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Prognosis of hemolytic anemia in G6PD- subjects. Multifactorial cluster analysis of biochemical characteristics of red cell age groups.

Individual susceptibility of 10 G6PD- hemizygotes to oxidative hemolytic agents was tested on the basis of multifactorial cluster analysis of biochemical indices of erythrocyte populations; the indices related to G6PD activity and glucose metabolism were analyzed under physiological and oxidative stress conditions in very young, exactly adult and very old red cell suspensions. Biochemical images of G6PD- erythrocytes were obtained and compared with the donor (7 subjects) biochemical image on a IBM-PC computer according to a special "taxon" program. As a result, a stable subdivision of 10 Gd- biochemical images into 5 taxons was formed; each taxon included G6PD subjects with a certain form of clinical appearance of G6PD deficiency. Multifactorial cluster analysis of biochemical data on the erythrocyte population allows a clinical prognosis for G6PD- subjects.

Anemia, Hemolytic↗

Erythrocyte membrane ATPase activity of G6PD-deficient individuals and the effect of primaquine metabolite(s) on membrane ATPase enzymes.

Erythrocyte membrane Na+/K+, Ca2+/Mg2+ and Mg2+ ATPase activities in addition to the calmodulin-activated Ca2+/Mg2+ ATPase enzyme were measured in both G6PD-deficient and normal individuals. Although all three membrane ATPase activities were somewhat higher in the G6PD-deficient erythrocytes, only activated Ca2+/Mg2+ ATPase activity was significantly increased. The effect of primaquine on the membrane ATPases was also compared with other ATPase inhibitors. Primaquine was ineffective on erythrocyte membrane ATPase in-vitro. However, sera containing primaquine metabolite(s) were inhibitory to Ca2+/Mg2+ and Mg2+ ATPase systems of only G6PD-deficient erythrocytes. Other ATPase inhibitors showed a similar inhibitory effect in G6PD-deficient and normal erythrocytes, indicating a specific influence of primaquine on ATPase system in G6PD deficiency. It is suggested that this effect of primaquine may be an additional factor for haemolysis observed in the people with GdB- type of G6PD deficiency among the Mediterranean populations.

Adenosine Triphosphatases↗

G6PD San Francisco: a new variant of glucose-6-phosphate dehydrogenase associated with congenital nonspherocytic hemolytic anemia.

Congenital nonspherocytic hemolytic anemia in an adult male of Scandinavian ancestry was associated with virtual absence of G6PD activity in red cells. Characterization of G6PD purified from leukocytes using standard WHO techniques revealed diminished electrophoretic mobility, marked lability on heating at 46 degrees C, normal pH optimum and utilization of alternate substrates (2-deoxy G6P, D-amino NADP), elevated Km NADP, and striking susceptibility to NADPH inhibition. The variant G6PD, which appears to be unique, has been designated G6PD San Francisco. An unusual feature of the variant enzyme, susceptibility to inactivation by brief periods of dialysis, could be prevented by addition of 200 microM NADP to the dialysis solution. In red cells, where G6PD activity was essentially absent, regeneration of reduced glutathione was totally curtailed in vitro, while in leukocytes, where residual G6PD activity was approximately 60% of normal, hexose monophosphate shunt activity, oxygen consumption during phagocytosis, and bacterial killing were unimpaired. Thus, instability of the variant enzyme rather than its unfavorable kinetics appeared to be an important determinant of abnormal cell function.

Adult↗

G6PD-deficiency: a potential high-risk group to copper and chlorite ingestion.

Although humans may accept fairly large amounts of orally ingested copper (0.25 to 1.0 gm) without visible harmful effects, patients with Wilson's disease, and persons with G6PD deficiency may represent persons at unusual risk to hemolytic anemia from ingestion of Cu(II). This study reports that in vitro exposure of G6PD deficient red blood cells to copper produced marked elevations of methemoglobin and decreases in GSH when compared with normal red cells. Chlorite, a by-product of chlorine dioxide disinfection of water, produced decreases in GSH and G6PD activity, while increasing methemoglobin levels markedly over red cells with normal G6PD activity. The combined action of chlorite and copper was additive in producing increased levels of hemoglobin and decreases in levels of GSH and G6PD deficient cells. The combined ingestion of copper and chlorite may represent an increased risk to persons with G6PD deficiency.

