Kinetics of glucose-6-phosphate dehydrogenase (G6PD) activity during Plasmodium vivax infection: implications for early radical malaria treatment.

BACKGROUND: Plasmodium vivax relapses due to dormant liver hypnozoites can be prevented with primaquine. However, the dose must be adjusted in individuals with glucose-6-phosphate-dehydrogenase (G6PD) deficiency. In French Guiana, assessment of G6PD activity is typically delayed until day (D)14 to avoid the risk if misclassification. This study assessed the kinetics of G6PD activity throughout P. vivax infection to inform the timing of treatment. METHODS: For this retrospective monocentric study, data on G6PD activity between D1 and D28 after treatment initiation with chloroquine or artemisinin-based combination therapy were collected for patients followed at Cayenne Hospital, French Guiana, between January 2018 and December 2020. Patients were divided into three groups based on the number of available G6PD activity assessments: (i) at least two measurements during the P. vivax malaria infection; (ii) two measurements: one during the current infection and one previously; (iii) only one measurement during the malaria infection. RESULTS: In total, 210 patients were included (80, 20 and 110 in groups 1, 2 and 3, respectively). Data from group 1 showed that G6PD activity remained stable in each patient over time (D1, D3, D7, D14, D21, D28). None of the patients with normal G6PD activity during the initial phase (D1-D3) of the malaria episode (n = 44) was categorized as G6PD-deficient at D14. Patients with G6PD activity < 80% at D1 or D3 showed normal activity at D14. Sex and reticulocyte count were statistically associated with G6PD activity variation. In the whole sample (n = 210), no patient had severe G6PD deficiency (< 10%) and only three between 10 and 30%, giving a G6PD deficiency prevalence of 1.4%. Among the 100 patients from group 1 and 2, 30 patients (26.5%) were lost to follow-up before primaquine initiation. CONCLUSIONS: In patients treated for P. vivax infection, G6PD activity did not vary over time. Therefore, G6PD activity on D1 instead of D14 could be used for primaquine dose-adjustment. This could allow earlier radical treatment with primaquine, that could have a public health impact by decreasing early recurrences and patients lost to follow-up before primaquine initiation. This hypothesis needs to be confirmed in larger prospective studies.

A nanochitosan-D-galactose formulation increases the accumulation of primaquine in the liver.

Primaquine is the mainstream antimalarial drug to prevent Plasmodium vivax relapses. However, this drug can induce hemolysis in patients with glucose-6-phosphate dehydrogenase deficiency. Nanostructure formulations of primaquine loaded with D-galactose were used as a strategy to target the drug to the liver and decrease the hemolytic risks. Nanoemulsion (NE-Pq) and nanochitosan (NQ-Pq) formulations of primaquine diphosphate containing D-galactose were prepared and characterized by their physicochemistry properties. Pharmacokinetic and biodistribution studies were conducted using Swiss Webster mice. A single dose of 10 mg/kg of each nanoformulation or free primaquine solution was administered by gavage to the animals, which were killed at 0.5, 1, 2, 4, 8, and 24 hours. Blood samples and tissues were collected, processed, and analyzed by high-performance liquid chromatography. The nanoformulation showed sizes around 200 nm (NE-Pq) and 400 nm (NQ-Pq) and physicochemical stability for over 30 days. Free primaquine solution achieved higher primaquine Cmax in the liver than NE-Pq or NQ-Pq at 0.5 hours. However, the half-life and mean residence time (MRT) of primaquine in the liver were three times higher with the NQ-Pq formulation than with free primaquine, and the volume distribution was four times higher. Conversely, primaquine's half-life, MRT, and volume distribution in the plasma were lower for NQ-Pq than for free primaquine. NE-Pq, on the other hand, accumulated more in the lungs but not in the liver. Galactose-coated primaquine nanochitosan formulation showed increased drug targeting to the liver compared to free primaquine and may represent a promising strategy for a more efficient and safer radical cure for vivax malaria.

Genetic basis and spatial distribution of glucose-6-phosphate dehydrogenase deficiency in ecuadorian ethnic groups: a malaria perspective.

