A computational study of structural differences of binding of NADP+ and G6P substrates to G6PD Mediterraneanc.563T, G6PD A-c.202A/c.376G, G6PD Cairoc.404C and G6PD Gazac.536A mutations.

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is a common X-linked inherited enzymopathic disorder that may lead to transfusion-requiring acute hemolytic anemia (AHA) triggered by fava beans ingestion, infection or some drugs. The gene encoding for G6PD carries a large number of genetic variants that have varying pathogenicity. We reported on three G6PD variants in the Gaza Strip Palestinian population with differing clinical impacts and frequencies: G6PD Mediterraneanc.563T, African G6PD A-c.202A/c.376G, and G6PD Cairoc.404C. We also identified a novel G6PD missense (Ser179Asn) mutation c.536G > A "G6PD Gaza". In this work we explore the effect of these four genetic variants on the structural and substrate (NADP+ and G6P) binding characteristics of the G6PD enzyme using the Monte Carlo (MC) flexible docking and molecular dynamics (MD) simulation approaches. We report that G6PD A-c.202A/c.376G, G6PD Mediterraneanc.563T, G6PD Cairoc.404C and G6PD Gazac.536A mutations cause significant structural changes in G6PD enzyme to induce conformational instability leading to the loss of binding of one or both substrates and are causative of G6PD deficiency.

Study of Glucose-6-Phosphate Dehydrogenase (G6PD) Deficiency and Genotype Polymorphism of G6PD B and G6PD (A+/A-) in Patients Treated for Plasmodium vivax Malaria in a Tertiary Care Hospital in North East India.

Introduction Glucose-6-phosphate dehydrogenase (G6PD) enzyme deficiency is the most common enzymopathy in humans, and its distribution has been historically described to be closely associated with that of malaria. North East India provides optimal conditions for transmission of malaria and bears a considerable burden of Plasmodium vivax (P. vivax) malaria. Primaquine, a mainstay in the treatment of vivax malaria, may trigger episodes of acute hemolysis in patients with G6PD deficiency. The present study sought to delineate the frequency and genotypes of G6PD deficiency among patients suffering from vivax malaria infections.  Methods Blood specimens from 80 individuals diagnosed with vivax malaria underwent enzyme assay for G6PD deficiency. Samples with deficient phenotype underwent isolation of DNA using a genomic DNA isolation kit (Qiagen India Pvt. Ltd., New Delhi, India). The genomic DNA underwent amplification, serial denaturation, annealing, extension, final extension followed by digestion with restriction endonucleases Nla III and Fok I. The digested products were subjected to horizontal agarose electrophoresis for the separation of digested fragments. Samples without nucleotide 376 adenine→guanine (A→G) mutation were classified as G6PD B. Those with the mutation were further classified into G6PD A(+) and G6PD A(-) based on the presence of Nla III site. Results Twenty-seven out of 80 individuals (33.75%) with P. vivax malaria were found to have G6PD deficiency, of which a majority (n=24) had G6PD B genotype. Three individuals had Asparagine→Aspartic Acid mutation at position 376 (A→G), of which G6PD A(+) and G6PD A(-) were present in two and one cases, respectively. Conclusion G6PD deficiency was noted in about a third of patients with vivax malaria. Since primaquine therapy is contraindicated in this group of patients, there is a rationale for looking into screening patients with vivax malaria from the region prior to primaquine therapy. Further large scale studies may substantiate this and help in better genotypic and geographic characterization of G6PD deficiency in the region.

G6PD A- is the major cause of G6PD deficiency among the Siddis of Karnataka, India.

Background: Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most common human erythroenzymopathy affecting more than 400 million people worldwide. G6PD deficiency was reported in India more than 50 years ago and the prevalence rate varies from 5.7% to 27.9% in different caste and tribal groups.Aim: To study the prevalence of, and the mutations causing, G6PD deficiency among the Siddis of Karnataka.Subjects and methods: A total of 755 individuals were screened using the DPIP dye decolorisation method and the deficiency was further confirmed by quantitative assay. Molecular characterisation was performed by PCR-RFLP method and DNA sequencing. Biochemical characterisation was performed as per WHO criteria.Results: Of the 755 individuals, 71 individuals (9.4%) were found to be G6PD deficient with an enzyme activity ranging from 0.02 to 3.83 IU/gm Hb. Mutational analysis could be performed on 49 G6PD deficient individuals and 45 (91.8%) of them showed the presence of the G6PD A- variant while the remaining 4 (8.2%) had the G6PD Kerala-Kalyan mutation. Microsatellite analysis in G6PD A- individuals showed the presence of 166/195 bp, AC/CTT alleles.Conclusions: G6PD deficiencies among the Siddis are predominantly due to G6PD A- mutation. Furthermore, biochemical parameters and the microsatellite repeat markers in the Siddi A- chromosome confirmed they are African descendants with Indian admixture.

Evidence of positively selected G6PD A- allele reduces risk of Plasmodium falciparum infection in African population on Bioko Island.

BACKGROUND: Glucose-6-phosphate dehydrogenase (G6PD) is an essential enzyme that protects red blood cells from oxidative damage. Although G6PD-deficient alleles appear to confer a protective effect of malaria, the link with clinical protection against Plasmodium infection is conflicting. METHODS: A case-control study was conducted on Bioko Island, Equatorial Guinea and further genotyping analysis used to detect natural selection of the G6PD A- allele. RESULTS: Our results showed G6PD A- allele could significantly reduce the risk of Plasmodium falciparum infection in male individuals (adjusted odds ratio [AOR], 0.43; 95% confidence interval [CI], 0.20-0.93; p < .05) and homozygous female individuals (AOR, 0.11; 95% CI, 0.01-0.84; p < .05). Additionally, the parasite densities were significantly different in the individuals with different G6PD A- alleles and individual levels of G6PD enzyme activity. The pattern of linkage disequilibrium and results of the long-range haplotype test revealed a strong selective signature in the region encompassing the G6PD A- allele over the past 6,250 years. The network of inferred haplotypes suggested a single origin of the G6PD A- allele in Africans. CONCLUSION: Our findings demonstrate that glucose-6-phosphate dehydrogenase (G6PD) A- allele could reduce the risk of P. falciparum infection in the African population and indicate that malaria has a recent positive selection on G6PD A- allele.