Adult↗

[G6PD gene mutations in Guangxi, China].

OBJECTIVE: Fifty-six G6PD-deficient male individuals of the Guangxi origin were investigated at the molecular level to understand the basis of G6PD deficiency. METHODS: PCR amplified the exons 2,5,6,7,8, 10,11,12 and 13 of the G6PD gene respectively, combined with ASO dot blot hybridization and restriction enzymes digestion methods to screen 10 common Chinese G6PD mutations. RESULTS: Six mutations were detected, namely cDNA1376(G-->T)(25.0%), cDNA1388(G-->A)(16.1%), cDNA95(A-->G)(19.8%), cDNA592 (C-->T)(7.1%), cDNA1024(C-->T)(1.8%) and cDNA392(G-->T) (1.8%). The unknown mutations accounted for 28.6%. cDNA1311(C-->T),cDNA1360(C-->T),cDNA835(A-->T), cDNA493(A-->G) and cDNA487(G-->A) were not discovered among the cases. CONCLUSION: The findings may provide some useful informations for physician scientists to get insight into the pathogenesis of G6PD deficiency so as to improve clinical diagnosis, prevention and cure of G6PD deficiency. The results may be of significance in anthropology and geneties as well.

Glucosephosphate Dehydrogenase↗

Glucose-6-phosphate dehydrogenase (G6PD) variants in Malaysian Chinese.

We screened 38 G6PD-deficient male Chinese neonates for known G6PD mutations using established PCR-based techniques. We found 50.0% (19 of 38) were mutation 1376G>T, 34.2% (13 of 38) were mutation 1388G>A, 5.2% (2 of 38 ) were mutation 95A>G and 2.2% (1 of 38) was mutation 1024C>T. In 7% (3 of 38) of the cases the mutations remained uncharacterised. Sixty three percent (24 of 38) of the G6PD deficient neonates had neonatal jaundice with 28.9 % (11 of 38) developing moderate to severe hyperbilirubinemia. The group of neonates with 1388 mutation showed the highest incidence of moderate to severe hyperbilirubinemia requiring phototherapy and/or exchange transfusion respectively. Majority (70%) of the G6PD deficient neonates showed severe enzyme deficiency. However, there was no meaningful association between the level of enzyme activity and the severity of neonatal jaundice. In summary, four mutations account for more than 90% of the G6PD deficiency cases among the Chinese in Malaysia and the pattern of distribution of the molecular variants is similar to those found among the Chinese in Taiwan and southern mainland China. Our findings also suggest the possible association of nt 1388 mutation with severe neonatal jaundice.

Amino Acid Substitution↗

Molecular characterisation of the glucose-6-phosphate dehydrogenase (G6PD) Ferrara II variant.

During the last ten years, molecular biological techniques such as cloning and sequencing and, more recently, polymerase chain reaction (PCR) amplification have led to the identification of the molecular defects responsible for more than fifty glucose-6-phosphate dehydrogenase (G6PD) variants. In this paper, we report the identification of the molecular abnormality underlying the G6PD Ferrara II variant, present in the Po delta area of Northern Italy. Biochemical characterisation shows an enzymatic activity of about 15% of normal (WHO class III), slow electrophoretic mobility, low Km for G6P, high percentage substrate analogue utilisation and a biphasic pH optimum curve. After PCR amplification, non-radioisotopic single-strand conformation polymorphism analysis carried out for the entire coding region has revealed a mobility shift in exon 8. Nucleotide sequencing has demonstrated a missense 844 G > C mutation, causing an Asp > His amino-acid replacement, known as being responsible for G6PD Seattle, G6PD Modena and G6PD Lodi.

Adult↗

Distribution of G6PD phenotypes in red blood cells of Southern African Negroids: evidence for somatic selection.