BACKGROUND: Glucose-6-phosphate dehydrogenase deficiency (G6PDd) is an X-linked disorder affecting over 400 million people worldwide. Individuals with molecular variants associated with reduced enzymatic activity are susceptible to oxidative stress in red blood cells, thereby increasing the risk of pathophysiological conditions and toxicity to anti-malarial treatments. Globally, the prevalence of G6PDd varies among populations. Accordingly, this study aims to characterize G6PDd distribution within the Ecuadorian population and to describe the spatial distribution of reported malaria cases. METHODS: Molecular variants associated with G6PDd were genotyped in 581 individuals from Afro-Ecuadorian, Indigenous, Mestizo, and Montubio ethnic groups. Additionally, spatial analysis was conducted to identify significant malaria clusters with high incidence rates across Ecuador, using data collected from 2010 to 2021. RESULTS: The A- c.202G > A and A- c.968T > C variants underpin the genetic basis of G6PDd in the studied population. The overall prevalence of G6PDd was 4.6% in the entire population. However, this frequency increased to 19.2% among Afro-Ecuadorian people. Spatial analysis revealed 12 malaria clusters, primarily located in the north of the country and its Amazon region, with relative risks of infection of 2.02 to 87.88. CONCLUSIONS: The findings of this study hold significant implications for public health interventions, treatment strategies, and targeted efforts to mitigate the burden of malaria in Ecuador. The high prevalence of G6PDd among Afro-Ecuadorian groups in the northern endemic areas necessitates the development of comprehensive malaria eradication strategies tailored to this geographical region.

An Overall View of the Functional and Structural Characterization of Glucose-6-Phosphate Dehydrogenase Variants in the Mexican Population.

Glucose-6-phosphate dehydrogenase (G6PD) deficiency, affecting an estimated 500 million people worldwide, is a genetic disorder that causes human enzymopathies. Biochemical and genetic studies have identified several variants that produce different ranges of phenotypes; thus, depending on its severity, this enzymopathy is classified from the mildest (Class IV) to the most severe (Class I). Therefore, understanding the correlation between the mutation sites of G6PD and the resulting phenotype greatly enhances the current knowledge of enzymopathies' phenotypic and genotypic heterogeneity, which will assist both clinical diagnoses and personalized treatments for patients with G6PD deficiency. In this review, we analyzed and compared the structural and functional data from 21 characterized G6PD variants found in the Mexican population that we previously characterized. In order to contribute to the knowledge regarding the function and structure of the variants associated with G6PD deficiency, this review aimed to determine the molecular basis of G6PD and identify how these mutations could impact the structure, stability, and function of the enzyme and its relation with the clinical manifestations of this disease.

Association of CYP2C19, CYP2D6 and CYP3A4 Genetic Variants on Primaquine Hemolysis in G6PD-Deficient Patients.

In the Amazon, the treatment for Plasmodium vivax is chloroquine plus primaquine. However, this regimen is limited due to the risk of acute hemolytic anemia in glucose-6-phosphate dehydrogenase deficiency. Primaquine is a prodrug that requires conversion by the CYP2D6 enzyme to be effective against malaria. A series of cases were performed at an infectious diseases reference hospital in the Western Brazilian Amazon. The STANDARD G6PD (SD Biosensor®) assay was used to infer G6PD status and real-time PCR to genotype G6PD, CYP2C19, CYP2D6 and CYP3A4. Eighteen patients were included, of which 55.6% had African A- variant (G202A/A376G), 11.1% African A+ variant (A376G), 5.6% Mediterranean variant (C563T) and 27.8% were wild type. CYP2C19, CYP2D6 and CYP3A4 genotyping showed no statistically significant differences in the frequency of star alleles between the groups G6PD deficient and G6PD normal. Elevated levels of liver and kidney markers in the G6PDd patients were observed in gNM, gRM and gUM of CYP2C19 and CYP2D6 (p < 0.05). Furthermore, in this study there was no influence of CYPs on hemolysis. These findings reinforce the importance of studies on the mapping of G6PD deficiency and genetic variations of CYP2C19, CYP2D6 and CYP3A4. This mapping will allow us to validate the prevalence of CYPs and determine their influence on hemolysis in patients with malaria, helping to decide on the treatment regimen.

Nitazoxanide Inhibits the Bifunctional Enzyme GlG6PD::6PGL of Giardia lamblia: Biochemical and In Silico Characterization of a New Druggable Target.

