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PubMed2000

Human mutations in glucose 6-phosphate dehydrogenase reflect evolutionary history.

Glucose 6-phosphate dehydrogenase (G6PD) is a cytosolic enzyme encoded by a housekeeping X-linked gene whose main function is to produce NADPH, a key electron donor in the defense against oxidizing agents and in reductive biosynthetic reactions. Inherited G6PD deficiency is associated with either episodic hemolytic anemia (triggered by fava beans or other agents) or life-long hemolytic anemia. We show here that an evolutionary analysis is a key to understanding the biology of a housekeeping gene. From the alignment of the amino acid (aa) sequence of 52 glucose 6-phosphate dehydrogenase (G6PD) species from 42 different organisms, we found a striking correlation between the aa replacements that cause G6PD deficiency in humans and the sequence conservation of G6PD: two-thirds of such replacements are in highly and moderately conserved (50-99%) aa; relatively few are in fully conserved aa (where they might be lethal) or in poorly conserved aa, where presumably they simply would not cause G6PD deficiency. This is consistent with the notion that all human mutants have residual enzyme activity and that null mutations are lethal at some stage of development. Comparing the distribution of mutations in a human housekeeping gene with evolutionary conservation is a useful tool for pinpointing amino acid residues important for the stability or the function of the corresponding protein. In view of the current explosive increase in full genome sequencing projects, this tool will become rapidly available for numerous other genes.

Amino Acid Sequence↗

PubMed1991

Evidence for clonal development of Wilms' tumor.

To assess the clonality of Wilms' tumor, glucose-6-phosphate dehydrogenase (G6PD) enzymes were studied in normal and tumor tissue from 11 black girls who were heterozygous for G6PD. Normal tissues expressed both A and B type G6PD, whereas only a single G6PD enzyme was found in all tumor specimens. These data support the clonal nature of Wilms' tumor. In the one patient with bilateral disease, type B G6PD was found in both a recurrence and a subsequent tumor in the contralateral kidney. This finding is consistent with either the chance occurrence of the same G6PD in independent tumors or persistence of the original malignant clone. Another patient, who presented with the nephroblastomatosis complex (a precursor of Wilms' tumor), also had only type B enzyme detected. Further studies in patients with bilateral disease or the nephroblastomatosis complex, including the use of molecular biologic probes, are needed to test the hypothesis that Wilms' tumor in these cases arises from a somatic mutation as a second event in persons with an underlying genetic alteration.

Child↗

PubMed1979

Favism: erythrocyte metabolism during haemolysis and reticulocytosis.

The reduced activity of glucose-6-phosphate dehydrogenase (D-glucose-6-phosphate; NADP+ 1-oxidoreductase; G6PF) in Mediterranean erythrocytes explains the precarious equilibrium of the hexose monophosphate pathway (HMP) and the susceptibility of these cells to haemolytic agents. G6PD-deficient erythrocytes, in steady-state conditions, have a low NADPH/NADP+ ratio, thus allowing the HMP to operate at its maximal intracellular rate and to compensate the intrinsic erythrocyte enzyme deficiency. Studies started soon after accidental intake of fava beans by sensitive G6PD-deficient subjects demonstrate a decrease of both NADPH/NADP+ ratio and reduced glutathione. The metabolic effects induced by fava beans may be attributed to oxidative stress probably associated with an inhibitor effect of some unknown metabolite on the HMP. The availability of erythrocytes from subjects recovering from haemolysis with high reticulocyte counts and increased G6PD activity, provides new information on the rate of synthesis as well as on the in vivo decay of the mutant enzyme. Correlation of G6PD activity to reticulocyte count and extrapolation to an ideally homogenous population of reticulocytes reveal that the mutant enzyme is synthesized at a nearly normal rate. Furthermore, the present correlation allows an estimate of the in vivo half-life of Mediterranean G6PD. The rate of decline of about 8 d observed in this study well correlates to the intracellular metabolic aspects of G6PD Mediterranean erythrocytes.

Adolescent↗

PubMed1979

Glucose-6-phosphate dehydrogenase deficiency and neonatal jaundice in Jamaica.

