Two new variants of glucose-6-phosphate dehydrogenase associated with hereditary non-spherocytic hemolytic anemia: G6PD Wayne and G6PD Huron

Two new deficient variants of glucose-6-phosphate dehydrogenase (G6PD) causing hereditary nonspherocytic hemolytic anemia (HNSHA) are described. Both of these are unique and they have been named G6PD Wayne and G6PD Huron. Patients with G6PD Wayne underwent splenectomy and no objective improvement was noted. The patients with G6PD Huron were under medical observation for a considerable period of time without the diagnosis of G6PD deficiency being entertained because the family was of Northern European origin. Since sporadic variants of G6PD causing HNSHA show no special racial predilection, the diagnosis of G6PD deficiency should always be considered in patients with this syndrome.     

Two new glucose-6 phosphate dehydrogenase (G6PD) variants associated with hemolytic anemia: G6PD Amman-1 and G6PD Amman-2

Two glucose-6-phosphate dehydrogenase (G6PD) variants were investigated. G6PD Amman-1 was partially purified from the red cells of a patient suffering from recurrent jaundice and spontaneous episodic attacks of severe hemolysis in the absence of oxidant drugs, infection, or fava beans. The enzymatic characteristics of G6PD Amman-1 were markedly reduced activity, fast eletrophoretic mobility, slightly increased km for NADP, normal km for G-6-P, normal heat stability, normal utilization of substrate analogues 2-deoxy G-6-P and deamino-NADP, and a monophasic pH curve with a peak at 8.5 to 9.3. The second variant, G6PD Amman-2, was partially purified from the red cells of a patient suffering from recurrent jaundice with episodic mild hemolysis caused by infection or unknown factors. G6PD Amman-2 characteristics were severely reduced activity, slow electrophoretic mobility, normal km for NADP, decreased km for G-6-P, decreased heat stability, increased utilization of substrate analogues, and a monophasic pH curve with a narrow peak at pH 9.5. The red cell level of reduced glutathione was markedly decreased with twofold increase in the activity of glutathione reductase in the patient with G6PD Amman-2.     

Reduced prevalence of Plasmodium falciparum infection and of concomitant anaemia in pregnant women with heterozygous G6PD deficiency

Glucose-6-phosphate dehydrogenase (G6PD) deficiency confers protection against malaria in children, yet its role in malaria in pregnancy is unknown. In a cross-sectional study among 529 pregnant Ghanaian women, Plasmodium falciparum infection, anaemia and G6PD genotypes were assessed. Of these, 30.4% were heterozygous and 2.6% were homozygous for G6PD deficiency. The prevalence of P. falciparum infection decreased from 66% in G6PD-normal women to 58% in heterozygotes, and to 50% in individuals with homozygous G6PD deficiency (Chi2(trend) = 4.4, P = 0.04). Multivariate analysis revealed that in multigravid women but not in primigravidae, heterozygous G6PD deficiency was associated with a reduced risk of P. falciparum infection (Odds ratio (OR), 0.6; 95% confidence interval (95% CI), [0.4-0.9]). This protection against infection was limited to the third trimenon of pregnancy. In addition, heterozygous G6PD deficiency was associated with a reduced risk of anaemia among infected multigravidae (OR, 0.5 [0.3-1.0]). Pregnancy is a period of high vulnerability to malaria. The results of this study provide evidence for protection against malaria in pregnancy caused by heterozygous G6PD deficiency. This advantage, even if confined to multigravid women, may contribute to the selection of G6PD variants in malaria-endemic regions.     

贵州江口土家族男性葡萄糖-6-磷酸脱氢酶缺陷症的基因频率调查

目的调查贵州省江口土家族男性葡萄糖-6-磷酸脱氢酶(G6PD)缺陷症的基因频率。方法2002年10—11月随机选取227名江口当地土家族男性居民,采用四氮唑蓝(NBT)纸片定性法初筛G6PD缺陷症,G6PD/6PGD比值法定量确诊。结果对贵州省江口县227名土家族男性进行筛查,共检出17例G6PD缺陷阳性,其基因频率为0·0749。结论通过对贵州土家族G6PD缺乏症基因频率的调查和分析,初步了解了贵州省土家族G6PD缺乏症的分布特征。为该地区预防该疾病、指导临床、提高少数民族的素质及研究该民族起源提供了一定的依据。     