Giardiasis, which is caused by Giardia lamblia infection, is a relevant cause of morbidity and mortality worldwide. Because no vaccines are currently available to treat giardiasis, chemotherapeutic drugs are the main options for controlling infection. Evidence has shown that the nitro drug nitazoxanide (NTZ) is a commonly prescribed treatment for giardiasis; however, the mechanisms underlying NTZ's antigiardial activity are not well-understood. Herein, we identified the glucose-6-phosphate::6-phosphogluconate dehydrogenase (GlG6PD::6PGL) fused enzyme as a nitazoxanide target, as NTZ behaves as a GlG6PD::6PGL catalytic inhibitor. Furthermore, fluorescence assays suggest alterations in the stability of GlG6PD::6PGL protein, whereas the results indicate a loss of catalytic activity due to conformational and folding changes. Molecular docking and dynamic simulation studies suggest a model of NTZ binding on the active site of the G6PD domain and near the structural NADP+ binding site. The findings of this study provide a novel mechanistic basis and strategy for the antigiardial activity of the NTZ drug.

Ancestry, diversity, and genetics of health-related traits in African-derived communities (quilombos) from Brazil.

Brazilian quilombos are communities formed by enslaved Africans and their descendants all over the country during slavery and shortly after its abolition. Quilombos harbor a great fraction of the largely unknown genetic diversity of the African diaspora in Brazil. Thus, genetic studies in quilombos have the potential to provide important insights not only into the African roots of the Brazilian population but also into the genetic bases of complex traits and human adaptation to diverse environments. This review summarizes the main results of genetic studies performed on quilombos so far. Here, we analyzed the patterns of African, Amerindian, European, and subcontinental ancestry (within Africa) of quilombos from the five different geographic regions of Brazil. In addition, uniparental markers (from the mtDNA and the Y chromosome) studies are analyzed together to reveal demographic processes and sex-biased admixture that occurred during the formation of these unique populations. Lastly, the prevalence of known malaria-adaptive African mutations and other African-specific variants discovered in quilombos, as well as the genetic bases of health-related traits, are discussed here, together with their implication for the health of populations of African descent.

Deficiência de GDPD: um relato de caso / GDPD deficiency: a case report

INTRODUÇÃO: A deficiência da enzima G6PD afeta cerca de 400 milhões de pessoas no mundo. É uma doença autossômica ligada ao cromossomo X. A G6PD é uma enzima que desempenha um papel na prevenção de danos celulares causados por espécies reativas de oxigênio, evitando o estresse oxidativo. Após serem expostas a um agente exógeno portadores da deficiência de G6PD podem apresentar uma anemia hemolítica aguda, podendo até ser fatal. O caso relatado neste trabalho é de uma paciente que durante quatro anos buscou auxílio diagnóstico na rede básica de saúde por diversas ocasiões, recebendo o diagnóstico de deficiência de G6PD após investigação minuciosa durante o período de internação. OBJETIVO: O relato de caso de um diagnóstico desafiador na prática médica de uma condição que apesar de comum ainda é de difícil diagnóstico, principalmente quando apresentado sintomas na fase adulta. MÉTODOS: Esse foi um estudo do tipo relato de caso, em que se descreveu um caso de deficiência da enzima G6PD. Realizada pesquisa bibliográfica utilizando como complementação bibliográfica e embasamento teórico. RESULTADOS/DISCUSSÃO: Após intensa investigação e correlação com o quadro clínico, foi evidenciado níveis séricos reduzidos de G6PD, sendo estabelecido quadro de deficiência de G6PD. que também pode ter gerado um atraso no diagnóstico foi o fato da patologia psiquiátrica importante da paciente. É sabido que os paciente psiquiátricos são muitas vezes negligenciados pela equipe de saúde, sempre atribuindo todos os sintomas ao quadro psiquiátrico. CONCLUSÃO: A deficiência de G6PD é um diagnóstico desafiador na prática médica, e apesar de comum é subdiagnosticada, visto que é pouco aventada como etiologia de um quadro sistêmico, principalmente quando apresenta sintomas apenas na fase adulta, em especial, pacientes com transtornos psiquiátricos.

Quantitative G6PD Deficiency Screening in Routine Malaria Diagnostic Units in the Brazilian Amazon (SAFEPRIM): An Operational Mixed-Methods Study.