Glucose-6-phosphate dehydrogenase (G6PD) deficiency was detected in 16 (69.6%) of a group of 23 neonates who had unexplained moderate or severe jaundice. This proportion is significantly more than the 9.4% observed or the 22.2% expected in Jamaican neonates who are not moderately or severely jaundiced (P less than 0.003), and significantly more than the 12.6% observed or the 21.0% expected in older Jamaican children and adults (P less than 0.003). Phenobarbitone therapy and phototherapy reduced the need for exchange transfusion but this was necessary in eight patients. Two babies developed kernicterus and one died. On the other hand, only two of 21 neonates who were identified as G6PD deficient at birth subsequently became moderately or severely jaundiced, and this could be attributed to other causes in both cases. These findings indicate that apparently spontaneous neonatal jaundice is important in infants who have the G6PD A--enzyme. However, the jaundice is probably precipitated by unknown factors to which the G6PD deficient neonate is more susceptible than the infant who is not G6PD deficient. THere is also a slightly increased incidence of G6PD deficiency in neonates who develop jaundice because of ABO or Rh(D) iso-immune disease, infection or prematurity.

Adolescent↗

PubMed1993

Posttransfusional hemolysis in recipients of glucose-6-phosphate dehydrogenase-deficient erythrocytes.

To test the hypothesis that transfusion of blood donated by individuals with glucose-6-phosphate dehydrogenase (G6PD) deficiency may result in a hemolytic reaction, we conducted a prospective longitudinal study in which 10 patients transfused with 1 unit of G6PD-deficient and 1 unit of normal red blood cells (RBC) were compared with 10 patients transfused with 2 units of age-matched normal RBC. We found that 24 h after transfusion serum bilirubin (mumol/l) in the recipients of G6PD-deficient RBC was significantly higher than in the recipients of normal RBC (36 +/- 14 vs. 18 +/- 5, respectively, p > 0.004). A parallel increase was found in the serum lactate dehydrogenase (LDH; IU/l) between the two groups (378 +/- 151 vs. 264 +/- 56, p < 0.001). The difference in serum bilirubin (26 +/- 10 vs. 15 +/- 5, p < 0.03) was still noted 48 h after transfusion, with only a marginal difference (p < 0.08) in LDH. We conclude that an immediate posttransfusional hemolytic reaction can occur in recipients of G6PD-deficient RBC and therefore suggest that the differential diagnosis of posttransfusional hemolysis, particularly in populations where G6PD deficiency is prevalent, includes transfusion of erythrocytes from G6PD-deficient donors.

Glucosephosphate Dehydrogenase Deficiency↗

PubMed1988

The production of normal and variant human glucose-6-phosphate dehydrogenase in cos cells.

Full-length cDNA coding for human glucose-6-phosphate dehydrogenase (G6PD) was inserted into a eukaryotic expression vector containing the immediate early promoter of cytomegalovirus. When this plasmid was introduced into cos cells by transfection it led to the production of high levels of human G6PD. cDNAs containing mutations found in G6PD-deficient individuals were constructed by in vitro mutagenesis and expressed in the same system. Characterization of the G6PD proteins obtained in this way confirmed the primary structure inferred for the variant enzymes. An enzyme in which lysine-205 had been mutated to threonine was produced and found to have no G6PD activity, proving that this lysine residue is essential for enzyme activity in human G6PD.

Cell Line↗

PubMed1994

Glucose-6-phosphate dehydrogenase enzyme activity of normal term Malaysian neonates of different ethnic origins.

The cord blood glucose-6-phosphate dehydrogenase (G6PD) enzyme activity of 262 normal term Malaysian neonates (92 Malays, 96 Chinese and 74 Indians) was quantitatively determined by the World Health Organisation method. Analysis of variance for the levels of G6PD enzyme activity by ethnic origin and sex showed that there was a significant difference between mean levels of enzyme activity in the three ethnic groups (P = 0.03) but no difference between the sexes (P = 0.36). Multiple range analysis showed that Malays had significantly higher mean levels of G6PD enzyme activity than those of Chinese (P = 0.01). There was no significant difference between the mean levels of G6PD enzyme activity of Chinese and Indians (P = 0.52), nor was there any difference between those of Malays and Indians (P = 0.08). The difference in levels of G6PD enzyme activity among the different ethnic groups could be due to the existence of different G6PD variants.

