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PubMedDate not supplied

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.

Amino Acid Substitution↗
PubMed2003

Semiquantitative screening test for G6PD deficiency detects severe deficiency but misses a substantial proportion of partially-deficient females.

Neonatal screening for G6PD deficiency has long been established in many countries. The aim of the study was to determine whether the routine semiquantitative fluorescent spot test could detect all cases of G6PD deficiency, including those cases with partial deficiency (residual red cell G6PD activity between 20-60% of normal). We compared the results of G6PD screening by the semiquantitative fluorescent spot test and quantitative G6PD activity assay on a group of 976 neonates and 67 known female heterozygotes. The values for mean G6PD activity of G6PD-normal neonates and 293 healthy adult females were determined. There was no significant difference in the mean normal G6PD activity between the two racial groups in the neonates (669 Malays, 307 Chinese) and in the 293 healthy adult females (150 Malays, 143 Chinese) group. The values for the upper limits of total deficiency (20% of normal residual activity) for neonates and adult females were 2.92 U/gHb and 1.54 U/gHb, respectively. The upper limits of partial deficiency (60% of normal residual activity) were 8.7 U/gHb and 4.6 U/gHb respectively. The prevalence of G6PD deficiency among the male neonates was 5.1% (26) by both the fluorescent spot test and the enzyme assay method. The G6PD activity levels of all 26 cases of G6PD-deficient male neonates were < 20% normal (severe enzyme deficiency). In the female neonate group, the frequency of G6PD deficiency was 1.3% (6 of 472) by the fluorescent spot test and 9.35% (44 of 472) by enzyme assay. The 6 cases diagnosed as deficient by the fluorescent spot test showed severe enzyme deficiency (< 2.92 U/gHb). The remaining 38 female neonates had partial enzyme deficiency and all were misdiagnosed as normal by the fluorescent spot test. In the female heterozygote group, G6PD deficiency was diagnosed in 53% (35 of 67) by enzyme assay and in 7.5% (4 of 67) of cases by the fluorescent spot test. The 4 cases detected by fluorescent spot test had severe enzyme deficiency (<1.6 U/gHb). The remaining 31 (46.3%) cases, diagnosed as normal by fluorescent spot test, showed partial G6PD deficiency. In conclusion, we found that the semiquantitative fluorescent spot test could only diagnose cases of total G6PD deficiency and misclassified the partially-deficient cases as normal. In this study, the overall prevalence of G6PD deficiency was 3.28% by the semiquantitative fluorescent spot test and 7.17% by enzyme assay. This means that 3.9% of G6PD-deficient neonates were missed by the routine fluorescent spot test and they were found to be exclusively females. This study demonstrates a need to use a method that can correctly classify female heterozygotes with partial G6PD deficiency. The clinical implication is that these individuals may be at risk of the hemolytic complication of G6PD deficiency.

Adult↗
PubMed1999

Several mutations including two novel mutations of the glucose-6-phosphate dehydrogenase gene in Polish G6PD deficient subjects with chronic nonspherocytic hemolytic anemia, acute hemolytic anemia, and favism.

DNA sequencing revealed seven different glucose-6-phosphate dehydrogenase (G6PD) mutations in G6PD deficient subjects from 10 Polish families. Among them we found two novel mutations: 679C-->T (G6PD Radlowo, class 2) and a 1006A-->G (G6PD Torun, class 1). Variant G6PD Radlowo was characterized biochemically. Both novel mutations were analyzed using a model of the tertiary structure of the human enzyme. The main chain of G6PD Torun is different from the wild-type G6PD. The remaining mutations identified by us in deficient Polish patients were: 542A-->T (G6PD Malaga), 1160G-->A (G6PD Beverly Hills), 1178G-->A (G6PD Nashville), 1192G-->A (G6PD Puerto Limon), and 1246G-->A (G6PD Tokyo). Variant Tokyo was found in four families. In one of them favism was the first clinical sign of G6PD deficiency and chronic nonspherocytic hemolytic anemia (CNSHA) was diagnosed later. Variants G6PD Nashville and G6PD Puerto Limon were accompanied by the silent mutation 1311C-->T of the G6PD gene.

