Characterization of G6PD Genotypes and Phenotypes on the Northwestern Thailand-Myanmar Border

Mutations in the glucose-6-phosphate dehydrogenase (G6PD) gene result in red blood cells with increased susceptibility to oxidative damage. Significant haemolysis can be caused by primaquine and other 8-aminoquinoline antimalarials used for the radical treatment of Plasmodium vivax malaria. The distribution and phenotypes of mutations causing G6PD deficiency in the male population of migrants and refugees in a malaria endemic region on the Thailand-Myanmar border were characterized. Blood samples for G6PD fluorescent spot test (FST), G6PD genotyping, and malaria testing were taken from 504 unrelated males of Karen and Burman ethnicities presenting to the outpatient clinics. The overall frequency of G6PD deficiency by the FST was 13.7%. Among the deficient subjects, almost 90% had the Mahidol variant (487G>A) genotype. The remaining subjects had Chinese-4 (392G>T), Viangchan (871G>A), Açores (595A>G), Seattle (844G>C) and Mediterranean (563C>T) variants. Quantification of G6PD activity was performed using a modification of the standard spectrophotometric assay on a subset of 24 samples with Mahidol, Viangchan, Seattle and Chinese-4 mutations; all samples showed a residual enzymatic activity below 10% of normal and were diagnosed correctly by the FST. Further studies are needed to characterise the haemolytic risk of using 8-aminoquinolines in patients with these genotypes.     

A New Glucose-6-Phosphate Dehydrogenase Variant, G6PD Orissa (44 Ala→Gly), is the Major Polymorphic Variant in Tribal Populations in India

Deficiency of glucose-6-phosphate dehydrogenase (G6PD) is usually found at high frequencies in areas of the world where malaria has been endemic. The frequency and genetic basis of G6PD deficiency have been studied in Africa, around the Mediterranean, and in the Far East, but little such information is available about the situation in India. To determine the extent of heterogeneity of G6PD, we have studied several different Indian populations by screening for G6PD deficiency, followed by molecular analysis of deficient alleles. The frequency of G6PD deficiency varies between 3% and 15% in different tribal and urban groups. Remarkably, a previously unreported deficient variant, G6PD Orissa (44 Ala→Gly), is responsible for most of the G6PD deficiency in tribal Indian populations but is not found in urban populations, where most of the G6PD deficiency is due to the G6PD Mediterranean (188 Ser→Phe) variant. The K of G6PD Orissa is fivefold higher than that of the normal enzyme. This may be due to the fact that the alanine residue that is replaced by glycine is part of a putative coenzyme-binding site.     

Prevalence and Molecular Identification of the Mediterranean Variant Among G6PD-Deficient Sistani and Balouch Males in Southeastern Iran

To determine the prevalence of G6PD deficiency and a Mediterranean mutation among males in southeastern Iran, we studied 1,097 Sistani and Balouch schoolboys. A questionnaire was used to collect demographic data and a history of malaria infection; blood samples were evaluated for G6PD deficiency and the G6PD Mediterranean mutation. Of the 1,097 boys screened, 175 were G6PD deficient (5.8 % of the Sistani boys and 19.3 % of the Balouch boys). The malaria survey indicated that among Balouch subjects, malaria infection was about 14 times that of Sistani subjects. Molecular characterization of G6PD-deficient samples revealed a general frequency of 85.1 % for the Mediterranean variant among all subjects (75 % among Sistani and 86.2 % among Balouch cases). The high prevalence of G6PD deficiency among Balouch populations confirms the hypothesis that the distribution of G6PD deficiency is concordant with the geographic distribution of malaria.     

Protein methylation as a marker of aspartate damage in glucose-6-phosphate dehydrogenase-deficient erythrocytes: role of oxidative stress.

