Genetic Analysis of Two Novel GPI Variants Disrupting H Bonds and Localization Characteristics of 55 Gene Variants Associated with Glucose-6-phosphate Isomerase Deficiency

Objective:Glucose-6-phosphate isomerase(GPI)deficiency is a rare hereditary nonspherocytic hemolytic anemia caused by GPI gene variants.This disorder exhibits wide heterogeneity in its clinical manifestations and molecular characteristics,often posing challenges for precise diagnoses using conventional methods.To this end,this study aimed to identify the novel variants responsible for GPI deficiency in a Chinese family.Methods:The clinical manifestations of the patient were summarized and analyzed for GPI deficiency phenotype diagnosis.Novel compound heterozygous variants of the GPI gene,c.174C>A(p.Asn58Lys)and c.1538G>T(p.Trp513Leu),were identified using whole-exome and Sanger sequencing.The AlphaFold program and Chimera software were used to analyze the effects of compound heterozygous variants on GPI structure.Results:By characterizing 53 GPI missense/nonsense variants from previous literature and two novel missense variants identified in this study,we found that most variants were located in exons 3,4,12,and 18,with a few localized in exons 8,9,and 14.This study identified novel compound heterozygous variants associated with GPI deficiency.These pathogenic variants disrupt hydrogen bonds formed by highly conserved GPI amino acids.Conclusion:Early family-based sequencing analyses,especially for patients with congenital anemia,can help increase diagnostic accuracy for GPI deficiency,improve child healthcare,and enable genetic counseling.

The diagnostic significance of glucose-6-phosphate isomerase (G6PI) antigen and anti-G6PI antibody in rheumatoid arthritis patients

Objective: To investigate whether glucose-6-phosphate isomerase (G6PI) antigen and anti-G6PI antibodies could be applied for the clinical diagnostic markers of rheumatoid arthritis (RA) and its associations with RA activity states. Methods: The levels of G6PI antigens and anti-G6PI Abs in sera from 176 RA patients in different states, 35 non-RA patients and 100 healthy donors and in synovia fluids from 33 patients and 11 non-RA patients were measured by ELISA. Results: The sensitivity and specificity of G6PI antigens in the RA patients were 75.0% and 93.3%, respectively. The levels of serum G6PI antigens in 176 RA patients were significantly higher than non-RA patients and the health controls. Especially, there was a significant difference between the active phase and the inactive phase in G6PI antigens levels. The levels of G6PI antigens in synovia fluid were also significantly higher in RA groups than in non-RA patients. With the values of the anti-G6PI Abs in sera, there were no marked differences among RA, non-RA patients and health controls. Also, there was no significant difference between the active phase and the inactive phase in RA patients. However, there were no significant differences of G6PI and anti-G6PI between RA patients and health controls in synovial fluid. Conclusions: G6PI is highly correlated with the activity states of RA, and could be applied for a clinical biomarker with high sensitivity and specificity for the diagnosis of RA.

Is glucose-6-phosphate dehydrogenase deficiency more prevalent in Carrion's disease endemic areas in Latin America?

Glucose-6-phosphate dehydrogenase(G6PD) is a cytoplasmic enzyme with an important function in cell oxidative damage prevention.Erythrocytes have a predisposition towards oxidized environments due to their lack of mitochondria,giving G6 PD a major role in its stability.G6 PD deficiency(G6PDd) is the most common enzyme deficiency in humans:it affects approximately 400 million individuals worldwide.The overall G6 PDd allele frequency across malaria endemic countries is estimated to be 8%.corresponding to approximately 220 million males and 133 million females.However,there are no reports on the prevalence of G6 PDd in Andean communities where bartonellosis is prevalent.

Prevalence of Glucose-6-Phosphate Dehydrogenase (G6PD) Deficiency in India: A Systematic Review

Glucose-6-Phosphate Dehydrogenase (G6PD) deficiency is the most common enzyme deficiency of human erythrocyte affecting more than 400 million people worldwide. In India, G6PD deficiency was first reported in 1963 and since then various investigations have been conducted across country. The objective of this work was to study the prevalence of G6PD deficiency in different ethnic, caste and linguistic groups of Indian population. A systematic search of published literature was undertaken and the wide variability of G6PD deficiency has been observed ranging from 0% - 30.7% among the different caste, ethnic, and linguistic groups of India. It was observed that the incidence of G6PD deficiency was found to be considerably higher among the tribes (9.86%) as compared to other ethnic groups (7.34%) and significantly higher in males as compared to females.