Acute Disease↗
PubMed2003

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

We performed DNA analysis using cord blood samples on 86 male Malay neonates diagnosed as G6PD deficiency in the National University of Malaysia Hospital by a combination of rapid PCR-based techniques, single-stranded conformation polymorphism analysis (SSCP) and DNA sequencing. We found 37.2% were 871G>A (G6PD Viangchan), 26.7% were nt 563 C>T (G6PD Mediterranean) and 15.1% were 487G>A (G6PD Mahidol) followed by 4.7% 1376G>T (G6PD Canton), 3.5% 383T>C (G6PD Vanua Lava), 3.5% 592C>T (G6PD Coimbra), 2.3% 1388G>A (G6PD Kaiping), 2.3% 1360C>T (G6PD Union), 2.3% 1003G>A (G6PD Chatham), 1.2% 131C>G (G6PD Orissa) and 1.2% 1361G>A (G6PD Andalus). Seventy-one (82.6%) of the 86 G6PD-deficient neonates had neonatal jaundice. Fifty seven (80%) of the 71 neonates with jaundice required phototherapy with only one neonate progressing to severe hyperbilirubinemia (serum bilirubin >340 micromol/l) requiring exchange transfusion. There was no significant difference in the incidence of neonatal jaundice, mean serum bilirubin level, mean age for peak serum bilirubin, percentage of babies requiring phototherapy and mean number of days of phototherapy between the three common variants. In conclusion, the molecular defects of Malay G6PD deficiency is heterogeneous and G6PD Viangchan, Mahidol and Mediterranean account for at least 80% of the cases. Our findings support the observation that G6PD Viangchan and Mahidol are common Southeast Asian variants. Their presence in the Malays suggests a common ancestral origin with the Cambodians, Laotians and Thais. Our findings together with other preliminary data on the presence of the Mediterranean variant in this region provide evidence of strong Arab influence in the Malay Archipelago.

DNA Mutational Analysis↗
PubMedDate not supplied

Molecular heterogeneity of glucose-6-phosphate dehydrogenase (G6PD) variants in Italy.

BACKGROUND: Glucose-6-phosphate dehydrogenase deficiency, one of the most common human enzymatic defects, is characterized by extreme molecular and biochemical heterogeneity. The molecular bases of almost all polymorphic italian variants have now been identified and the overall heterogeneity is lower than expected from biochemical data. METHODS: We examined 161 G6PD-deficient subjects (130 males and 31 females) originating from different parts of Italy. G6PD activity and molecular characterization were determined in all the subjects analyzed. RESULTS: We found the G6PD Mediterranean genotype in roughly 70%, G6PD Union and G6PD Seattle in about 6% and G6PD A- in 4% of the samples analyzed. G6PD S. Antioco and G6PD Cosenza were less frequent (1.2%), and single cases of G6PD Partenope and G6PD Tokyo were also detected. CONCLUSIONS: We report the frequency and distribution of the most common G6PD variants in Italy. Greater molecular heterogeneity than described by others was observed, especially in Sardinia. Among the severe deficient variants, G6PD Mediterranean has a higher prevalence in Sardinia (83%) than in continental Italy (61%), as does G6PD Union (10% and 4%, respectively). G6PD Seattle and A-, associated with mild G6PD deficiency, are by contrast more frequent in continental Italy.

Alleles↗
PubMed2000

Human glucose-6-phosphate dehydrogenase (G6PD) gene transforms NIH 3T3 cells and induces tumors in nude mice.