The 'Mediterranean' variant of glucose-6-phosphate dehydrogenase (G6PD) deficiency is due to the C563CT point mutation, leading to replacement of Ser with Phe at position 188, resulting in acute haemolysis triggered by oxidants. Previous work has shown increased formation of altered aspartate residues in membrane proteins during cell ageing and in response to oxidative stress in normal erythrocytes. These abnormal residues are specifically recognized by the repair enzyme L-isoaspartate (d-aspartate) protein O-methyltransferase (PCMT; EC 2.1.1.77). The aim of this work was to study the possible involvement of protein aspartate damage in the mechanism linking the G6PD defect and erythrocyte injury, through oxidative stress. Patients affected by G6PD deficiency (Mediterranean variant) were selected. In situ methylation assays were performed by incubating intact erythrocytes in the presence of methyl-labelled methionine. Altered aspartate residues were detected in membrane proteins by methyl ester quantification. We present here evidence that, in G6PD-deficient erythrocytes, damaged residues are significantly increased in membrane proteins, in parallel with the decay of pyruvate kinase activity, used as a cell age marker. Erythrocytes from patients were subjected to oxidative stress in vitro, by treatment with t-butylhydroperoxide, monitored by a rise in concentration of both methaemoglobin and thiobarbituric acid-reactive substances. L-Isoaspartate residues increased dramatically in G6PD-deficient erythrocytes in response to such treatment, compared with baseline conditions. The increased susceptibility of G6PD-deficient erythrocytes to membrane protein aspartate damage in response to oxidative stress suggests the involvement of protein deamidation/isomerization in the mechanisms of cell injury and haemolysis.     

Glucose-6-phosphate dehydrogenase deficiency and infection: a study of hospitalized patients in Iran.

The Mediterranean variant of glucose-6-phosphate dehydrogenase (G6PD) is functionally deficient and found in a variety of cell types of affected individuals, including both erythocytes and neutrophils. To determine if the presence of this sex-linked gene is associated to any degree with the occurrence of severe bacterial infection, a study of hospitalized male patients in Iran was undertaken. As determined by erythrocyte assay, allele prevalence in male patients with infection was 22% vs. 12% in a patient group matched for the absence of other risk factors for infection and 6% in a second group who had additional risk factors for infection. When the control and patient groups were considered together the difference between the frequency of G6PD deficiency (10.2%) was significantly different from that found in the infected patients (p less than .05). Furthermore, the mean age of infected patients with G6PD deficiency was significantly less than that of infected patients without G6PD deficiency or non-infected control groups. These data suggest that host defenses may be altered in G6PD deficiency so that bacterial infections are more severe. Alternatively, G6PD deficiency and infection might represent concomittant risk factors which lead to hospitalization during bacterial infection. Potential mechanisms by which host defenses might be altered in G6PD deficiency are discussed.     

Heterogeneity of glucose-6-phosphate dehydrogenase deficiency in Algeria

Summary Glucose-6-phosphate dehydrogenase (G6PD) deficiency was found in 3.2% of the male population living in the urban area of Algiers. The deficient subjects originated from multiple geographic regions of Northern Algeria, with prevalence of individuals of Berber-Kabyle origin. Red blood cell G6PD was partially purified and characterized in deficient males from 17 families, and six different variants were found. Among them, only one, the Gd(-) Kabyle variant, had been previously described. It was detected in nine families. The other five variants were new: Gd(-) Laghouat (four cases), Gd(-) Blida (one case), Gd(-) Thenia (one case), Gd(-) Titteri (one case), and Gd(-) Alger (two brothers), Strikingly, the common Mediterranean variant was not found. G6PD deficiency is heterogeneous in northern Algeria where autochtonous variants seem to prevail. The Kabyle variant may be common in this country.     