Glucose-6-phosphate isomerase is associated with disease activity and declines in response to infliximab treatment in rheumatoid arthritis

Background:Rheumatoid arthritis (RA), a systemic autoimmune disease characterized by synovial inflammation, can cause cartilage and bone damage as well as disability. The aim of this study was to explore whether serum glucose-6-phosphate isomerase (GPI) is correlated with disease activity and the value of GPI in the evaluation of infliximab treatment in patients with RA.Methods:Sixty-two patients with RA who had an inadequate response to methotrexate (MTX) were enrolled in Peking University People’s Hospital from July 1, 2016 to July 31, 2018. Infliximab (3 mg/kg, intravenous at weeks 0, 2, and 6 and then every 8 weeks) was administered to patients with stable background MTX therapy. Serum samples were obtained at baseline and week 18. Serum GPI levels were determined using enzyme-linked immunosorbent assay. The associations between serum GPI levels and clinical features were analyzed.Results:Serum GPI was positively correlated with Disease Activity Score in 28 joints (DAS28), swollen joint count, tender joint count and C-reactive protein level ( P < 0.001, P < 0.001, P < 0.001, and P = 0.033, respectively). The change of DAS28 in GPI-positive patients was greater than that in GPI-negative patients ( P < 0.001). Compared with those for patients receiving MTX monotherapy at baseline, the GPI levels were significantly declined when MTX was combined with infliximab ( P < 0.001). Conclusion:Serum GPI is related to disease activity and clinical response to infliximab treatment.

Characterization of glucose-6-phosphate dehydrogenase deficiency and identification of a novel haplotype 487G>A/IVS5-612(G>C) in the Achang population of southwestern China

The prevalence of glucose-6-phosphate dehydrogenase (G6PD) deficiency and its gene mutations were studied in the Achang population from Lianghe County in Southwestern China. We found that 7.31% (19 of 260) males and 4.35% (10 of 230) females had G6PD deficiency. The molecular analysis of G6PD gene exons 2―13 was performed by a PCR-DHPLC-Sequencing or PCR-Sequencing. Sixteen inde-pendent subjects with G6PD Mahidol (487G>A) and the new polymorphism IVS5-612 (G>C), which combined into a novel haplotype, were identified accounting for 84.2% (16/19). And 100% Achang G6PD Mahidol were linked to the IVS5-612 C. The percentage of G6PD Mahidol in the Achang group is close to that in the Myanmar population (91.3% 73/80), which implies that there are some gene flows between Achang and Myanmar populations. Interestingly, G6PD Canton (1376G>T) and G6PD Kaiping (1388G>A), which were the most common G6PD variants from other ethnic groups in China, were not found in this Achang group, suggesting that there are different G6PD mutation profiles in the Achang group and other ethnic groups in China. Our findings appear to be the first documented report on the G6PD genetics of the AChang people, which will provide important clues to the Achang ethnic group origin and will help prevention and treatment of malaria in this area.

Identification of Contaminations Hiding Beneath the α- and β-Subunits of Partially Purified Nitrogenase MoFe Protein on the Sodium Dodecyl Sulfate Gel

To identify the unknown proteins that would contaminate the α- and β-subunits of nitrogenase MoFe protein on sodium dodecyl sulfate-polyacrylamide gel electrophoresis （SDS-PAGE）, the partially purified MoFe protein （Avl） preparation was obtained from Azotobacter vinelandii Lipmann OP by chroma- tography on DEAE-cellulose （DE52） and Sephacryl S-200 columns and analyzed by PAGE and matrix- assisted laser desorption/ionization time-of-flight （MALDI-TOF） mass spectrometry. The Av 1 preparation was shown to have two main bands at the position of the α- and β-subunits of crystalline Avl on the SDS gel. However, on the anoxic native PAGE, in addition to the Avl band, the preparation was shown to have three other main bands that migrated slower than Av 1. Of these three main bands, the protein with the fastest migration was identified as bacterioferritin elsewhere. The proteins on the other two bands, termed Upper and Middle, were suggested to be two different homopolymers with the same apparent subunit electrophoretic mobilities as the α- and β-subunits of Avl, respectively. By analysis of MALDI-TOF mass spectrometry, the Upper was identified as GroEL, which belongs to the heat shock protein 60 family, and the Middle was identified as glucose-6-phosphate isomerase （PGI）. In our preparation, anoxic native electrophoresis indicated that GroEL was composed of 14 identical subunits and that PGI was composed of 10 identical subunits. This is the first report of PGI, with so many subunits. The contaminating proteins in the Av 1 preparation, mainly GroEL and PGI, could be totally or partially removed from Av 1 if the shoulders and center of the elution peak were collected separately from the Sephacryl S-200 column and the center fraction was purified further by Q-Sepharose developed with an NaC1 concentration gradient. Thus, Avl with more than 90% purity was obtained. Obviously, this modified method is useful for the purification of mutant MoFe proteins with a high purity.