Prevalence and molecular characterization of G6PD deficiency in two Plasmodium vivax endemic areas in Venezuela: predominance of the African A-(202A/376G) variant

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.

Epidemiological and clinical characteristics of patients with malaria admitted to a hospital in Mérida, Venezuela

BACKGROUND

Malaria is expanding rapidly across Venezuela, spreading outwards from traditional high transmission regions in the southeast of the country, but the lack of official data make it impossible to understand the reasons for this expansion and to estimate its real magnitude. This study aims to evaluate the epidemiological characteristics driving the re-emergence of malaria in Mérida, a state in the west of Venezuela, where no cases have been reported since 2003, and also to study the clinical presentation of the disease in patients presenting with malaria.

METHODS

Thirty-three patients who presented with anemia and fever and with a microscopic diagnosis of malaria were examined and interviewed. Data were collected in standardized forms and analyzed. One-way analysis of variance was used to study differences among patients infected with different parasites.

RESULTS

Twenty-two patients were from the Zulia state and eleven were from the Mérida state, mainly from the lowlands south of Lake Maracaibo. Six of these patients traveled to the Bolívar state between 2017 and 2019. Thirteen patients presented with the WHO criteria for severe malaria.Conclusions:Domestic migration to the southeast of Venezuela may have played an important role in the expansion of malaria in previously existing endemic areas of transmission and also in the increase in the number of cases of severe malaria.

First report of glucose-6-phosphate dehydrogenase (G6PD) variants (Mahidol and Acores) from malaria-endemic regions of northeast India and their functional evaluations in-silico

G6PD deficiency results from numerous mutations in the G6PD gene and can cause alterations in enzyme function up to varying degrees. P. vivax malaria infections require G6PD deficiency screening because of the potential risk of haemolysis by the gametocytocidal drug (primaquine) during the radical treatment. The present study investigated the incidence of G6PD deficiency from northeast India and further, molecular characterization was performed. During 2014-16, a total of 1,015 patients from four north-eastern states of India (Tripura, Mizoram, Meghalaya & Arunachal Pradesh), were screened for G6PD deficiency, using Beutler's fluorescence spot test (FST) and confirmed with SPAN G6PD kit. The deficient individuals (55/1015, 5.4%) were further characterized by PCR-RFLP and DNA sequencing except one case of lost to follow up. As observed by FST, the frequency of G6PD deficient males (42/538, 7.8%) were found to be higher than females (13/477, 2.73%), (p < 0.0001). Two non-synonymous mutations; G6PD-D (Mahidol)^487A (48/54, 88.9%; 36 hemizygous males, 8 homozygous and 4 heterozygous females) and G6PD-D (Acores)^595T (2/54, 3.7%) were identified. Remaining (4/54, 7.4%) individuals could not be characterized. Molecular modeling and dynamic simulations were performed for the G6PD wild-type (G6PD-WT) enzyme and its variants. The in-silico results demonstrated alterations in the secondary structures & crucial loss of ligand-protein interactions, which might result in reduced enzyme function, leading to enzyme deficiency. To the best of our knowledge, this is the first report to document G6PD-Mahidol and G6PD-Acores variants from malaria-endemic regions of northeast India, and provided molecular insights on the varied genetic makeup of the studied population.

The association between glucose-6-phosphate dehydrogenase deficiency and abnormal blood pressure among prepregnant reproductive-age Chinese females

