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Depression of erythrocyte glucose-6-phosphate dehydrogenase (G6PD) activity in enteric fever.

Ninety adult Indian typhoid and paratyphoid fever (enteric fever, EF) patients and 91 controls were tested for glucose-6-phosphate dehydrogenase (G6PD) deficiency using the fluorescent spot test (FST) and the quantitative methaemoglobin reduction test ( QMRT ). There was a threefold higher incidence of G6PD deficiency in North Indian EF patients (10.6%) than in controls (3.6%) (P = 0.15) which may be attributable to the greater morbidity of the G6PD-deficient EF patients; six of nine had haemolytic anaemia. A transient depression of mean erythrocyte G6PD activity was observed in a subgroup of 49 non-deficient EF patients in whom the spectrophotometric G6PD assay was done. It did not appear to be related to reticulocyte count, chloramphenicol therapy, or differences in leucocyte contamination of the haemolysate used for the G6PD assay. If this depression of G6PD activity occurs in deficient patients as well, it may help to explain the haemolysis seen in them during EF. Of the three tests used, the QMRT and the spectrophotometric assay clearly identified G6PD deficiency in males during haemolysis, whereas the FST was unreliable in this situation.

Adult↗

G6PD: population genetics and clinical manifestations.

The glucose-6-phosphate dehydrogenase (G6PD) gene is X-linked. There are numerous mutations that cause a deficiency of this enzyme in erythrocytes. G6PD deficiency can produce anemia, both when drugs are administered and under the stress induced by infection. Functionally severe variants cause hereditary non-spherocytic hemolytic anemia, i.e. anemia even in the absence of stress. Neonatal jaundice occurs in G6PD deficiency, but it is likely that it is largely due to impairment of liver function, rather than to hemolysis. It has been suggested that there are clinical manifestations of G6PD deficiency that are related to other tissues, but the existence of these is not well documented. Some mutations that produce G6PD deficiency in red cells exist at polymorphic frequencies. Individuals with such mutations seem to have enjoyed a selective advantage because of resistance to falciparum malaria. Different mutations, each characteristic of certain populations, are found, and have been characterized at the deoxyribonucleic acid (DNA) level. G6PD A-(202A376G) is the most common African mutation. G6PD Mediterranean(563T) is found in Southern Europe, the Middle East and in the Indian subcontinent. Several other mutations are common in Asia. Genetic variability of G6PD has played an important role in the understanding of a variety of developmental processes.

Africa↗

Effects of G6PD overexpression in NIH3T3 cells treated with tert-butyl hydroperoxide or paraquat.

The major physiological role of glucose-6-phosphate dehydrogenase (G6PD) is to provide NADPH, which is required for reductive biosynthesis and for detoxification of free radicals and peroxides in mature red blood cells. To study the function of G6PD in non-erythroid cells, we examined the sensitivity of NIH3T3 cells transfected with a plasmid containing human G6PD cDNA to tert-butyl hydroperoxide (TBH) and paraquat. Two transfected clones which had a sixteen-fold (H7 clone) and six-fold (H6 clone) increase in their intracellular G6PD activity were compared with control cells transfected with a vector alone. Cells with high-level expression of human G6PD were 2.3 (H6) to 3.7 (H7) times more resistant to TBH than control cells. The antioxidant (anti-TBH) abilities in H6 and H7 cells were revealed by (1) a significant increase in the intracellular level of NADPH and glutathione, (2) a reduction of fluorescent intensity of the oxidant-sensitive dye, 2',7'-dichlorofluorescin diacetate, and (3) a significant reduction in the production of oxidized adducts generated by lipid peroxidation. In contrast, cells overexpressing G6PD were very sensitive to paraquat, a superoxide-producing herbicide. The concentrations of paraquat required to produce a 50% decrease in cell viability of H7, H6 and control cells were 0.80 mM, 1.14 mM, and 2.19 mM, respectively. The cytotoxicity of paraquat correlated with the expression level of NADPH in the cells. In this study, overexpression of human G6PD in NIH3T3 cells had different effects on the toxicity of TBH vs. paraquat. Reduction of NADP+ to NADPH by G6PD protects cells from oxidative damage by TBH, but appears to enhance the toxicity of paraquat.