贵州江口土家族男性葡萄糖-6-磷酸脱氢酶缺陷症的基因频率调查

目的 调查贵州省江口土家族男性葡萄糖-6-磷酸脱氢酶（G6PD）缺陷症的基因频率。方法 2002年10-11月随机选取227名江口当地土家族男性居民，采用四氮唑蓝（NBT）纸片定性法初筛G6PD缺陷症。G6PD／6PGD比值法定量确诊。结果 对贵州省江口县227名土家族男性进行筛查，共检出17例G6PD缺陷阳性。其基因频率为0．0749。结论 通过对贵州土家族G6PD缺乏症基因频率的调查和分析，初步了解了贵州省土家族G6PD缺乏症的分布特征。为该地区预防该疾病、指导临床、提高少数民族的素质及研究该民族起源提供了一定的依据。     

Molecular genetics of glucose-6-phosphate dehydrogenase (G6PD) deficiency in Spain: identification of two new point mutations in the G6PD gene

Summary .In order to explore the nature of glucose-6-phosphate dehydrogenase (G6PD) deficiency in Spain, we have analysed the G6PD gene in 11 unrelated Spanish G6PD-deficient males and their relatives by using the polymerase chain reaction and single-strand conformation polymorphism (PCR-SSCP) analysis combined with a direct PCR-sequencing procedure and PCR-restriction enzyme (RE) analysis. We have identified eight different missense mutations, six of which have been reported in previously described G6PD variants. In nine patients who had presented with acute favism we found the following mutations: G6PD A_^376G–202A (four cases)| G6PD Union^1360T (two cases), G6PD Mediterranean^563T, (one case) and G6PD Aures^143c (one case). In the remaining patient a novel A to G transition was found at nucleotide position 209 which has not been reported in any other ethnic group. This mutation results in a (70) Tyr to Cys substitution and the resulting G6PD variant was biochemically characterized and designated as G6PD Murcia. This new mutation creates a Bsp 12861 recognition site which enabled us to rapidly detect it by PCRRE analysis. In two patients with chronic non-spherocytic haemolytic anaemia (CNSHA) we found the underlying genetic defects, as had been noted previously, to be located within a cluster of mutations in exon 10. One of them had the T to C transition at nucleotide 1153, causing a (3 8 5) Cys to Arg substitution, previously described in G6PD Tomah. The other, previously reported as having a variant called G6PD Clinic, has a G to A transition at nucleotide 1215 that produces a (405) Met to He substitution, thus confirming that G6PD Clinic is a new class I variant.     

Genetic variants causing G6PD deficiency: Clinical and biochemical data support new WHO classification

Glucose-6-phosphate dehydrogenase (G6PD) deficiency in erythrocytes causes acute haemolytic anaemia upon exposure to fava beans, drugs, or infection; and it predisposes to neonatal jaundice. The polymorphism of the X-linked G6PD gene has been studied extensively: allele frequencies of up to 25% of different G6PD deficient variants are known in many populations; variants that cause chronic non-spherocytic haemolytic anaemia (CNSHA) are instead all rare. WHO recommends G6PD testing to guide 8-aminoquinolines administration to prevent relapse of Plasmodium vivax infection. From a literature review focused on polymorphic G6PD variants we have retrieved G6PD activity values of 2291 males, and for the mean residual red cell G6PD activity of 16 common variants we have obtained reliable estimates, that range from 1.9% to 33%. There is variation in different datasets: for most variants most G6PD deficient males have a G6PD activity below 30% of normal. There is a direct relationship between residual G6PD activity and substrate affinity (K_m^G6P), suggesting a mechanism whereby polymorphic G6PD deficient variants do not entail CNSHA. Extensive overlap in G6PD activity values of individuals with different variants, and no clustering of mean values above or below 10% support the merger of class II and class III variants.     

Clinical and haematological consequences of recurrent G6PD mutations and a single new mutation causing chronic nonspherocytic haemolytic anaemia

We have determined the causative mutation in 12 cases of glucose-6-phosphate dehydrogenase deficiency associated with chronic non-spherocytic haemolytic anaemia. In 11 of them the mutation we found had been previously reported in unrelated individuals. These mutations comprise seven different missense mutations and a 24 base pair deletion, G6PD Nara, previously found in a Japanese boy. Repeated findings of the same mutations suggests that a limited number of amino acid changes can produce the CNSHA phenotype and be compatible with normal development. The one new mutation we have found, G6PD Serres, is 1082 C → T causing a 361 Ala → Val substitution in the dimer interface where most other severe G6PD mutations are found. Now that several patients with the same mutation have been reported we can compare the resulting clinical phenotypes. For each mutation we find a reasonably consistent clinical picture, ranging from mild (G6PD Clinic) through moderate (G6PD Nashville) to severe (G6PD Beverly Hills and G6PD Nara).     