BACKGROUND: Glucose-6-phosphate dehydrogenase (G6PD) deficiency testing is not routinely performed before primaquine treatment in most Plasmodium vivax endemic areas, despite the risk of primaquine-associated hemolysis. This is due to the operational challenges associated with pragmatic G6PD testing and as such needs to be addressed. METHODS AND FINDINGS: This mixed-methods operational study was aimed at implementing the quantitative point-of-care StandardTM G6PD (SD Biosensor, Korea) screening test in malaria treatment units (MTUs) in the municipalities of Rio Preto da Eva and Mâncio Lima, in the Brazilian Amazon, between mid-January 2020 and December 2020. In total, 1286 P. vivax cases were treated based on the Standard G6PD test: 1230 had activity equal to or greater than 4.0 U/g Hb, and 56 less than 4.0 U/g Hb. No G6PD deficient (G6PDd) genotypes were found in 96 samples from the 1230, and only 21 of the 56 G6PDd cases had confirmed G6PDd genotypes. Evaluations were conducted on the proficiency of health care professionals (HCPs) training to perform the test, the reliability of testing performed in the field, and the perceptions of HCPs and patients about the implementation. Post-training proficiency was 73.4% after a 4-hour training session. This study revealed that locations with lower malaria caseloads will need regular refresher training. The test was well accepted by both HCPs and patients. Signs and symptoms of hemolysis were not always associated with malaria treatment drugs by HCPs and patients. INTERPRETATION: Point-of-care quantitative G6PD testing can be performed at MTUs in the Brazilian Amazon to inform treatment decisions with primaquine. Limitations related to technical and cultural aspects need to be addressed further when expanding screening to larger areas.

Functional characterization of the p.(Gln195His) or Tainan and novel p.(Ser184Cys) or Toluca glucose-6-phosphate dehydrogenase (G6PD) gene natural variants identified through Mexican newborn screening for glucose-6-phosphate dehydrogenase deficiency.

BACKGROUND: Newborn screening for glucose-6-phosphate dehydrogenase deficiency (G6PDd) was implemented in Mexico beginning in 2017. In a Mexican population, genotyping analysis of G6PD as a second-tier method identified a previously unreported missense variant, p.(Ser184Cys), which we propose to call "Toluca", and the extremely rare p.(Gln195His) or "Tainan" variant, which was previously described in the Taiwanese population as a Class II allele through in silico evaluations. Here, we sought to perform in vitro biochemical characterizations of the Toluca and Tainan G6PD natural variants and describe their associated phenotypes. METHODS: The "Toluca" and "Tainan" variants were identified in three unrelated G6PDd newborn males, two of whom lacked evidence of acute hemolytic anemia (AHA) or neonatal hyperbilirubinemia (NHB). We constructed wild-type (WT), Tainan, and Toluca G6PD recombinant enzymes and performed in vitro assessments. RESULTS: Both variants had diminished G6PD expression, decreased affinities for glucose-6-phosphate and NADP+ substrates, significant decreases in catalytic efficiency (∼97 % with respect to WT-G6PD), and diminished thermostabilities that were partially rescued by NADP+. In silico protein modeling predicted that the variants would have destabilizing effects on the protein tertiary structure, potentially reducing the enzyme half-lives and/or catalytic efficiencies. CONCLUSION: Our data suggest that G6PD "Tainan" and "Toluca" are potential Class II natural variants, which agrees with the absence of chronic nonspherocytic hemolytic anemia (CNSHA) in our patients. It remains to be determined whether these variants represent high-risk genetic factors for developing CNSHA, AHA, and/or NHB.

Duffy blood system and G6PD genetic variants in vivax malaria patients from Manaus, Amazonas, Brazil.