3T3 Cells↗

Two new mutations of the glucose-6-phosphate dehydrogenase (G6PD) gene associated with haemolytic anaemia: clinical, biochemical and molecular relationships.

In two unrelated Spanish males with glucose-6-phosphate dehydrogenase (G6PD) deficiency and haemolytic anaemia, and two different novel point mutations in the G6PD gene, have been identified. A C to T transition at nucleotide 406 resulting in a (136) Arg to Cys substitution and a C to G transition at nucleotide 1155 resulting in a (385) Cys to Trp substitution. These two molecular defects have not been described before and are designated G6PD Valladolid 406 C-->T and G6PD Madrid 1155 C-->G. In vitro biochemical characterization of both mutant enzymes showed important differences in their molecular properties according to their different clinical behaviour. In G6PD Valladolid, the mutation of which is located in exon 5, the normal in vitro heat stability may explain its mild clinical expression (low-grade haemolysis interrupted by an acute haemolytic crisis at age 70). In G6PD Madrid, the mutation, located in exon 10, results in a deficient variant associated with neonatal jaundice and life-long chronic nonspherocytic haemolytic anaemia (CNSHA). This finding further emphasizes the importance of this specific region of the G6PD gene in the stabilization of the G6PD molecule. Putative relationships between these single point mutations and the molecular properties of the mutant enzymes are also discussed.

Anemia, Hemolytic↗

Mediterranean glucose 6-phosphate dehydrogenase (G6PD) deficiency--near normal decay of the mutant enzyme protein in circulating erythrocytes.

Complete removal of leucocytes and platelets from erythrocytes and the development of a sensitized procedure for the assay of G6PD activity allowed the biochemical mechanisms of the Mediterranean variety of G6PD deficiency to be re-evaluated. Activity in the young erythrocytes from 9 G6PD-deficient subjects averaged 0.1% of the levels observed in the corresponding erythrocyte fraction from normal individuals: moreover, the decline of activity during aging of the G6PD-deficient erythrocytes was comparable with that observed for the normal enzyme. Mutant G6PD purified from granulocytes of a G6PD-deficient subject and entrapped within the corresponding erythrocytes was remarkably stable. Exposure of native erythrocytes to an oxidative stress (divicine plus ascorbate) resulted in a decrease of G6PD activity that was significantly more rapid and extensive in control than in G6PD-deficient cells. These results seem to exclude enhanced intracellular breakdown of the mutant protein within the circulating erythrocytes.

Ascorbic Acid↗

Exercise-induced oxidative stress in G6PD-deficient individuals.

PURPOSE: This study was designed to investigate whether individuals with glucose-6-phosphate dehydrogenase (G6PD) deficiency can exercise without greater perturbations in their redox status compared with non-G6PD-deficient individuals. METHODS: Nine males with established G6PD deficiency and nine males with normal G6PD activity performed two exhaustive treadmill exercise protocols of different duration (the shorter one lasting 12 min and the longer one 50 min). Several hematological parameters, reduced glutathione (GSH), oxidized glutathione (GSSG), thiobarbituric acid reactive substances (TBARS), protein carbonyls, catalase, and total antioxidant capacity (TAC) were measured in the blood before and after each exercise bout. RESULTS: Both GSH and GSSG were significantly higher in the control group compared with the G6PD-deficient group at baseline (0.404 +/- 0.101 vs 0.195 +/- 0.049 mmol.L(-1) for GSH and 0.047 +/- 0.012 vs 0.012 +/- 0.006 mmol.L(-1) for GSSG; P < 0.05); as a result, their ratio was not significantly different between the two groups (P > 0.05). All other oxidative stress indices were not different between groups at rest (P > 0.05). Exercise of both durations affected significantly (P < 0.05) and similarly the levels of all oxidative stress indices either in the G6PD-deficient group or in the control group. Only the long exercise affected GSH status significantly (P < 0.05), whereas both short and long exercise increased the levels of TBARS, protein carbonyls, catalase activity, and TAC to a similar extent (P < 0.05). CONCLUSION: G6PD-deficient individuals are able to exercise until exhaustion without higher oxidative stress compared with non-G6PD-deficient individuals. Exercise duration is an important determinant of the magnitude of exercise-induced changes for GSH, GSSG, and GSH/GSSG, but not for TBARS, protein carbonyls, catalase activity, or TAC.