The main physiological function of glucose-6-phosphate dehydrogenase (G6PD) is to produce NADPH and ribose 5-phosphate, which are essential for reductive biosynthesis and nucleic acid synthesis. In normal cells, G6PD expression is tightly controlled; however, in many tumors, regulation of its expression is altered, resulting in a significant increase in G6PD activity. To investigate the potential role of G6PD in tumorigenesis, we transfected NIH 3T3 cells with human G6PD cDNA. Cells overexpressing G6PD showed altered cell morphology and exhibited tumorigenic properties. In contrast to the control cells or cells transfected with mutated G6PD cDNA, G6PD-overexpressing cells were not contact inhibited and exhibited anchorage-independent growth. They divided more quickly and induced rapidly growing, large fibrosarcomas in nude mice. Moreover, the induced tumorigenic properties were positively correlated with the level of G6PD activity. Interestingly, treatment with buthionine SR-sulfoximine (BSO), a glutathione depletion agent, decreased the colony-forming efficiency of G6PD-overexpressing cells in soft agar, which implicates that alteration of the redox balance may be involved in G6PD-induced tumorigenesis. A comparative analysis of the expression level of G6PD in a variety of human cancer cell lines was also performed. Northern- and Western-blot analyses revealed that G6PD was particularly overexpressed in human esophageal cancer cell lines. Our observations indicate that G6PD may act as a potential oncogene, whose overexpression plays a critical role in neoplastic transformation.

3T3 Cells↗
PubMedDate not supplied

Molecular basis of G6PD deficiency in India.

G6PD deficiency has been reported from India more than 30 years ago and about 13 variants have been characterized biochemically. Here, we report the results of an epidemiological study investigating G6PD deficiency and the mutations among 14 heterogenous populations of India. Of the 3166 males tested, 332 (10.5%) were found to be G6PD-deficient and the prevalence rate varied from 5.7% to 27.9% in the different population groups. Molecular characterization revealed that G6PD Mediterranean (563 C-->T) was the commonest (60.4%) deficient variant followed by G6PD Kerala-Kalyan (949 G-->A; 24.5%) and G6PD Orissa (131 C-->G; 13.3%). G6PD Mediterranean had a more widespread distribution as compared to G6PD Kerala-Kalyan and G6PD Orissa and was associated with both 1311 C and 1311 T polymorhism. G6PD Mediterranean was found to have significantly lower red cell enzyme activity and more severe clinical manifestations than the other two. G6PD Chatham (1003 G-->A) with undetected red cell enzyme activity and G6PD Insuli (989 G-->A) with normal G6PD activity were very rare in the Indian population. The absence of a large number of mutations causing G6PD deficiency points to the fact that the genetic diversity of these populations is considerably lowered than expected.

Ethnicity↗
PubMed1981

G6PD Napoli and Ferrara II: two new glucose-6-phosphate dehydrogenase variants having similar characteristics but different intracellular lability and specific activity.

Two new glucose-6-phosphate dehydrogenase (G6PD, D-glucose 6-phosphate: NADP oxido reductase, E.C. 1.1.1.49) variants, designated G6PD Napoli and G6PD Ferrara II, are described in propositi from two unrelated families. Characterization side by side of the two variants according to W.H.O. recommendations reveals minor differences which are mostly related to utilization of artificial substrates (increased in both cases as compared with normal G6PD type B). Other properties, which are not significantly distinctive between the two variants, are an enzyme activity amounting to nearly 20% of normal, a decreased electrophoretic mobility, decreased Km values for glucose-6-phosphate and NADP, normal thermostability and biphasic pH curves. However, marked differences emerged between the two variants and between either variant and G6PD B as well, when a number of microtechniques were used. These were: (1) the half-lives of G6PD Napoli and G6PD Ferrara II are 16 and 29 d, respectively, while that of G6PD B is 63 d; (2) the specific activities, measured by a method involving direct estimation of G6PD protein on sodium dodecyl sulphate polyacrylamide gel electrophoretic tracings, are 166 I.U./mg (G6PD Napoli) and 59 I.U./mg (G6PD Ferrara II), as compared with normal value of 180 I.U./mg (G6PD B). On the whole, these findings allow the conclusion that the deficiency of catalytic activity is related to an accelerated though distinctive decay of both mutant enzyme proteins within the affected erythrocytes and that a significant impairment of catalytic efficiency is also involved, as a result of the underlying structural mutation in the case of G6PD Ferrara II.

