there is a mechanism that protects GSH in the nonsensitive but not in sensitive cells. This mechanism was found to require presence of glucose or inosine. In sensitive cells, this mechanism is defective and the GSH of the older cells is destroyed. The GSH destructive effect appears in vitro, at least, to be exerted through the oxyhemoglobin.
Primaquine-sensitive red cells have been found to be deficient in glucose-6-phosphate dehydrogenase activity. Glucose-6-phosphate dehydrogenase is involved in TPN reduction.45 TPN is a coenzyme for GSH reduction.103 Thus, a deficiency in glucose-6-phosphate dehydrogenase could result in defective GSH reduction and may therefore serve as an explanation of the GSH instability of drug-sensitive red cells.
It is not clear whether GSH serves merely as a convenient indicator of important changes within the cell that actually lead to cell death or whether GSH depletion plays a primary role in cell death and hemolysis. The role of GSH in the red cell is unknown, and evidence that GSH depletion leads to hemolysis has been obtained only by means which may be grossly injurious to the red cell in many other ways.51,75,116 It is entirely possible that another effect of G-6-P.D., such as TPNH deprivation, leads to cell damage in some entirely different way. Inability to reduce TPN might, for example, interfere with lipid synthesis in the red cell.77
It cannot even be considered clearly established that either the GSH instability or G-6-P.D. deficiency of these red cells is the primary defect leading to susceptability to hemolysis. If the level of G-6-P.D. alone governs the red cell’s resistance to hemolysis, one might expect mild enzyme deficiency to result in mild susceptibility to hemolysis. According to preliminary data reported by Alving et al.,2 this is not the case. The possibility must be considered, therefore, that not only GSH changes but even the G-6-P.D. changes in sensitive cells may be associated defects rather than of primary etiologic significance.
Primaquine-sensitive red cells are also uniquely sensitive to the hemolytic effect of many other compounds, including acetanilid, Furadantin and other drugs commonly used in medicine. Yet, it would appear that many of these drugs can also on occasion cause hemolysis of normal red cells. Subjects who are sensitive to the fava bean have also been shown to have the same defect in GSH stability and glucose-6-phosphate dehydrogenase as primaquine-sensitive individuals display, but here other, as yet unknown, predisposing factors would seem to be involved.
The red cell defect of primaquine-sensitivity is genetically transmitted, probably as a sex-linked gene with intermediate penetrance.
It has thus been shown that a drug-sensitivity reaction is intimately related to a genetically transmitted enzyme deficiency. It is entirely possible, as has been pointed out so effectively by Motulsky,95 that other drug sensitivities may have a similar basis.
HEREDITARY susceptibility to hæmolysis by drugs and fava beans is believed to be due to a single sex-linked gene. This mode of inheritance would best explain the familial and population data, as summarized recently by Childs and Zinkham1. The main element of uncertainty regarding this hypothesis arises from the great variability of the measured blood abnormalities in heterozygous females (in vitro glutathione stability test and glucose-6-phosphate dehydrogenase activity).
A colorimetric method for estimation of glucose-6-phosphate dehydrogenase activity of erythrocytic hemolysates is described. The method reported employs phenazine methosulfate as an electron carrier between TPNH formed in the reaction and dichloroindophenol. Rate of reduction of the latter compound is followed spectrophotometrically. The method gives turnover rates comparable to those obtained with the ultraviolet spectrophotometric method and is more sensitive than the latter. The assay utilizes a standard spectrophotometer or photoelectric colorimeter and is independent of diaphorase activity. The method should be readily adaptable to visual estimation of glucoses-phosphate dehydrogenase of erythrocytes.
Ohno and Hauschka 1 showed that in female mice one chromosome of mammary carcinoma cells and of normal diploid cells of the ovary, mammary gland and liver was heteropyknotic. They interpreted this chromosome as an X-chromosome and suggested that the so-called sex chromatin was composed of one heteropyknotic X-chromosome. They left open the question whether the heteropyknosis was shown by the paternal X-chromosome only, or the chromosome from either parent indifferently.
The 8-aminoquinolines, and many other drugs, cause an acute intravascular haemolysis, known as primaquine-sensitivity, in a certain percentage of persons, particularly the darker-skinned peoples of the world. Massive drug programmes for the eradication of malaria in whole population groups frequently call for the use of primaquine; in addition, the use of other haemolytic or potentially haemolytic drugs in clinical medicine is widespread. Thus it is becoming increasingly important to be able to identify primaquine-sensitive individuals in field and clinical laboratories. Two modifications of a new test for primaquine-sensitivity, the methaemoglobin reduction test, are described in detail in this paper. The more simple modification, the field screening test, is practical for surveying large population groups in the field. The more accurate clinical test is also suitable for field use if a clinical spectrophotometer or photoelectric colorimeter is available.