Analysis of Variance↗

PubMed1996

The prevalence of hemoglobin S and glucose-6-phosphate dehydrogenase deficiency in Jordanian newborn.

OBJECTIVE: The aim of this study was to determine the incidence of HbS and glucose-6-phosphate dehydrogenase (G6PD) deficiency in Jordanian newborn. STUDY DESIGN: A total of 181 male and female babies born at Princess Basma Teaching Hospital, randomly selected, and cord blood samples were collected, and the erythrocyte G6PD activity was measured, and the hemoglobin electrophoresis for blood lysate was conducted and scanned for HbS scanning. RESULTS: The frequencies of two major red cell genetic defects, sickle hemoglobin (HbS) and deficiency G6PD was determined, of the studied subjects 10 (11%) females and 11 (12%) males were found to be deficient in the G6PD gene. The frequency of HbS carriers among the females was 4% while it was 6% among males. The coincidence of both G6PD deficiency and sickle cell hemoglobin in the samples was 1%. No coincidence was found between G6PD deficiency and hyperbilirubinemia. CONCLUSION: A better understanding of the distributions of these genetic disorders has the potential to aid in the more efficient utilization of health care resources and improved planning.

Erythrocyte Count↗

PubMed1998

N-acetylcysteine reduces methemoglobin in an in-vitro model of glucose-6-phosphate dehydrogenase deficiency.

OBJECTIVE: To determine whether N-acetylcysteine (NAC) reduces methemoglobin (MHB) in an in-vitro model of glucose-6-phosphate dehydrogenase (G6PD) deficiency, given that methylene blue is an ineffective MHB antidote in G6PD deficiency. METHODS: Five volunteers donated blood, which was divided equally into 2 test tubes, centrifuged, and washed with Tris-Mopps buffer (pH 7.4, 15 mmol/L glucose). Both tubes were incubated with epiandrosterone (EA) (400 micromol), a specific inhibitor of G6PD. After 75 microL of 0.18 mol hydroxylamine (HA) was added to induce MHB formation, 150 microL of NAC (20 mg/mL) was added to tube 1 and 150 microL of phosphate-buffered saline (PBS) was added to tube 2 as a volume control. Serial MHB levels are reported as a percentage of total hemoglobin (Hb). G6PD activity was measured at baseline, 15 minutes after EA, and at 5 hours. RESULTS: Mean G6PD activity at baseline was 9.2+/-2.9 U/g Hb (normal >4.6 U/g Hb); 15 minutes after EA was 3.0+/-1.0 U/g Hb; and at experiment's end was 2.3+/-0.7 U/g Hb. The mean (+/-SD) areas under the concentration-time curves (AUCs) of NAC-EA-HA and PBS-EA-HA samples were compared using an unpaired t-test and were significantly different: PBS-EA-HA, 20,400+/-1,100 % min, vs NAC-EA-HA, 10,400+/-1,000 % min, respectively (p < 0.05). CONCLUSION: In this in-vitro model of G6PD deficiency, NAC efficiently reduced MHB.

Acetylcysteine↗

PubMed1981

Glucose-6-phosphate dehydrogenase status and neonatal jaundice.

Neonatal jaundice and its relationship to glucose-6-phosphate dehydrogenase (G6PD) status of healthy, term Chinese infants was evaluated in 220 G6PD-deficient infants, 26 intermediate infants who were observed for 3 weeks, and 116 normal (control) infants. Each infant was free of isoimmunisation, cephalhaematomas, or contusions. The mode of labour, method of delivery, and type of feeds had no appreciable effect on daily bilirubin levels. "Elevated" physiological jaundice was associated with normal and G6PD-deficient status; there was no increased haemolysis. G6PD-deficient status was associated with jaundice significantly raised especially in the first week of life, and prolonged beyond that of the "elevated" physiological jaundice. Significantly increased though mild haemolysis was observed. Close surveillance is therefore required for G6PD-deficient infants at least for the first week of life, the period of increased risk. With G6PD-intermediate infants, only the usual measures for normal infants are required.