Characterization of a new glucose-6-phosphate dehydrogenase variant: G6PD Central City

Glucose-6-phosphate-dehydrogenase deficiency is the most common disease-producing enzyme deficiency in man. This paper describes a new glucose-6-phosphate-dehydrogenase variant discovered during the evaluation of an episode of acute hemolytic anemia in a 62-year-old black male, which was temporally related to the ingestion of Tolbutamide. The hemolysis resolved within 10 days despite continuation of Tolbutamide. The erythrocyte glucose-6-phosphate-dehydrogenase activity was significantly decreased, and its electrophoretic mobility was indistinguishable from wild type enzyme, though faster on starch gel with tris, borate, and phosphate buffers. The enzyme had a biphasic pH optimum reduced Km for G-6-P and NADP, decreased utilization of deamino-NADP, and reduced Ki for NADPH. Because the kinetic properties of this enzyme were unique, we have designated it as G6PD Central City.     

Molecular heterogeneity of G6PD deficiency in an Amazonian population and description of four new variants

To characterize the molecular variation in the glucose-6-phosphate dehydrogenase gene (G6PD), 196 asymptomatic and unrelated male G6PD-deficient blood donors from Belém, an Amazonian metropolis (Brazil), were analyzed. This deficiency was detected by horizontal agarose gel electrophoresis and quantitative spectrophotometric assay for enzyme activity. The mutations were searched by PCR/RFLP, SSCP, and direct DNA sequencing. The most frequent G6PD variant was the widespread and common G6PD A- (202G --> A, 376A --> G) observed in 161 subjects (82.1%). Besides this, we found another form of G6PD A- (968T --> C, 376A --> G) in 14 (7.1%) individuals, G6PD Seattle (844G --> C) in 4.6%, G6PD Santamaria (542A --> T, 376A --> G) in 2.5%, and G6PD Tokyo (1246G --> A) in one blood donor. Four novel variants were also identified: G6PD Belém (409C --> T; Pro137His), G6PD Ananindeua (376A --> G, 871G --> A; Asn126Asp, Val291Met), G6PD Crispim with four point mutations (375G --> T, 379G --> T, 383T --> C, and 384C --> T) leading to three amino acid substitutions (Met125Ile, Ala127Ser, and Leu128Pro), and G6PD Amazonia (185C --> A; Pro62His). The reported frequencies do not reflect the real values for blood donors from Belém, since an excess of individuals with "non A-" phenotype was included in this study to enhance the probability to find rare variants. Haplotype analyses were carried out for the less common G6PD variants identified in our study using PCR/RFLP for five polymorphic sites (FokI, PvuII, PstI, BclI, NlaIII). G6PD Crispim and G6PD Amazonia variants presented the most common haplotype found in G6PD B (- - + - -). G6PD Belém presented two haplotypes (- - + + +, - + + + +) and G6PD Ananindeua was found with the + - + - + haplotype. The reported heterogeneity probably is due to the great miscegenation, characteristic of the population of the Amazonian region, besides the apparently common occurrence of recurrent mutations in the G6PD gene.     

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.     

The effect of BCNU and adriamycin on normal and G6PD deficient erythrocytes

In cell free systems Adriamycin induces oxygen radicals. We have shown previously that Adriamycin generates peroxide in human erythrocytes. BCNU, by inhibiting glutathione reductase, interferes with the major erythrocyte pathway to degrade peroxide. In this investigation we looked at interactions of these drugs with normal and abnormal erythrocytes. In G6PD-deficient erythrocytes Adriamycin posed a significant oxidant stress as demonstrated by hexose monophosphate shunt (HMPS) activity, hydrogen peroxide (H2O2) production, and glutathione depletion. At similar molar concentrations Adriamycin was a stronger oxidant than acetylphenylhydrazine. BCNU=treated normal erythrocytes showed an enhanced susceptibility to oxidant stress as demonstrated by a lack of HMPS response to H2O2 and glutathione depletion during incubations with Adriamycin. The HMPS shunt of BCNU treated RBC was intact as shown by their nearly normal response to methylene blue stimulation. These BCNU studies also demonstrated the inability of H2O2 to react directly with NADPH. In conclusion Adriamycin poses a potent oxident stress to G6PD-deficient erythrocytes. BCNU promotes enhanced susceptibility of normal RBC to oxidant stress and BCNU can act as a probe to define drug interactions with the HMPS. These studies add to a growing body of evidence postulating the importance of oxygen radicals in the therapeutic and/or effects of Adriamycin.     