BACKGROUND: Over a third of the world's population is at risk of Plasmodium vivax-induced malaria. The unique aspect of the parasite's biology and interactions with the human host make it harder to control and eliminate the disease. Glucose-6-phosphate dehydrogenase (G6PD) deficiency and Duffy-negative blood groups are two red blood cell (RBC) variations that can confer protection against malaria. METHODS: Molecular genotyping of G6PD and Duffy variants was performed in 225 unrelated patients (97 with uncomplicated and 128 with severe vivax malaria) recruited at a Reference Centre for Infectious Diseases in Manaus. G6PD and Duffy variants characterizations were performed using Real Time PCR (qPCR) and PCR-RFLP, respectively. RESULTS: The Duffy blood group system showed a phenotypic distribution Fy(a + b-) of 70 (31.1%), Fy(a + b +) 96 (42.7%), Fy(a-b +) 56 (24.9%) and Fy(a-b-) 1 (0.44%.) The genotype FY*A/FY*B was predominant in both uncomplicated (45.3%) and severe malaria (39.2%). Only one Duffy phenotype Fy(a-b) was found and this involved uncomplicated vivax malaria. The G6PD c.202G > A variant was found in 11 (4.88%) females and 18 (8.0%) males, while c.376A > G was found in 20 females (8.88%) and 23 (10.22%) male patients. When combined GATA mutated and c.202G > A and c.376A > G mutated, was observed at a lower frequency in uncomplicated (3.7%) in comparison to severe malaria (37.9%). The phenotype Fy(a-b +) (p = 0.022) with FY*B/FY*B (p = 0.015) genotype correlated with higher parasitaemia. CONCLUSIONS: A high prevalence of G6PD c202G > A and c.376A > G and Duffy variants is observed in Manaus, an endemic area for vivax malaria. In addition, this study reports for the first time the Duffy null phenotype Fy(a-b-) in the population of the Amazonas state. Moreover, it is understood that the relationship between G6PD and Duffy variants can modify clinical symptoms in malaria caused by P. vivax and this deserves to be further investigated and explored among this population.

COVID-19 in G6PD-deficient Patients, Oxidative Stress, and Neuropathology.

Glucose-6-phosphate dehydrogenase (G6PD) is an enzyme that regulates energy metabolism mainly through the pentose phosphate pathway (PPP). It is well known that this enzyme participates in the antioxidant/oxidant balance via the synthesis of energy-rich molecules: nicotinamide adenine dinucleotide phosphate reduced (NADPH), the reduced form of flavin adenine dinucleotide (FADH) and glutathione (GSH), controlling reactive oxygen species generation. Coronavirus disease 19 (COVID-19), induced by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is a public health problem that has caused approximately 4.5 million deaths since December 2019. Concerning the role of G6PD in COVID-19 development, it is known from the existing literature that G6PD-deficient patients infected with SARS-CoV-2 are more susceptible to thrombosis and hemolysis, suggesting that G6PD deficiency facilitates infection by SARS-CoV-2. Concerning G6PD and neuropathology, it has been observed that deficiency of this enzyme is also present with an increase in oxidative markers. Concerning the role of G6PD and the neurological manifestations of COVID-19, it has been reported that the enzymatic deficiency in patients infected with SARSCoV- 2 exacerbates the disease, and, in some clinical reports, an increase in hemolysis and thrombosis was observed when patients were treated with hydroxychloroquine (OH-CQ), a drug with oxidative properties. In the present work, we summarize the evidence of the role of G6PD in COVID- 19 and its possible role in the generation of oxidative stress and glucose metabolism deficits, and inflammation present in this respiratory disease and its progression including neurological manifestations.

Kinetic and Molecular Docking Studies to Determine the Effect of Inhibitors on the Activity and Structure of Fused G6PD::6PGL Protein from Trichomonas vaginalis.

Trichomoniasis is a sexually transmitted disease with a high incidence worldwide, affecting 270 million people. Despite the existence of a catalog of available drugs to combat this infection, their extensive use promotes the appearance of resistant Trichomonas vaginalis (T. vaginalis), and some side effects in treated people, which are reasons why it is necessary to find new alternatives to combat this infection. In this study, we investigated the impact of an in-house library comprising 55 compounds on the activity of the fused T. vaginalis G6PD::6PGL (TvG6PD::6PGL) protein, a protein mediating the first reaction step of the pentose phosphate pathway (PPP), a crucial pathway involved in the parasite's energy production. We found four compounds: JMM-3, CNZ-3, CNZ-17, and MCC-7, which inhibited the TvG6PD::6PGL protein by more than 50%. Furthermore, we determined the IC50, the inactivation constants, and the type of inhibition. Our results showed that these inhibitors induced catalytic function loss of the TvG6PD::6PGL enzyme by altering its secondary and tertiary structures. Finally, molecular docking was performed for the best inhibitors, JMM-3 and MCC-7. All our findings demonstrate the potential role of these selected hit compounds as TvG6PD::6PGL enzyme selective inhibitors.

Prevalence of glucose 6-phosphate dehydrogenase deficiency in highly malaria-endemic municipalities in the Brazilian Amazon: A region-wide screening study.