The importance of glucose-6-phosphate dehydrogenase deficiency in the causation of severe neonatal jaundice in Israel was investigated. Communities with very high frequencies of enzyme deficiency and those in which it was very rare did not differ significantly in the frequency of severe neonatal jaundice not due to iso-immunization. However, in one investigated sample of Iraqi Jews the number of enzyme-deficient cases among the jaundiced infants was significantly higher than expected from the gene frequency, suggesting that some cases of haemolytic disease of newborn due to enzyme deficiency did occur in this group. With one exception all the cases were mild and, did not require exchage transfusion. The overall results suggest that although a few such cases may occur in this country, glucose-6- phosphate dehydrogenase deficiency cannot be considered an important aetiological factor in the causation of severe haemolytic neonatal jaundice in Israel, in spite of the existence of population groups with a very high frequency of the enzyme deficiency. The possible causes of differences between the findings in Israel and those reported from Greece, Sardinia and Malaya are discussed.
Serial determinations of hematocrit, reticulocyte, and bilirubin values were carried out during the first 8 days of life in 30 fullterm primaquine-sensitive Negro infants placed on three different schedules of vitamin K prophylaxis: 10 did not receive vitamin K, 10 were given 2.5 to 7.5 mg of the tetrasodium diphosphate salt of menadione (Synkavite) intramuscularly, and 10 received 1.0 to 18.75 mg of vitamin K1 (Konakion) intramuscularly during the first 24 hours of life. Similar observations were made on 60 full-term Negro infants who had normal or only slightly decreased levels of erythrocyte glucose-6-phosphate dehydrogenase activity. Although none of the infants manifested bilirubin levels greater than 14.5 mg/100 ml, the values in the primaquine-sensitive infants not given vitamin K were significantly higher than those observed in the other babies on the fifth and eighth days of life. The bilirubin values in all the infants were similar during the first day of life; maximal levels, however, occurred later in 5 of the 10 primaquine-sensitive infants who did not receive vitamin K.
Reticulocyte counts were elevated in many of the primaquine-sensitive infants, regardless of their vitamin K grouping. The primaquine-sensitive infants could not be differentiated from normal babies on the basis of hematocrit values, the occurrence of Heinz bodies, and the morphology of the erythrocytes.
The suggestion is made that primaquine-sensitive Negro newborn infants have a shortened survival time of the erythrocyte, predisposing them to the development of hyperbilirubinemia. Furthermore it is suggested that the capacity of some primaquine-sensitive infants to maintain normal bilirubin levels in the face of increased bilirubin formation is affected by the administration of vitamin K1.
Reasons are given for using vitamin K1 rather than the water-soluble analogues of vitamin K, in the prophylaxis of hemorrhagic disease of the newborn. A dose of 18.75 mg of vitamin K1 was given safely to four primaquine-sensitive full-term Negro newborn infants. Until there is conclusive evidence that these large doses are necessarily beneficial, then no more than 2.0 mg of vitamin K1 should be given to these infants.
The main clinical features in 135 infants with severe jaundice or anaemia due to G-6PD deficiency are described. In 130 of the infants jaundice was the main clinical manifestation. Of the 112 infants studied in the neonatal period 87 were boys and 25 girls, and in 33 kernikterus was present on admission. 12 infants were seen later with sequelae of kernikterus and 11 died from this cause, and only their families were studied. Among the 135 infants, 36 were either exposed to naphthalene inhalation or received vitamin K analogues. In the remaining cases no exogenous haemolytic factor was detected. In the majority, jaundice appeared on the second and third day and reached a decisive point between the third and fifth day of life. In a few cases jaundice appeared later, and four infants developed kemikterus after the first week of life.
Details of a simple screening test for the detection of red cell glucose-6-phosphate dehydrogenase deficiency are presented. The test employs capillary blood and one reagent, and is read microscopically. Excellent correlation has been found between the results of this screening procedure and enzyme assay in the detection of enzyme deficiency in patients.
Two variants of glucose-6-phosphate dehydrogenase (G-6-PD), which differ from the common A and B forms of the enzyme by their slow migration on starch gel electrophoresis, have been identified in red cells from Negroes. These variants are tentatively designated Austin 1 and Austin 2. Distribution of each variant among family members is consistent with sex-linked inheritance. Two persons with Austin 1 and two with Austin 2 were found in a survey of 172 unrelated Negroes. The G-6-PD activity of each variant per unit of hemoglobin in hemolyzates was less than the activity for the B form of G-6-PD by magnitudes greater than two standard deviations from the mean for twenty samples of the B form. Since kinetic and lability characteristics of the two variants do not differ from those of the A and B forms of G-6-PD, the molecular differences in the variant enzymes which alter their electrophoretic mobility may exist at sites other than the catalytic sites. Persons with the variant ensymes were not anemic.