The morbidity of hypertension is increasing among young adults worldwide, and glucose-6-phosphate dehydrogenase (G6PD) deficiency is a high-prevalence genetic disease. We investigated whether G6PD deficiency was associated with abnormal blood pressure (including elevated blood pressure and hypertension) among prepregnant reproductive-age females. We conducted a cross-sectional study in Shenzhen, which included 154 917 females aged 20-49 who participated in the National Free Pre-conception Check-up Projects supported by the Chinese government. After adjusting for confounding factors, the odds ratios (ORs) for the effects of G6PD deficiency on elevated blood pressure and hypertension were 1.18 (95% confidence interval (CI): 1.03-1.35) and 1.11 (95% CI: 1.00-1.23), respectively. Moreover, the association between G6PD deficiency and abnormal blood pressure was statistically significant for systolic blood pressure (SBP) but not significant for diastolic blood pressure (DBP). The multivariable-adjusted ORs for females with G6PD deficiency in the SBP 120-139 mm Hg and SBP ≥ 140 mm Hg groups were 1.10 (95% CI: 1.00-1.21) and 1.75 (95% CI: 1.25-2.42), respectively, while the multivariable-adjusted ORs for females with G6PD deficiency in the DBP 80-89 mm Hg and DBP ≥ 90 mm Hg groups were 1.09 (95% CI: 0.98-1.21) and 0.89 (95% CI: 0.66-1.19), respectively. Subgroup analyses showed similar results. The findings of this study underscored that reproductive-age females with a G6PD deficiency had a higher risk of elevated blood pressure and hypertension. Therefore, females with G6PD deficiency combined with elevated blood pressure or hypertension were high-risk populations during prepregnancy and pregnancy periods. Early intervention and collaborative management approaches should be explored to reduce the burden of these two diseases and improve maternal and child health.

Molecular genotyping of G6PD mutations and Duffy blood group in Afro-descendant communities from Brazilian Amazon

Glucose-6-phosphate dehydrogenase deficiency (G6PDd) and Duffy-negative blood group are two red blood cells variants that confer protection against malaria. In this study, the distribution of the most common G6PD variants (G6PD*A-, GGPD*A and G6PD Mediterranean) and the major alleles of the Duffy blood group (FY*A, FY*B and FY*BES) were investigated in an Afro-descendant population from state of Pará, Brazilian Amazon. G6PD variants and Duffy blood group alleles were determined by TaqMan SNP genotyping assay. Overall, molecular genotyping revealed the presence of G6PD variants in 126 (24%) of the individuals studied (5% male and 19% female), and frequencies of the G6PD*A- and G6PD*A alleles were 0.061 and 0.104, respectively. Duffy blood group genotyping showed that 24.3% of people were Duffy-negative and 41.3% were heterozygous for FY*BES. The frequency of allele FY*BES was 41.0%. The results emphasize the need to monitor G6PD deficiency for the use of primaquine in the routine care of the Afro-descendant communities of the Trombetas, Erepecuru and Cumná rivers, evaluating the risks of hemolytic crisis in case of recurrence of malaria in the region. In addition, the possible greater protection against malaria conferred by these erythrocyte polymorphisms deserves to be better investigated and explored among these Afro-descendants.

Role of genetic factors and ethnicity on the multiplicity of Plasmodium falciparum infection in children with asymptomatic malaria in Yaoundé, Cameroon

In this cross-sectional study, we investigated host genetic factors and ethnic variation in circulating Plasmodium falciparum merozoite surface protein 2 (msp-2) clones among children with asymptomatic malaria. Isolates from seventy two asymptomatic malaria children were used for genotyping block 3 of msp-2 gene by nested polymerase chain reaction (PCR). Sickle cell trait and glucose-6-phosphate dehydrogenase (G6PD) deficiency were analysed by restriction fragment length polymorphism of DNA products from PCR targeting codons 6 and 68 of the beta-globin (HBB) and G6PD genes respectively. ABO blood group was typed by agglutination method. A total of forty two msp-2 genotypes (20 for 3D7 and 22 for FC27) were detected for an average (standard error of mean) multiplicity of infection (MOI) of 2.45 (0.16). The MOI was statistically the same among the five identified ethnic groups (P = 0.83). The overall prevalence of sickle cell trait and G6PD deficiency were 12.50 % and 22.22 % respectively. MOI was similar between children with Hb AA and Hb AS genotypes (P = 0.42). MOI was significantly high among children with a mutant G6PD genotype (P = 0.017). MOI was significantly higher in blood group O than group A (P = 0.03). Our findings show that although ethnicity and sickle cell trait have no association with MOI, the association was observed with G6PD genotype and ABO group. The results suggest the need for extension and expansion of the current study in order to investigate the mechanisms involved.