In a recent population study, we observed a striking deficit of G6PD heterozygotes among Southern African Negroid females. This finding was interpreted tentatively as evidence for a small number of hematopoetic stem cells in man. In a follow-up study we examined peripheral blood and cord blood in 547 mothers and in their newborn offspring. In mothers and sons, the frequencies of the G6PD alleles are apparently quite different. When the allele frequencies determined in sons are used for calculation of the expected phenotype frequencies in mothers and daughters, there is a large deficit of maternal G6PD AB phenotypes, and an equivalent surplus of G6PD homozygotes. However, no relevant heterozygote deficit is observed in newborn daughters. This discrepancy may be explained by the assumption that in peripheral blood of heterozygotes carrying the GdA- allele, G6PD-deficient cells progressively become eliminated during development from birth to adulthood. In other words, the large heterozygote deficit observed in adult females may be due to somatic selection rather than to a small pool of hematopoetic cells at the time of X differentiation.

Alleles↗

G6PD Huntsville: a new glucose-6-phosphate dehydrogenase associated with chronic hemolytic anemia.

We describe a previously unreported glucose-6-phosphate dehydrogenase (G6PD) variant. G6PD Huntsville was found in a Caucasian male, resident of Huntsville, Alabama who was investigated for otherwise unexplained chronic hemolytic anemia. An unusual feature of this unique, apparently hemolytic, G6PD mutant is that its red cell enzymatic activity has not been decreased. The mutant enzyme is unstable. Additionally, the enzyme variant is characterized by normal electrophoretic mobility, biphasic and slightly alkaline pH optimum, and abnormal kinetics for the natural substrates G6PD and NADP as well as the artificial substrates deamino NADP. Its activity for another artificial substrate 2-deoxy G6PD is normal. The inhibition constant for NADPH is normal. The subject has had no evidence of episodic jaundice.

Aged↗

G6PD Lozere and Trinacria-like. Segregation of two non hemolytic variants in a French family.

Two new G6PD variants have been found in red blood cells of the members of a French family originating from Lozere. The father is hemizygous for an electrophoretically fast variant with mild enzyme deficiency (50--60% of normal). The abnormal paternal G6PD gene is segregating in his daughter who is double heterozygous for maternal and paternal variants. This mutant enzyme, different from previously described variants is designated as Gd Lozere. The mother is heterozygous for another G6PD variant. Two sons are hemizygous for this latter mutant enzyme characterized by a moderate deficiency (25--30% of normal) and slower electrophoretic mobility with some slightly altered kinetic properties. This G6PD had been identified as Gd Trinacria like. These two abnormal enzymes are not associated with any hemolytic problem. Case reported is the first showing the segregation of two new mutant enzymes, distinct from common G6PD variants, among the members of the same family.

Electrophoresis, Starch Gel↗

A new glucose-6-phosphate dehydrogenase variant (G6PD Nagano) associated with congenital hemolytic anemia.

A new glucose-6-phosphate dehydrogenase (G6PD) variant associated with chronic nonspherocytic hemolytic anemia was reported. The patient, a 6-year-old Japanese male, was noticed to have hemolytic anemia soon after birth, and a diagnosis of G6PD deficiency was made at the age of 2. He had episodes of hemolytic crisis several times after upper respiratory infection. G6PD activity of the patient was 5.5% of normal. The enzymatic characteristics were examined when he was 5 years old, and his G6PD showed faster-than-normal electrophoretic mobility, low Km G6P, high Km NADP, low Ki NADPH, normal utilization of substrate analogues, heat instability, and a normal pH optimum curve. From these results, this was considered to be a new variant and was designated G6PD Nagano. Infection-induced hemolysis and chronic hemolytic anemia seem to be due to markedly impaired enzyme activity and thermal instability.

Anemia, Hemolytic, Congenital↗

Exogenous prostacyclin, but not prostaglandin E2, produces similar responses in both G6PD activity and RNA production as mechanical loading, and increases IGF-II release, in adult cancellous bone in culture.