Analysis of Variance↗

DNA damage and apoptosis in mononuclear cells from glucose-6-phosphate dehydrogenase-deficient patients (G6PD Aachen variant) after UV irradiation.

Patients affected with X chromosome-linked, hereditary glucose-6-phosphate dehydrogenase (G6PD) deficiency suffer from life-threatening hemolytic crises after intake of certain drugs or foods. G6PD deficiency is associated with low levels of reduced glutathione. We analyzed mononuclear white blood cells (MNC) of three males suffering from the German G6PD Aachen variant, four heterozygote females of this family, one G6PD-deficient male from another family coming from Iran, and six healthy male volunteers with respect to their DNA damage in two different genes (G6PD and T-cell receptor-delta) and their propensity to enter apoptosis after UV illumination (0.08-5.28 J/cm2). As determined by PCR stop assays, there was more UV-induced DNA damage in MNC of G6PD-deficient male patients than in those of healthy subjects. MNC of G6PD-deficient patients showed a higher rate of apoptosis after UV irradiation than MNC of healthy donors. MNC of heterozygote females showed intermediate rates of DNA damage and apoptosis. It is concluded that increased DNA damage may be a result of deficient detoxification of reactive oxygen species by glutathione and may ultimately account for the higher rate of apoptosis in G6PD-deficient MNC.

Adolescent↗

G6PD deficiency in Vataliya Prajapati community settled in Surat.

BACKGROUND: A Study on Vataliya Prajapati was published earlier but heterozygous females were not identified. AIMS: To compare incidence of glucose-6-phosphate dehydrogenase (G6PD) deficiency in random and unrelated subjects, present and previous study and as per their original habitat. Incidence of heterozygous deficiency and clinical implication of deficiency was also determined. SETTINGS AND DESIGN: Camps were organized in Katargaon and Amroli regions. Blood specimens, with relevant demographic information, were collected from those who attended the camp. METHODS AND MATERIAL: A total of 1644 random blood samples were collected from 404 families participating in the camps. Nitroblue tetrazolium dye test was used for G6PD deficiency screening and quantitative assay for measurement of G6PD enzyme activity. STATISTICAL ANALYSIS USED: Chi2 test was used to evaluate significance and mean values were compared by the Student's ''t'' test. RESULTS: Incidence of G6PD deficiency was found as 22% among all the random samples tested. However, the G6PD deficiency among unrelated members was 27.9% in males and 12.4% (P< 0.001,df 1). The 13.9% of the females with heterozygous G6PD deficient status, together with the homozygous deficient phenotype makes the incidence comparable with males. Incidence of deficiency was comparable with previous study, in Katargam and Amroli and in Amerli and Bhavganar districts. Deficient subjects had mild anemia and hemolytic crisis rarely occurred. CONCLUSION: Vataliya Prajapatis have high incidence of G6PD deficiency without severe chronic hemolytic anemia. However before prescribing medicines physician should know the G6PD status of a Vataliya Prajapati patient.

Anemia, Hemolytic↗

Automated determination of glucose-6-phosphate dehydrogenase (G6PD) on a SPOTCHECK Microflow analyzer.

Glucose-6-phosphate dehydrogenase (G6PD) is the initial enzyme in the hexose monophosphate pathway of glucose metabolism. Deficiency of G6PD has been linked to increased sensitivity of red cells to hemolytic anemia due to certain oxidant drugs, infectious agents or fava beans. It is an inherited error in metabolism and has a high incidence in certain ethnic groups. Astoria-Pacific has developed an automated assay for use on the SPOTCHECK Microflow Analyzer for the semi-quantitative determination of G6PD activity in erythrocytes. After sample extraction, all assay steps are automated including reagent addition, incubation and data collection. Use of on-line dialysis removes interferences. The assay is intended primarily as a screening tool in the diagnosis and treatment of disease states associated with G6PD deficiency in newborns. G6PD in the dried blood spot is extracted and placed on the instrument. Samples are then aspirated into the system at a rate of 90 samples/hour. All other reagents are added by the SPOTCHECK Analyzer on-line during sample processing. Incubation of each sample occurs on-line at 37 degrees C, and after dialysis the NADPH reaction product is excited at 365 nm. Fluorescence is measured at 500 nm. A lack of fluorescence indicates a probable G6PD deficiency. Data reduction occurs real time through a FASPac software thus individual results are available during a run as soon as each sample analysis is complete. The Astoria-Pacific International G6PD reagent kit paired with the SPOTCHECK Microflow Analyzer provides an effective and easy to use screening tool for determining G6PD deficiency in newborns.