Background: Difficulties associated with the assessment of glucose-6-phosphate dehydrogenase deficiency (G6PDd), particularly in remote areas, hinders the safe use of 8-aminoquinolines such as primaquine (PQ) and tafenoquine against Plasmodium vivax malaria due to the risk of haemolysis. Methods: This cross-sectional study was conducted in 41 malaria-endemic municipalities of six states in the Brazilian Amazon, between 2014 and 2018. Male individuals were screened for G6PDd using the qualitative Fluorescent Spot Test using fingerpick-collected whole blood samples. Point and interval estimates of the G6PDd prevalence were calculated for each state. Deficient samples were genotyped for the most prevalent variants in the Amazon. Frequencies of P. vivax malaria recurrences were estimated for G6PDd and non-G6PDd patients. Interpretation: This is one of the largest surveys ever conducted in Latin America, covering the entire malaria endemic area in the Brazilian Amazon. These results indicate that an important proportion of the population is at risk of hemolysis if exposed to PQ and its congener drug tafenoquine. The adoption of G6PDd screening protocols is essential to ensure the safety of individuals treated with those drugs and should also be considered when implementing malaria elimination strategies. Findings: A total of 14,847 individuals were included, of which 5.6% presented G6PDd. The state of Acre had the highest G6PDd prevalence (8.3%), followed by Amapá (5.8%), Pará (5.7%), Rondônia (5.4%), Roraima (4.2%) and Amazonas (4.0%). From 828 genotyped samples, African A+ (6.2%), African A- (39.3%) and wild-type (non-African non-Mediterranean; 54.2%) variants were found. A greater proportion of malaria recurrences was found among G6PD deficient individuals [16.7% vs 4.1%, Risk ratio 3.52 (2.16-5.74) p < 0.01]. Funding: Brazilian Ministry of Health; Fundação de Amparo à Pesquisa do Estado do Amazonas (FAPEAM).

Hematological and molecular analysis of patients with G6PD deficiency revealed coexistent hereditary spherocytosis and alpha thalassemia.

BACKGROUND: Glucose-6-phosphate dehydrogenase (G6PD) deficiency, hereditary spherocytosis (HS), and alpha thalassemia (α-thal) are frequent erythrocyte pathologies with different geographic distributions worldwide. Our aim is to report hematological and molecular findings of G6PD deficient Mexican patients in coinheritance with suggestive hereditary spherocytosis (sHS) and α-thal. METHODS: We studied 78 G6PD deficiency patients. Hematological parameters, acidified glycerol lysis test, erythrocyte morphology, electrophoresis, and hemoglobin quantification were obtained. G6PD and HBA2/HBA1 variants were identified using ARMS-PCR, Gap-PCR, or Sanger sequencing. RESULTS: Nine G6PD variants were identified; A-202A/376G , A-376G/968C , and A+376G as the most frequent. G6PD Santiago de Cuba1339A and Kamiube1387T were detected in Mexicans for first time. Hematological analysis revealed additional erythrocyte pathologies in 52 patients, 32 with positive osmotic fragility test and spherocytes in blood smear (suggestive hereditary spherocytosis, sHS), 12 with microcytosis and 8 with all three defects who had the most severe phenotype, with significantly lower hematological parameters (Hb, PCV, MCV, and MCH). α-thal variants (αHph α, α-59C>T α and -α3.7 ) were observed in 65% of patients with microcytosis. CONCLUSION: Additional erythrocyte defects were observed in 69.3% of G6PD deficiency patients. We stress the importance of searching for the presence of additional erythrocyte hereditary diseases in patients with G6PD deficiency.

Effect of weekly versus daily primaquine on Plasmodium vivax malaria recurrences: A real-life cohort study

ABSTRACT Background: Although primaquine (PQ) is indicated for G6PD-deficient patients, data on weekly PQ use in Brazil are limited. Methods: We aimed to investigate malaria recurrences among participants receiving daily and weekly PQ treatments in a real-life setting of two municipalities in the Amazon between 2019 and 2020. Results: Patients receiving weekly PQ treatment had a lower risk of recurrence than those receiving daily PQ treatment (risk ratio: 0.62, 95% confidence interval: 0.41-0.94), using a model adjusted for study site. Conclusions: Weekly PQ use did not increase the risk of malaria recurrence. Further studies with larger populations are warranted.

Usability of a point-of-care diagnostic to identify glucose-6-phosphate dehydrogenase deficiency: a multi-country assessment of test label comprehension and results interpretation.