Cyclic mechanical loading in vivo that leads to new bone formation is also associated in osteocytes and surface bone cells with almost immediate increases in G6PD activity, and later increases in RNA production. Both these early, loading-related, responses can be reproduced in organ culture of adult cancellous bone, and both are abolished by the presence of indomethacin in the culture medium at the time of loading. The implication that prostaglandins (PGs) are involved in the control of loading-related osteogenesis is supported by increases in prostacyclin (PGI2) and PGE2 release from cores of cancellous bone during loading. In the experiments reported here, PGE2 and PGI2 were added exogenously (10(-6) M) to perfusable cores of adult canine cancellous bone to determine whether they would simulate the loading-related responses in G6PD activity and RNA synthesis. PGE2 increased G6PD activity in surface cells and osteocytes within 8 minutes but had no effect on [3H]-uridine incorporation at 6 hours. PGI2 stimulated both G6PD activity and [3H]-uridine incorporation equally in osteocytes and surface cells. Neither PG produced any significant change in medium concentrations of IGF-I, and PGE2 had no effect on IGF-II. In contrast PGI2 elevated the medium concentration of IGF-II threefold. IGF-I and IGF-II were localized immunocytochemically to osteocytes and surface cells in both treated and untreated cores. Prostacyclin, but not PGE2, appears to imitate the early loading-related increases in G6PD activity and RNA synthesis in bone cells in situ. Prostacyclin, but not PGE2, also stimulates the early release of IGF-II.

Animals↗

Molecular identification of mutations in G6PD gene in patients with favism in Iran.

Glucose 6-phosphate dehydrogenase is a highly polymorphic enzyme encoded by a human X-linked gene (Xq2.8). This enzyme catalyses the first step of pentose phosphate pathway, that converts glucose 6-phosphate to 6-phosphogluconate with production of NADPH2. G6PD deficiency is the most common human metabolic inborn error affecting more than 400 million people world wide. The main clinical manifestations are acute hemolytic anemia and jaundice, triggered by infection or ingestion of Fava beans or oxidative drugs. A predominant variant of G6PD named Mediterranean is often associated with favism. This has been evident in several countries including Northern coastal provinces of Iran. Other current variants are Chatham and Cosenza. Molecular identification of the most prevalent mutations in G6PD gene was carried out in 71 males and females with G6PD deficiency. They were from Iranian Northern province of Golestan. DNA was extracted from blood samples and analyzed for known G6PD mutation by PCR and restriction fragment length polymorphisms (RFLP) technique. Adapting this method, revealed that Mediterranean mutation at nt 563(C-->T) is predominant in the area (69%) and 26.7% of patients have Chatham mutation at nt 1003(G-->A). Findings indicate a higher prevalence of these mutations, in Golestan compared to Mazandaran (66.2% Mediterranean and 19% Chatham mutation) and Gilan (86.4% Mediterranean and 9.71% Chatham mutations). Cosenza mutation at nt 1376(G-->C), by PCR-RFLP technique was not found among other 3 samples (4.3%). The similarity of these results with mutations in Italy indicates probable existence of a common ancestral origin in the observed populations.

Favism↗

Rapid detection of six common Chinese G6PD mutations by MALDI-TOF MS.

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is a common X-linked hereditary enzymopathy. We describe here the techniques based on matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) and multiprimer extension (multi-PEX) to detect the most common Chinese G6PD mutations, which are the single-point mutations G-->T at nt 1376, G-->A at nt 1388, A-->G at nt 95, G-->T at nt 392, C-->T at nt 1024, and C-->T at nt 1311. Fifteen samples were genotyped using this method coupled with direct sequencing, after identification of G6PD mutations by ARMS. In this study, we identified a mutation G-->T at nt 1376, which had been G-->A at nt 1388 using ARMS, while the result of sequencing corresponds with ours. This indicates the reliability of this method. Furthermore, since it can scan six common Chinese G6PD mutations simultaneously in one mass spectrum, this approach could be used to fast diagnose these G6PD mutations accurately in large-scale analysis.

China↗

Cellular glucose-6-phosphate dehydrogenase (G6PD) status modulates the effects of nitric oxide (NO) on human foreskin fibroblasts.