Galactitol accumulation by glucose-6-phosphate deficient fibroblasts: a cellular model for resistance to the complications of diabetes mellitus

When incubated in high galactose media, fibroblasts from individuals with the severe (Mediterranean) variety of glucose-6-phosphate dehydrogenase (G6PD) deficiency accumulate significantly less galactitol than do fibroblasts from matched control subjects. The effect is not observed in fibroblasts from black subjects with the more common, and milder, A- variant of G6PD deficiency. Since aldose reductase and sorbitol dehydrogenase activities in experimental and control fibroblasts are identical, the effect is most likely due to the substantial reduction in NADPH levels in severely G6PD-deficient cells. Sorbitol does not accumulate either in control or in G6PD deficient fibroblasts incubated in high glucose medium, most likely because of the action of sorbitol dehydrogenase, and the presence of a carrier-mediated glucose transport system in the cell membrane which limits the concentration of glucose that can accumulate in these cells.     

Glucose-dependent Protection by Dietary Selenium against Haemolysis of Rat Erythrocytes <Emphasis Type="Italic">in vitro</Emphasis>

THE occurrence in man of drug-induced haemolysis in glucose-6-phosphate dehydrogenase (G6PD) deficient erythrocytes¹ suggested the possibility of an analogy to the haemolysis which occurs in vitamin E deficient red blood cells. Cohen and Hochstein² have shown that haemolysis in G6PD deficient cells is associated with the inability of the cell to generate adequate reduced glutathione (GSH) through GSSG reductase because of the impaired generation of NADPH. Moreover, there is evidence that glucose protects red blood cells from haemolysis by its ability to provide NADPH through G6PD which subsequently generates GSH³. The G6PD deficient cell, however, cannot maintain an adequate concentration of GSH in the cell, even in the presence of glucose⁴, whereas the normal cell can maintain a normal concentration of GSH in the presence of glucose, preserving the integrity of the red blood cell. Vitamin E protects red blood cells from haemolysis whether supplied in vivo or in vitro and its effect has usually been demonstrated without glucose in the incubation medium. Although selenium prevents many of the same deficiency symptoms as vitamin E, it has not been uniformly effective in preventing the in vitro haemolysis of red blood cells. If a protective action of selenium against haemolysis were dependent on the presence of GSH, or if selenium were involved in the generation of GSH, selenium would not be expected to prevent haemolysis unless glucose was present in the incubation medium to provide a constant source of NADPH for the generation of GSH from GSSG through GSSG reductase (Fig. 1).     

Genetic heterogeneity at the glucose-6-phosphate dehydrogenase locus in southern Italy: a study on a population from the Matera district

Summary Glucose-6-phosphate dehydrogenase (G6PD) has been analyzed by gel electrophoresis and by quantitative assay in an unselected sample of 1524 schoolboys from the province of Matera (Lucania) in southern Italy. We have identified 43 subjects with a G6PD variant. Of these, 31 had severe G6PD deficiency, nine had mild to moderate deficiency, and three had a non-deficient electrophoretic variant. The overall rate of G6PD deficiency was 2.6%. The frequency of G6PD deficiency, ranging from 7.2% on the Ionian Coast to zero on the eastern side of the Lucanian Apennines, appears to be inversely related to the distance of each town examined from the Ionian Coast, suggesting that this geographic distribution may reflect, at least in part, gene flow from Greek settlers. Biochemical characterization has shown that most of the G6PD deficiency in this population is accounted for by G6PD Mediterranean. In addition, we have found several examples of two other known polymorphic variants (G6PD Cagliari and G6PD A^–): three new polymorphic variants. G6PD Metaponto (class III), G6PD Montalbano (class III), and G6PD Pisticci (class IV); and two sporadic variants, G6PD Tursi (class III) and G6PD Ferrandina (class II). These data provide further evidence for the marked genetic heterogeneity of G6PD deficiency within a relatively narrow geographic-area and they prove the presence in the Italian peninsula of a sene (Gd ^A–) regarded as characteristically African.     

Haemolytic anaemia after cisplatin treatment.