Adult↗
PubMed2026

KLF5-driven G6PD protects lung squamous cell carcinoma from ferroptosis by sustaining mitochondrial homeostasis and SLC7A11-dependent cystine uptake.

AIMS: Lung squamous cell carcinoma (LUSC) is a highly aggressive malignancy with limited therapeutic options. Ferroptosis has emerged as a promising antitumor strategy. However, the metabolic determinants governing ferroptotic vulnerability in LUSC remain incompletely understood. We investigated glucose-6-phosphate dehydrogenase (G6PD) in this context. MATERIALS AND METHODS: In vitro models using small interfering RNA (siRNA)-mediated G6PD depletion, together with pharmacological studies using 6-aminonicotinamide (6-AN) and LUSC xenograft models, were employed to investigate the underlying mechanisms. KEY FINDINGS: G6PD was markedly upregulated in LUSC, and analysis of the Cancer Genome Atlas lung squamous cell carcinoma (TCGA-LUSC) cohort showed that elevated G6PD expression was associated with advanced clinicopathological features and poorer overall survival. While ferroptosis inducers (erastin and RSL3) did not alter G6PD mRNA, they robustly increased G6PD protein during ferroptotic stress. Genetic or pharmacological inhibition of G6PD significantly sensitized LUSC cells to RSL3-induced ferroptosis, evidenced by enhanced lipid peroxidation, glutathione depletion, and ferrostatin-1-reversible cell death. Mechanistically, G6PD inhibition led to mitochondrial ferrous iron accumulation, elevated reactive oxygen species, impaired respiration, and activation of PINK1/Parkin-dependent mitophagy, which further exacerbated ferroptotic injury. In vivo, combined treatment with 6-aminonicotinamide and RSL3 markedly suppressed LUSC xenograft growth and enhanced biochemical markers of ferroptotic stress. Furthermore, G6PD protects cells by positively regulating the cystine/glutamate antiporter SLC7A11 to maintain redox homeostasis. Upstream, the oncogenic factor Kr&#xfc;ppel-like factor 5 (KLF5) directly activates G6PD transcription. SIGNIFICANCE: Our findings identify a KLF5-G6PD-SLC7A11 axis as a critical metabolic safeguard against ferroptosis in LUSC. Targeting G6PD disrupts mitochondrial homeostasis, enhances mitophagy-dependent oxidative stress, and sensitizes tumors to ferroptotic therapy, highlighting a promising therapeutic strategy for LUSC.

Ferroptosis↗
PubMed2005

The extent of linkage disequilibrium caused by selection on G6PD in humans.

The gene coding for glucose-6-phosphate dehydrogenase (G6PD) is subject to positive selection by malaria in some human populations. The G6PD A- allele, which is common in sub-Saharan Africa, is associated with deficient enzyme activity and protection from severe malaria. To delimit the impact of selection on patterns of linkage disequilibrium (LD) and nucleotide diversity, we resequenced 5.1 kb at G6PD and approximately 2-3 kb at each of eight loci in a 2.5-Mb region roughly centered on G6PD in a diverse sub-Saharan African panel of 51 unrelated men (including 20 G6PD A-, 11 G6PD A+, and 20 G6PD B chromosomes). The signature of selection is evident in the absence of genetic variation at G6PD and at three neighboring loci within 0.9 Mb from G6PD among all individuals bearing G6PD A- alleles. A genomic region of approximately 1.6 Mb around G6PD was characterized by long-range LD associated with the A- alleles. These patterns of nucleotide variability and LD suggest that G6PD A- is younger than previous age estimates and has increased in frequency in sub-Saharan Africa due to strong selection (0.1 < s < 0.2). These results also show that selection can lead to nonrandom associations among SNPs over great physical and genetic distances, even in African populations.

Alleles↗