Autoanalysis↗

[Identification of G6PD mutations in Guangxi by combination of denaturing high performance liquid chromatography, DNA sequencing and restriction endonuclease analysis].

OBJECTIVE: To explore new genotypes of glucose-6-phosphate dehydrogenase (G6PD) deficiency in Guangxi. METHODS: G6PD mutations were identified by combination of denaturing high performance liquid chromatography (DHPLC), DNA sequencing and restriction endonuclease assay. RESULTS: Three cases (10.0%) of G6PD Viangchan (871G-->A, 1311C-->T) and one case (3.3%) of G6PD Union (1360C -->T) were first identified in China mainland. G6PD Ganton (1376G-->T, 30.0%) was the commonest mutation, followed by Kaiping (1388G-->A, 26.7%), and Gaohe (95A-->G, 23.3%). CONCLUSION: Besides G6PD Ganton, Kaiping and Gaohe, there are G6PD Viangchan and Union in Guangxi. G6PD Viangchan and Union is reported for the first time in China mainland.

China↗

Pro-oxidative effects of tea and polyphenols, epigallocatechin-3-gallate and epigallocatechin, on G6PD-deficient erythrocytes in vitro.

Glucose-6-phosphate dehydrogenase (G6PD)-deficient subjects are vulnerable to chemical-induced hemolysis if exposed to oxidative agents. Recent studies reported that green tea and its constituents might act as pro-oxidants. Our objective was to investigate effects of tea and its polyphenolic components on the oxidative status of human G6PD-deficient erythrocytes. Erythrocytes of G6PD-deficient (n = 8) and normal (n = 8) subjects were incubated with water extracts of 3 types of tea samples (black tea, green tea and decaffeinated green tea extract) and 6 polyphenols. The resulting levels of reduced glutathione (GSH) and glutathione disulphide (GSSG), methemoglobin and plasma hemoglobin were quantified by HPLC and biochemical assays. The tea extracts significantly reduced GSH and increased GSSG levels in G6PD-deficient erythrocytes in a dose-dependent manner (0.5-10 mg/ml), but not in normal erythrocytes. Similar dose-dependent responses to (-)-epigallocatechin (EGC) and (-)-epigallocatechin-3-gallate (EGCG), but not to the other polyphenols, were observed. In G6PD-deficient cells, GSH was reduced by 43.3% (EGC at 0.05 mg/ml) and 33.3% (EGCG at 0.5 mg/ml), compared with pre-challenged levels. The concentration of methemoglobin was increased significantly when challenged with tea extracts, and EGC. Plasma hemoglobin levels were higher in G6PD-deficient samples after exposure to tea extracts, EGCG, EGC and gallic acid, compared with those in normal blood. Tea extracts and polyphenols significantly altered the oxidative status of G6PD-deficient erythrocytes in vitro as demonstrated by the decrease of GSH, and increased GSSG, methemoglobin and plasma hemoglobin. Our data caution against the excessive consumption of concentrated tea polyphenolic products by G6PD-deficient subjects.

Adult↗

Nucleotide 1376 G-->T mutation in G6PD-deficient Chinese in Malaysia.