Normochromic or normocytic anaemia is a common side effect of treatment with cisplatin. Two patients treated with cisplatin 100 mg/m2 in combination with vinblastine, bleomycin, and actinomycin D developed haemolytic anaemia. Neither patient had evidence of haemolysis before treatment, and in both cases severe haemolytic anaemia developed after several courses of cisplatin and when the cancer had regressed almost completely. The importance of haemolysis in the development of anaemia after cisplatin treatment has not been investigated fully and further studies are needed.     

A new glucose 6-phosphate dehydrogenase variant (G6PD Thessaloniki) in a patient with idiopathic myelofibrosis

A new deficient glucose 6-phosphate dehydrogenase (G6PD) variant, G6PD Thessaloniki, which was found in the red blood cells of a 70-year-old woman who had idiopathic myelofibrosis, is described. G6PD Thessaloniki had a low Michaelis constant (Km) for G6P (20 microM), high Km for NADP (10.1 microM), normal pH optimum, reduced heat stability, decreased electrophoretic mobility (96-98% of the normal), increased 2-deoxy-G6P and decreased galactose 6-phosphate utilization. Several other enzymatic activities measured in the patient's red blood cells were normal. Studies of red blood cell survival and glucose utilization gave evidence of haemolysis caused by defective glucose utilization by the pentose phosphate pathway. The only son of the patient had normal G6PD in his red blood cells. In an attempt to investigate the origin of G6PD Thessaloniki, heat stability tests of G6PD extracted from the patient's skin have been performed.     

Serum ferritin in patients with various haemolytic disorders.

174 serum ferritin assays in 121 patients with various haemolytic disorders have been performed. The mean serum ferritin levels were significantly increased in all these disorders in contrast to healthy controls. The highest serum ferritin levels were found in pyruvate kinase (PK) deficiency, moderate increase was observed in hereditary sphaerocytosis (HS) and in autoimmune haemolytic anaemia (AIHA) with massive haemolysis and in glucose-6-phosphate dehydrogenase (G-6-PD) deficiency. Mild elevation of serum ferritin levels was depicted in paroxysmal nocturnal haemoglobinuria (PNH), in beta thalassaemia minor and in other types of haemoglobinopathies. The range of values was associated with a degree of haemolysis and its relation to duration of the disease was not apparent in most cases. Highly significant differences between serum ferritin levels in splenectomized and non-splenectomized patients with HS and between serum ferritin levels in patients with AIHA with massive haemolysis or in remission were found. As compared to normal controls, significant increase of serum ferritin levels was observed even in patients with AIHA in remission or in splenectomized patients with HS. In two patients with PK deficiency the levels exceeding 2,000 micrograms/l indicated manifest iron overload. A reliability of serum ferritin assay as an index of iron stores in haemolytic disorders has been discussed.     

Human glucose-6-phosphate dehydrogenase: the crystal structure reveals a structural NADP(+) molecule and provides insights into enzyme deficiency

BACKGROUND: Glucose-6-phosphate dehydrogenase (G6PD) catalyses the first committed step in the pentose phosphate pathway; the generation of NADPH by this enzyme is essential for protection against oxidative stress. The human enzyme is in a dimer<-->tetramer equilibrium and its stability is dependent on NADP(+) concentration. G6PD deficiency results from many different point mutations in the X-linked gene encoding G6PD and is the most common human enzymopathy. Severe deficiency causes chronic non-spherocytic haemolytic anaemia; the usual symptoms are neonatal jaundice, favism and haemolytic anaemia. RESULTS: We have determined the first crystal structure of a human G6PD (the mutant Canton, Arg459-->Leu) at 3 A resolution. The tetramer is a dimer of dimers. Despite very similar dimer topology, there are two major differences from G6PD of Leuconostoc mesenteroides: a structural NADP(+) molecule, close to the dimer interface but integral to the subunit, is visible in all subunits of the human enzyme; and an intrasubunit disulphide bond tethers the otherwise disordered N-terminal segment. The few dimer-dimer contacts making the tetramer are charge-charge interactions. CONCLUSIONS: The importance of NADP(+) for stability is explained by the structural NADP(+) site, which is not conserved in prokaryotes. The structure shows that point mutations causing severe deficiency predominate close to the structural NADP(+) and the dimer interface, primarily affecting the stability of the molecule. They also indicate that a stable dimer is essential to retain activity in vivo. As there is an absolute requirement for some G6PD activity, residues essential for coenzyme or substrate binding are rarely modified.     