NBT纸片定性法与G6PD/6PGD比值法在大样本G6PD缺陷症筛查中的联合应用

目的：探讨联合应用葡萄糖-6-磷酸脱氢酶（G6PD）四氮唑蓝（NBT）纸片定性法与G6PD／6PGD比值定量法在大样本筛查中的可行性。方法：用NBT纸片定性法对501例贵州省江口县土家族、525例从江县侗族、586例荔波县瑶族共1612例成人进行定性初筛，再用G6PD／6PGD比值法对初筛阳性样本定量复查。结果：NBT纸片定性法共初筛出G6PD缺陷患者129例，G6PD／G6PD比值法确诊G6PD缺陷123例，2种方法的符合率高达95．35％。结论：对大样本G6PD缺陷症的筛查，先用NBT纸片定性法进行初筛，再用G6PD／6PGD比值法复查确诊，2法联合应用可以提高G6PD缺陷症检出率和节约大量经费和时间。     

G6PD (AC)n and (CTT)n microsatellites in Mexican Mestizos with common G6PD African variants

Genotyping for the G6PD (AC)n and (CTT)n microsatellites in a sample of 58 Mexican Mestizos with common G6PD African variants was carried out. The second mutation that defines to the variants G6PD A(-202A/376G), G6PD Santamaria(376G/542T) and G6PD A(-376G/968C) very probably occurred on G6PD A(376G) chromosomes with the compound haplotypes, intragenic silent polymorphisms and microsatellites, Pvu-II/Pst-I/Bcl-I/Nla-III/(AC)n/(CTT)n: +/+/-/+/166 bp/195 bp, -/+/-/+/166 bp/201 bp, and -/+/-/+/166 bp/204 bp respectively. The structure of the repeat sequences for the AC-166 bp allele in the 3 variants was (TA)5(AA)1(TA)9(CA)10 whereas the repeat sequences for the CTT-195 bp, CTT-201 bp and CTT-204 bp alleles were (CTT)11(ATT)6, (CTT)7(ATT)12 and (CTT)7(ATT)13 in the first, second and third variants respectively. Genotyping for the G6PD microsatellites can be a useful tool with several applications.     

Safety of the combination of chloroquine and methylene blue in healthy adult men with G6PD deficiency from rural Burkina Faso

New drug combinations against falciparum malaria which are both effective and affordable for Sub-Saharan African populations are urgently needed. The combination of the well-known drugs chloroquine (CQ) and methylene blue (MB) is such a promising new regimen. However, there is some concern that MB could cause development of haemolysis in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency, a condition which is prevalent in malaria-endemic regions. Against this background, 74 G6PD-deficient but otherwise healthy adult men were given a 3-day oral regimen of a total of 1500 mg CQ and 780 mg MB in the District Hospital of Nouna in north-western Burkina Faso. Haemolysis did not occur, haemoglobin levels remained stable or even rose in the study participants, and the drug regimen was well tolerated. Therefore, standard dosages of MB appear to be safe in G6PD-deficient African populations with predominantly class III G6PD deficiency.     

Two new mutations of the glucose-6-phospate 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.     

The prevalence of G6PD deficiency in blood transfusion recipients

G6PD deficiency is the most common metabolic disorder of red blood cells, involving about 35 million people worldwide. Tropical and subtropical regions in the eastern hemisphere have the highest prevalence, up to 35% in some areas. The prevalence varies in different parts of the world. According to WHO, there is a 10–14.9% prevalence of G6PD deficiency in Iran. With this high prevalence, blood products are not still checked for G6PD deficiency. So, they may be used for transfusion in neonates with jaundice or for patients using oxidants.

In this cross-sectional study, we have observed the effects of using this kind of blood in patients receiving blood in the Pediatric and Neonatology Departments of Imam Sajjad's Hospital in Yasuj. Samples were taken from 261 blood bags used for transfusion or exchange, and examined by spot fluorescence for G6PD deficiency. All of the patients receiving blood were examined for hemoglobin, hematocrit, and bilirubin before and after transfusion. They were also examined for hemoglobinuria, factors involved in hemolysis due to G6PD deficiency, and oxidants.

Results: From the 261 blood transfusions, 37 (14.17%) blood bags had G6PD deficiency. About 81 % of these transfusion recipients had at least one risk factor for hemolysis. The complications associated with receiving these red cells were: insufficient rise in hemoglobin (55.9%), hemoglobinuria (35.3%) and rise in bilirubin (8.8%), which were significantly higher than the control group.

Conclusion: Considering the high prevalence and complications of transfusing G6PD deficient blood to high risk patients, it is recommended that in the form used for requesting blood products, there should be a place for checking G6PD enzyme so that the physician requesting blood could request the test to be done, depending on the risk factors.