G6PD deficiency is the most common human enzymopathy and affects 200 million people worldwide. To date more than 400 biochemical variants and at least 60 different point mutations in the G6PD locus have been discovered. In Malaysia the overall incidence of G6PD deficiency among males is 3.1%, being more prevalent among the Chinese and Malays and less common among the Indians. As part of our initial effort to characterise G6PD deficiency in the Malaysian population, we investigated 18 G6PD deficient Chinese male neonates for the G6PD mutation G-->T at nt 1376, a common mutation seen among the Chinese in Taiwan and mainland China. The mutation was detected by a PCR-based technique using primers that artificially create a site for restriction enzyme Xho I. We found 61% (11 out of 18) of the Chinese G6PD deficient male neonates positive for this mutation. Study of enzyme electrophoretic mobility in 7 of the cases positive for this mutation revealed three different patterns of mobility. 107% (5 out of 7), 103% (1 out of 7) and 100% (1 out of 7). This study shows that mutation G-->T at nt 1376 is a common allele causing G6PD deficiency in Malaysians of Chinese origin. The finding of different patterns of electrophoretic mobility among the 7 cases positive for 1376 G-->T mutation supports the notion that diverse biochemical variants may share the same mutation.

Asian People↗

Rapid detection of common Chinese glucose-6-phosphate dehydrogenase (G6PD) mutations by microarray-based assay.

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most common human enzymopathy, affecting more than 200 million people worldwide. To date more than 123 mutations in the G6PD gene have been discovered, among which 12 point mutations are found in the Chinese. Setting up a simple and accurate method for detecting these mutations is not only useful for diagnosing G6PD deficiency under some circumstances that it is difficult to measure the activity of the enzyme, but also for studying the frequency of the G6PD genotypes. The purpose of this study was to develop a simple, inexpensive and accurate method for detecting these common mutations. Microarray-based assay was described in this study. Samples from 198 G6PD-deficient persons were investigated. The DNA sequencing data supported the results obtained by microarray-based assay. Thus, we concluded that the microarray-based assay is a rapid, simple, inexpensive, and accurate method for detecting the most common G6PD gene mutations among the Chinese. This method involves the selective amplification of human G6PD gene with specific oligonucleotide primers, fragmentation and labeling of PCR products, followed by hybridization with allele-specific oligonucleotide (ASO) probes on chip.

Asian People↗

G6PD haplotypes spanning Xq28 from F8C to red/green color vision.

The most telomeric region of the human X chromosome within band Xq28 consists of a gene-rich region of about 3 Mb which contains the genes for coagulation factor VIIIc, glucose-6-phosphate dehydrogenase (G6PD), and red/green color vision. We have studied five polymorphic sites from this region, in a sample of normal people from the Cosenza province of Southern Italy. These sites, which span a distance of some 350 kb, are in strong linkage disequilibrium. Of the 32 possible haplotypes only 10 were found, and 4 of these account for 80% of all X chromosomes analyzed. In addition, we found that all G6PD-deficient people with the G6PD Mediterranean mutation belong to only two haplotypes. One of these (Med 1) is found only within a small subregion of the area investigated, west of the Appennine mountain range. Most remarkably, all Med 1 G6PD-deficient individuals also had red/green color blindness. The more frequent haplotype (Med 2) is the same in Calabria and in Sardinia, where it accounts for about 90% of the G6PD Mediterranean mutations, despite the fact that gene flow between the populations of Sardinia and Southern Italy must have been limited. These data do not enable us to determine whether the two types of G6PD Mediterranean have arisen through two separate identical mutational events or through a single mutational event followed by recombination. However, the data indicate relatively little recombination over an extended region of the X chromosome and they suggest that the G6PD Mediterranean mutation is recent by comparison to the other polymorphisms investigated.

Adult↗

Polymorphism at the G6pd and 6Pgd loci in Drosophila melanogaster. IV. Genetic factors modifying enzyme activity.

Different homozygous lines of similar genotype with respect to G6pd and 6Pgd were shown to have different enzyme activities for G6PD and 6PGD. Crosses between high and low lines suggested that there were modifying genes present on the autosomes, while others were probably located on the X chromosome. Allelic variation within each electrophoretic class of G6pd and 6Pgd might, however, also have contributed to this variation. An experiment on adaptation to sodium octanoate demonstrated that in adapted flies selection for lower enzyme activity had occurred, which provided further evidence for the existence of genetic differences in activity. Furthermore, a strong positive correlation between the activities of G6PD and 6PGD was found for each genotype. Since no correlation was found between MDH and the two enzymes G6PD and 6PGD, it could be concluded that this correlation was probably rather specific for G6PD and 6PGD. Interaction between genotypes with respect to activity was also found. It was shown that the variation at 6Pgd influenced the activity of G6PD within a genotype. The data are discussed in relation to fitness differences presented in foregoing articles.