Bilirubin↗

PubMed2001

Dietary regulation of expression of glucose-6-phosphate dehydrogenase.

The family of enzymes involved in lipogenesis is a model system for understanding how a cell adapts to dietary energy in the form of carbohydrate versus energy in the form of triacylglycerol. Glucose-6-phosphate dehydrogenase (G6PD) is unique in this group of enzymes in that it participates in multiple metabolic pathways: reductive biosynthesis, including lipogenesis; protection from oxidative stress; and cellular growth. G6PD activity is enhanced by dietary carbohydrates and is inhibited by dietary polyunsaturated fats. These changes in G6PD activity are a consequence of changes in the expression of the G6PD gene. Nutrients can regulate the expression of genes at both transcriptional and posttranscriptional steps. Most lipogenic enzymes undergo large changes in the rate of gene transcription in response to dietary changes; however, G6PD is regulated at a step subsequent to transcription. This step is involved in the rate of synthesis of the mature mRNA in the nucleus, specifically regulation of the efficiency of splicing of the nascent G6PD transcript. Understanding the mechanisms by which nutrients alter nuclear posttranscriptional events will help uncover new information on the breadth of mechanisms involved in gene regulation.

Diet↗

PubMed2002

Chronic haemolytic anaemia and glucose-6 phosphate dehydrogenase deficiency. Case report and review of the literature.

Deficiency in glucose-6-phosphate dehydrogenase (G6PD) is the most common enzymopathy, and more than 125 different mutations causing G6PD deficiency have been identified. Chronic haemolytic anaemia (CHA) associated with G6PD deficiency is rare, but there is a cluster of mutations causing CHA between amino acids 361-428 which are encoded by exon 10 of the G6PD gene. This region is involved in the dimer formation of the active G6PD enzyme and therefore plays an important role for enzyme stability and activity. Here, we report a 17-year-old patient with CHA, who carries a rare G --> A mutation at nucleotide 1160 which causes an R387H amino acid substitution. We review the reports of the seven previously described patients with this mutation, concluding that G6PD deficiency should be considered as a rare differential diagnosis of chronic haemolytic, non-spherocytic anaemia.

Adolescent↗

PubMed1975

Erythrocyte glucose-6-phosphate dehydrogenase in the Niokolonko (Malinke of the Niokolo) of Eastern Senegal. Identification of a slow variant with normal activity (Tacoma-like).

In a survey of blood genetic markers in the Niokolonko of Eastern Senegal, three types of G6PD variants were discovered: (1) fast variants, common Negro G6PD A +; the frequency of the Gd A + gene was 0.183; (2) deficient G6PD A--, occurring with a fairly low frequency: 0.079, and (3) some individuals were carriers of a slow moving electrophoretic variant with normal activity. After purification, the analysis of kinetic parameters showed that this enzyme was closely similar to G6PD Tacoma. We proposed to label it 'G6PD Tacoma-like'. The incidence of this mutation in the whole group studied was 0.020. G6PD Tacoma-like may be common in some African tribes.

Erythrocytes↗

PubMed1988

Glucose-6-phosphate dehydrogenase deficiency in Saudi Arabia. A study in Al-Ula.

This paper reports the frequency of glucose-6-phosphate dehydrogenase (G6PD) deficiency in the male and female population of A1-Ula in the northwestern province of Saudi Arabia. The frequency of G6PD deficiency in the male population was 0.098 and in the females it was 0.028. This frequency is significantly lower than those reported for other malaria endemic regions in Arabia. The population was further subgrouped on the basis of their haemoglobin phenotypes and the highest frequency of G6PD deficiency was obtained in male Hb S heterozygotes followed by the male Hb S homozygotes. Phenotyping of G6PD revealed the presence of G6PD-Mediterranean, G6PDA+, G6PDA- and G6PD Mediterranean-like, and the frequency of these variants in Al-Ula was different from those reported in other regions of Saudi Arabia.

Female↗

PubMedDate not supplied

Molecular characterization of glucose-6-phosphate dehydrogenase deficiency in Brazil.