Catalase deficiency may complicate urate oxidase (rasburicase) therapy

Patients with low (inherited and acquired) catalase activities who are treated with infusion of uric acid oxidase because they are at risk of tumour lysis syndrome may experience very high concentrations of hydrogen peroxide. They may suffer from methemoglobinaemia and haemolytic anaemia which may be attributed either to deficiency of glucose-6-phosphate dehydrogenase or to other unknown circumstances. Data have not been reported from catalase deficient patients who were treated with uric acid oxidase. It may be hypothesized that their decreased blood catalase could lead to the increased concentration of hydrogen peroxide which may cause haemolysis and formation of methemoglobin. Blood catalase activity should be measured for patients at risk of tumour lysis syndrome prior to uric acid oxidase treatment.     

Catalase deficiency may complicate urate oxidase (rasburicase) therapy

Patients with low (inherited and acquired) catalase activities who are treated with infusion of uric acid oxidase because they are at risk of tumour lysis syndrome may experience very high concentrations of hydrogen peroxide. They may suffer from methemoglobinaemia and haemolytic anaemia which may be attributed either to deficiency of glucose-6-phosphate dehydrogenase or to other unknown circumstances. Data have not been reported from catalase deficient patients who were treated with uric acid oxidase. It may be hypothesized that their decreased blood catalase could lead to the increased concentration of hydrogen peroxide which may cause haemolysis and formation of methemoglobin. Blood catalase activity should be measured for patients at risk of tumour lysis syndrome prior to uric acid oxidase treatment.     

At least five polymorphic mutants account for the prevalence of glucose-6-phosphate dehydrogenase deficiency in Algeria

The electrophoretic mobility and level of enzyme activity of glucose-6-phosphate dehydrogenase (G6PD) was established in 100 unrelated Algerian males with G6PD deficiency. DNA from these subjects was analysed for the presence of certain known G6PD mutations by the appropriate restriction enzyme digestion of fragments amplified by the polymerase chain reaction. Where the mutation could not be identified in this way, the samples were subjected to single-strand conformation polymorphism analysis and abnormal fragments were sequenced. In this way, eight different mutations have been identified, of which five are polymorphic and account for 92% of the samples. The most common variants are G6PD A-(46%) and G6PD Mediterranean (23%), both of which were associated with favism. A new polymorphic variant, G6PD Aures, has been identified during the course of this study, whereas another, G6PD Santamaria, has now been established as a polymorphic variant (11%). Thus, G6PD deficiency in Algeria is heterogeneous, suggesting that there has been significant gene flow, both from sub-Saharan Africa and from other parts of the Mediterranean.     

Genetic polymorphism of G6PD in a Bulgarian population

Summary Considerable genetic heterogeneity in G6PD was found in the Bulgarian population-14 G6PD variants isolated from 117 hemizygous carriers of G6PD deficiency. Of these, G6PD Mediterranean type was a polymorphic variant and G6PD Corinth occured with high frequency. Two new variants were identified-G6PD Rudosem and G6PD Nedelino. In a selected group of 78 subjects with clinical manifestations, four variants were established: G6PD Mediterranian, G6PD Corinth, G6PD Seattle and G6PD Ohut II.     