Adaptation, Physiological↗

Solution hybridization quantitation of G6PD mRNA in rat epididymal fat pads.

A solution hybridization assay is systematically characterized and used to quantitate glucose-6-phosphate dehydrogenase (G6PD) mRNA from epididymal fat pads in fasted and glucose-induced rats. G6PD mRNA and specific activity increase 9-fold and 2-fold, respectively. The 9-fold increase in G6PD synthesis reported previously (Wolfe et al. (1979) Biochem. Biophys. Res. Commun. 89, 108-115) can, therefore, be accounted for by the increase in G6PD mRNA. This solution hybridization assay is sensitive enough to quantitative levels of G6PD mRNA in total liver RNA from a fasted rat, one of the least abundant sources of this mRNA. It can, therefore, be used to answer several questions about the regulation of G6PD synthesis in rat tissues. Preliminary results suggest that the dietary regulation of G6PD mRNA in rat liver is much larger than previously reported.

Adipose Tissue↗

Prevalence of factor V Leiden and G6PD 1311 silent mutations in Dalmatian population.

BACKGROUND: Factor V Leiden has been described as a common genetic risk factor for venous thromboembolism. The geographic distribution of this abnormality varies greatly, being high in Europe and almost absent in Asia and Africa. Particularly high prevalence is observed in some Mediterranean countries, which suggests the Mediterranean origin of this mutation. Similarly, prevalence of silent mutation 1311 of the G6PD gene seems to be higher among Mediterranean populations. Since the Dalmatian population (of south Croatia) geographically belongs to the Mediterranean populations we analyzed the prevalence of FV-Leiden and silent mutation 1311 in this region. Furthermore, because the coincidence of G6PD deficiency and venous thromboembolism was described earlier, we tested a possible association of FV-Leiden and G6PD deficiency. METHODS: One hundred sixty-eight healthy blood donors and 55 G6PD deficient individuals originating from the Dalmatian region were tested for the presence of FV-Leiden mutation and silent mutation 1311. RESULTS: Prevalence of FV-Leiden among blood donors was 2.4%, while among G6PD deficient individuals it was significantly higher, 11% (p=0.011). Prevalence of silent mutation 1311 among blood donors and G6PD deficient individuals was 21 and 15%, respectively. CONCLUSIONS: Observed allele frequencies among individuals originating from the Dalmatian region is similar to the neighboring European and Mediterranean populations. Interestingly, our results indicate the association of the FV-Leiden and G6PD deficiency and warrant further studies.

Croatia↗

Evaluation of DNA damage in leukocytes of G6PD-deficient Iranian newborns (Mediterranean variant) using comet assay.

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most common inherited disease, which causes neonatal hemolytic anemia and jaundice. Recent studies of our group showed that the Mediterranean variant of this enzyme (Gd-Md) is the predominant G6PD in Iranian male infants suffering from jaundice; this variant is classified as severe G6PD deficiency. Considering the importance of G6PD reaction and its products NADPH and glutathione (GSH) against oxidative stress, we hypothesized the failure of detoxification of H(2)O(2) in G6PD-deficient white blood cells that could probably induce primary DNA damage. For the evaluation of DNA damage, we analyzed mononuclear leukocytes of 36 males suffering from the Gd-Md deficiency using alkaline single cell gel electrophoresis (SCGE) or comet assay. The level of DNA damage was compared with the level of basal DNA damage in control group represented by healthy male infant donors (of the same age group). Visual scoring was used for the evaluation of DNA damages. The results showed that the mean level of the DNA strand breakage in mononuclear leukocytes of 36 male G6PD-deficient (Gd-Md) infants was significantly higher (P < 0.001) than those observed in the normal lymphocytes. In conclusion, this investigation indicates that the mononuclear leukocytes of the Gd-Md samples may be exposed to DNA damage due to oxidative stress. This is the first report using comet assay for evaluation of DNA damage in severe G6PD deficiency samples.

Comet Assay↗