Glucose-6-phosphate dehydrogenase (G6PD) plays an important role in cellular redox homeostasis, which is crucial for cell survival. In the present study, we found that G6PD status determines the response of cells exposed to nitric oxide (NO) donor. Treatment with NO donor, sodium nitroprusside (SNP), caused apoptosis in G6PD-deficient human foreskin fibroblasts (HFF1), whereas it was growth stimulatory in the normal counterpart (HFF3). Such effects were abolished by NO scavengers like hemoglobin. Ectopic expression of G6PD in HFF1 cells switched the cellular response to NO from apoptosis to growth stimulation. Experiments with 1H-¿1,2,4ŏxadiazolo¿4, 3-aquinoxalin-1-one and 8-bromo-cGMP showed that the effects of NO on HFF1 and HFF3 cells were independent of cGMP signalling pathway. Intriguingly, trolox prevented the SNP-induced apoptosis in HFF1 cells. These data demonstrate that G6PD plays a critical role in regulation of cell growth and survival.

Apoptosis↗

Histochemical studies on the relationship between the morphology of the Golgi apparatus and G6PD activity in the locus coeruleus and dorsal vagal nucleus of the rat (application of karyometry).

Histochemical studies on the distribution of TPPase and G6PD in the neurons of locus coeruleus (LC) and dorsal vagal nucleus (DVN) of rats have been conducted by using the TPPase method, the G6PD method, karyometry, and statistics under normal conditions. 1. Neurons of the LC and DVN may undergo phasic changes of the GOLGI apparatus (GA) under normal condition. 2. No significant difference was found between neurons of the LC and DVN in regard to the GA morphology, but in general the latter revealed more complicated and developed GA than in the former. 3. Surprisingly, the G6PD activity of LC neurons was very weak. This is in agreement with the previous report by IIJIMA and IMAI (1975), and in disagreement with FRIEDE (1966). 4. An intimate parallel relationship was found between the GA morphology and G6PD activity in the DVN. The findings support the vigorous synthesizing activity found in the previous study of the rat supraoptic nucleus (IIJIMA 1979). In contrast to the DVN, such a parallel relationship between the Ga shape and G6PD activity was absent in the LC. Both findings strongly suggest that the role of the GA may be functionally different in the LC and DVN.

Animals↗

Natural selection of hemi- and heterozygotes for G6PD deficiency in Africa by resistance to severe malaria.

Glucose-6-phosphate dehydrogenase (G6PD) deficiency, the most common enzymopathy of humans, affects over 400 million people. The geographical correlation of its distribution with the historical endemicity of malaria suggests that this disorder has risen in frequency through natural selection by malaria. However, attempts to confirm that G6PD deficiency is protective in case-control studies of malaria have yielded conflicting results. Hence, for this X-linked disorder, it is unclear whether both male hemizygotes and female heterozygotes are protected or, as frequently suggested, only females. Furthermore, how much protection may be afforded is unknown. Here we report that, in two large case-control studies of over 2,000 African children, the common African form of G6PD deficiency (G6PD A-) is associated with a 46-58% reduction in risk of severe malaria for both female heterozygotes and male hemizygotes. A mathematical model incorporating the measured selective advantage against malaria suggests that a counterbalancing selective disadvantage, associated with this enzyme deficiency, has retarded its rise in frequency in malaria-endemic regions. Although G6PD deficiency is now regarded as a generally benign disorder, in earlier environmental conditions it could have been significantly disadvantageous.

Africa↗

Neonatal nucleated red blood cells in G6PD deficiency.

The objective of this study is to study the absolute number of nucleated red blood cells (RBC) at birth, an index of active fetal erythropoiesis, in infants with G6PD deficiency and in controls. We tested the hypothesis that hematocrit and hemoglobin would be lower, and absolute nucleated RBC counts higher, in the G6PD deficient and that these changes would be more prominent in infants exposed passively to fava bean through maternal diet. Thirty-two term infants with G6PD deficiency were compared with 30 term controls. Complete blood counts with manual differential counts were obtained within 12 hours of life. Absolute nucleated RBC and corrected leukocyte counts were computed from the Coulter results and the differential count. G6PD deficient patients did not differ from controls in terms of gestational age, birth weight, or Apgar scores or in any of the hematologic parameters studied, whether or not the mother reported fava beans consumption in the days prior to delivery. Although intrauterine hemolysis is possible in G6PD deficient fetuses exposed passively to fava beans, our study supports that such events must be very rare.

Adult↗