BACKGROUND: Point-of-care glucose-6-phosphate dehydrogenase (G6PD) testing has the potential to make the use of radical treatment for vivax malaria safer and more effective. Widespread use of G6PD tests as part of malaria case management has been limited, in part due to due concerns regarding product usability, user training, and supervision. This study seeks to assess how well end users can understand the Standard™ G6PD Test (SD Biosensor, Suwon, South Korea) workflow, result output, and label after training. This will ultimately help inform test registration and introduction. METHODS: Potential G6PD test users who provide malaria case management at three sites in Brazil, Ethiopia, and India were trained on the use of the SD Biosensor Standard G6PD Test and assessed based on their ability to understand the test workflow and interpret results. The assessment was done through a questionnaire, designed to assess product usability against key technical product specifications and fulfill regulatory evidence requirements. Any participant who obtained 85% or above correct responses to the questionnaire was considered to adequately comprehend how to use and interpret the test. RESULTS: Forty-five participants, including malaria microscopists, laboratory staff, nurses, and community health workers took part in the study. Seventy-eight percent of all participants in the study (35/45) obtained passing scores on the assessment with minimal training. Responses to the multiple-choice questions indicate that most participants understood well the test intended use, safety claims, and warnings. The greatest source of error regarding the test was around the correct operating temperature. Most test results were also read and interpreted correctly, with the haemoglobin measurement being a more problematic output to interpret than the G6PD measurement. CONCLUSIONS: These data results show how a standardized tool can be used to assess a user's ability to run a point-of-care diagnostic and interpret results. When applied to the SD Biosensor Standard G6PD Test, this tool demonstrates that a range of users across multiple contexts can use the test and suggests improvements to the test instructions and training that can improve product usability, increase user comprehension, and ultimately contribute to more widespread effective use of point-of-care G6PD tests. TRIAL REGISTRATION: NCT04033640.

Genetic spectrum and clinical early natural history of glucose-6-phosphate dehydrogenase deficiency in Mexican children detected through newborn screening.

BACKGROUND: Glucose-6-phosphate dehydrogenase deficiency (G6PDd) newborn screening is still a matter of debate due to its highly heterogeneous birth prevalence and clinical expression, as well as, the lack of enough knowledge on its natural history. Herein, we describe the early natural clinical course and the underlying GDPD genotypes in infants with G6PDd detected by newborn screening and later studied in a single follow-up center. G6PDd newborns were categorized into three groups: group 1: hospitalized with or without neonatal jaundice (NNJ); group 2: non-hospitalized with NNJ; and group 3: asymptomatic. Frequencies of homozygous UGT1A1*28 (rs34983651) genotypes among G6PDd patients with or without NNJ were also explored. RESULTS: A total of 81 newborns (80 males, one female) were included. Most individuals (46.9%) had NNJ without other symptoms, followed by asymptomatic (42.0%) and hospitalized (11.1%) patients, although the hospitalization of only 3 of these patients was related to G6PDd, including NNJ or acute hemolytic anemia (AHA). Nine different G6PDd genotypes were found; the G6PD A-202A/376G genotype was the most frequent (60.5%), followed by the G6PD A-376G/968C (22.2%) and the Union-Maewo (rs398123546, 7.4%) genotypes. These genotypes produce a wide range of clinical and biochemical phenotypes with significant overlapping residual enzymatic activity values among class I, II or III variants. Some G6PD A-202A/376G individuals had enzymatic values that were close to the cutoff value (5.3 U/g Hb, 4.6 and 4.8 U/g Hb in the groups with and without NNJ, respectively), while others showed extremely low enzymatic values (1.1 U/g Hb and 1.4 U/g Hb in the groups with and without NNJ, respectively). Homozygosity for UGT1A1*28 among G6PDd patients with (11.9%, N = 5/42) or without (10.3%, N = 4/39) NNJ did not shown significant statistical difference (p = 0.611). CONCLUSION: Wide variability in residual enzymatic activity was noted in G6PDd individuals with the same G6PD genotype. This feature, along with a documented heterogeneous mutational spectrum, makes it difficult to categorize G6PD variants according to current WHO classification and precludes the prediction of complications such as AHA, which can occur even with > 10% of residual enzymatic activity and/or be associated with the common and mild G6PD A-376G/968C and G6PD A-202A/376G haplotypes.