Molecular characterization of glucose-6-phosphate dehydrogenase (G6PD) variants was carried out in 150 unrelated G6PD deficient blood donors from the region of Campinas, Brazil. By allele specific oligomer hybridization or digestion of exon 4 of the G6PD gene with the restriction endonuclease NlaII, we detected the 202 G-->A mutation in 146 individuals. This mutation was associated with the 376 G-->A substitution and only one haplotype was observed in these individuals. Digestion of exon 6 with the restriction enzyme MboII showed the presence of the Mediterranean variant in three individuals. Haplotype analysis showed, in all three samples, a T at nt 1311 and the C at nt 13 in intron 11, suggesting a European origin of this variant. By SSCP analysis and direct sequencing we detected the mutation nt 1003 G-->A (335 Ala-->Thr) in one blood donor. This mutation was previously described in a boy of Indian ancestry and the variant was denominated G6PD Chatam. The case described here has no Indian ancestry; thus, we presume that the mutations have arisen independently, although we do not know the haplotype of the Indian patient. The haplotype of our case was the most common observed in our population (PvuII, BspHI+, PstI+, 1311C, NlaIII-). Thus, our data indicate that G6PD A- with the 202 G-->A mutation is the most frequent G6PD deficiency in the population of southeastern Brazil. The remaining variants had a Mediterranean origin. These results are in agreement with the origin of the Brazilian population.

Brazil↗

PubMed1991

Glucose-6-phosphate dehydrogenase activity in dorsal root ganglia of vitamin E-deficient rats.

The effect of dietary vitamin E on the activity of glucose-6-phosphate dehydrogenase (G6PD) and 6-phosphogluconate dehydrogenase (6PGD) was studied in the dorsal root ganglia of rat. One-month-old male Sprague-Dawley rats were randomly assigned to two dietary treatment groups for 2 months. The first received a standard diet supplemented with vitamin E, the second was fed a basal vitamin E-deficient diet. The activity of G6PD was markedly decreased in ganglia of the deficient animals with respect to the controls. On the other hand, the activity of the 6PGD was not significantly altered in the deficient animals. In the red cells the two enzyme activities presented a similar situation and the level of the reduced glutathione in the red cells was not significantly altered by the status of dietary vitamin E. Kinetic analysis with crude extracts of ganglia or partially purified G6PD demonstrated that there was no direct modulatory effect of the vitamin on the enzyme activity. Moreover, nondenaturing gel electrophoresis performed in this study revealed that none of the three G6PD activity bands which appeared on the acrylamide gel were significantly altered in the deficient animals. At present, the mechanism linking the G6PD activity with the status of dietary vitamin E remains unknown. Our results suggest, however, that a reduced NADPH generation produced by a decay of G6PD activity may limit the glutathione peroxidase, a very active enzyme in detoxifying peroxides, and may predispose the nervous tissue to oxidant injury.

Animals↗

PubMed1989

Glucose 6-phosphate dehydrogenase deficiency both in red blood cells and lenses of the normal and cataractous native population of Cukurova, the southern part of Turkey. Part I.

Glucose 6-phosphate dehydrogenase (G6PD) activity was measured in both red blood cells and lenses of persons with cataracts living in Cukurova, the southern part of Turkey, where G6PD deficiency is well documented. The incidence of red blood cell G6PD deficiency among the patients with cataract (33.3%) was significantly higher than that in individuals with clear lenses (8.2%). The incidence of lens G6PD deficiency in a total of 52 patients with cataract was 52%. Of the lens G6PD-deficient cases, 46.2 and 28.6% of female and male patients, respectively, also showed red blood cell G6PD deficiency.

Adult↗

PubMed1989

Glucose 6-phosphate dehydrogenase deficiency both in red blood cells and lenses of the normal and cataractous native population of Cukurova, the southern part of Turkey. Part II.

A possible correlation between development of cataract and glucose 6-phosphate dehydrogenase (G6PD) deficiency in red blood cells and lenses was investigated. The distribution of cataract types in both G6PD-positive and G6PD-deficient patients, the incidence of G6PD deficiency in cortical cataract groups and the distribution of G6PD-deficient cases according to age were determined. The results showed that quite a high percentage of cortical cataractous patients had G6PD deficiency in both red blood cells and lenses.

Adult↗