Red Cell Survival after Heterograft Valve Surgery

Intravascular haemolysis was studied in 24 patients three to nine months after calf or pig valve heterografts had been inserted for severe valvular heart disease. No patient had haemolytic anaemia. In five of the 24 patients there was subclinical haemolysis, and in these five the haemolysis appeared to be related to residual aortic regurgitation or to the presence of other foreign material such as a Dacron aortic graft. The extent of postoperative haemolysis in these five patients was comparable to that observed preoperatively in patients with valvular heart disease.The results support the belief that, in contrast to artificial valve prostheses, heterograft valves behave similarly to human valves as regards haemolysis.     

Origin and spread of the glucose-6-phosphate dehydrogenase variant (G6PD-Mediterranean) in the Middle East.

A common glucose-6-phosphate dehydrogenase (G6PD) variant characterized by severe enzyme deficiency and B-like electrophoretic mobility is called "G6PD-Mediterranean" because it is found in different populations around the Mediterranean Sea. Sequence analysis of Italian subjects has revealed that the molecular basis of G6PD-Mediterranean is a single C-T transition at nucleotide position 563, causing a serine phenylalanine replacement at amino acid position 188. Most G6PD-Mediterranean subjects also have a silent C-T transition (without amino acid replacement) at nucleotide position 1311. Twenty-one unrelated individuals from Saudi Arabia, Iraq, Iran, Jordan, Lebanon, and Israel with both severe G6PD deficiency and B-like electrophoretic mobility were tested for both mutations by using amplification followed by digestion with appropriate restriction enzymes. All but one had the 563 mutation, and, of these, all but one had the 1311 mutation. Another 24 unrelated Middle Eastern individuals with normal G6PD activity or not known to be G6PD deficient were similarly tested. Four had the silent mutation at position 1311 in the absence of the deficiency mutation at position 563. We conclude that (1) the large majority of Middle Eastern subjects with the G6PD-Mediterranean phenotype have the same mutation found in Italy, (2) the silent mutation is an independent polymorphism in the Middle East, with a frequency of about .13, and (3) the mutation leading to the G6PD-Mediterranean deficiency has probably arisen on a chromosome that already carried the silent mutation.     

The prevalence of factor V Leiden,prothrombin G20210A and methylenetetrahydrofolate reductase polymorphism C677T among G6PD deficient individuals from Western Iran

It has been suggested that the allele frequency of thrombophilic mutations is affected by glucose-6-phosphate dehydrogenase (G6PD) deficiency. The prevalence of thrombophilic mutations were studied in sixty G6PD deficient individuals including 57 males and three females with the mean age of 15 ± 3.08 and 110 age and sex matched healthy individuals consisted of 95 males and 15 females with the mean age of 16.19 ± 2.17 from the Kermanshah Province of Iran. Using a combination of PCR-RFLP technique, single strand conformation polymorphism (SSCP) analysis and DNA sequencing polymorphic G6PD mutations were identified. The factor V Leiden, prothrombin G20210A and methylenetetrahydrofolate reductase (MTHFR) C677T were detected by PCR-RFLP method using MnlI, HindIII and HinfI restriction enzymes, respectively. Three mutations, G6PD Mediterranean, G6PD Chatham and G6PD Cosenza were identified in 60 G6PD deficient individuals with highest prevalence of G6PD Mediterranean (91.6%). In G6PD deficient individuals the prevalence of factor V Leiden tended to be higher (5%) compared to healthy individuals (2.7%). The prevalence of prothrombin G20210A mutation in G6PD deficient individuals was 1.7%. However, in normal subjects the prevalence of this mutation was 2.7%. The frequency of T allele in G6PD deficient individuals were insignificantly higher (29.16%) than those in healthy individuals (26.8%). Our finding indicates that the prevalence of factor V Leiden, prothrombin G20210A and MTHFR C677T in G6PD deficient individuals is not statistically different compared to normal subjects and G6PD deficiency is not associated with these thrombophilic mutations in Western Iran.