Use of primaquine and glucose-6-phosphate dehydrogenase deficiency testing: Divergent policies and practices in malaria endemic countries

Primaquine is the only available antimalarial drug that kills dormant liver stages of Plasmodium vivax and Plasmodium ovale malarias and therefore prevents their relapse (‘radical cure’). It is also the only generally available antimalarial that rapidly sterilises mature P. falciparum gametocytes. Radical cure requires extended courses of primaquine (usually 14 days; total dose 3.5–7 mg/kg), whereas transmissibility reduction in falciparum malaria requires a single dose (formerly 0.75 mg/kg, now a single low dose [SLD] of 0.25 mg/kg is recommended). The main adverse effect of primaquine is dose-dependent haemolysis in glucose 6-phosphate dehydrogenase (G6PD) deficiency, the most common human enzymopathy. X-linked mutations conferring varying degrees of G6PD deficiency are prevalent throughout malaria-endemic regions. Phenotypic screening tests usually detect <30% of normal G6PD activity, identifying nearly all male hemizygotes and female homozygotes and some heterozygotes. Unfortunately, G6PD deficiency screening is usually unavailable at point of care, and, as a consequence, radical cure is greatly underused. Both haemolytic risk (determined by the prevalence and severity of G6PD deficiency polymorphisms) and relapse rates vary, so there has been considerable uncertainty in both policies and practices related to G6PD deficiency testing and use of primaquine for radical cure. Review of available information on the prevalence and severity of G6PD variants together with countries’ policies for the use of primaquine and G6PD deficiency testing confirms a wide range of practices. There remains lack of consensus on the requirement for G6PD deficiency testing before prescribing primaquine radical cure regimens. Despite substantially lower haemolytic risks, implementation of SLD primaquine as a P. falciparum gametocytocide also varies. In Africa, a few countries have recently adopted SLD primaquine, yet many with areas of low seasonal transmission do not use primaquine as an antimalarial at all. Most countries that recommended the higher 0.75 mg/kg single primaquine dose for falciparum malaria (e.g., most countries in the Americas) have not changed their recommendation. Some vivax malaria–endemic countries where G6PD deficiency testing is generally unavailable have adopted the once-weekly radical cure regimen (0.75 mg/kg/week for 8 weeks), known to be safer in less severe G6PD deficiency variants. There is substantial room for improvement in radical cure policies and practices.

Malaria in Brazil, Colombia, Peru and Venezuela: current challenges in malaria control and elimination

In spite of significant progress towards malaria control and elimination achieved in South America in the 2000s, this mosquito-transmitted tropical disease remains an important public health concern in the region. Most malaria cases in South America come from Amazon rain forest areas in northern countries, where more than half of malaria is caused by Plasmodium vivax, while Plasmodium falciparum malaria incidence has decreased in recent years. This review discusses current malaria data, policies and challenges in four South American Amazon countries: Brazil, Colombia, Peru and the Bolivarian Republic of Venezuela. Challenges to continuing efforts to further decrease malaria incidence in this region include: a significant increase in malaria cases in recent years in Venezuela, evidence of submicroscopic and asymptomatic infections, peri-urban malaria, gold mining-related malaria, malaria in pregnancy, glucose-6-phosphate dehydrogenase (G6PD) deficiency and primaquine use, and possible under-detection of Plasmodium malariae. Some of these challenges underscore the need to implement appropriate tools and procedures in specific regions, such as a field-compatible molecular malaria test, a P. malariae-specific test, malaria diagnosis and appropriate treatment as part of regular antenatal care visits, G6PD test before primaquine administration for P. vivax cases (with weekly primaquine regimen for G6PD deficient individuals), single low dose of primaquine for P. falciparum malaria in Colombia, and national and regional efforts to contain malaria spread in Venezuela urgently needed especially in mining areas. Joint efforts and commitment towards malaria control and elimination should be strategized based on examples of successful regional malaria fighting initiatives, such as PAMAFRO and RAVREDA/AMI.

Co-inheritance of glucose-6-phosphate dehydrogenase deficiency mutations and hemoglobin E in a Kachin population in a malaria-endemic region of Southeast Asia

Glucose-6-phosphate dehydrogenase (G6PD) deficiency and hemoglobin E (HbE, β26 Glu-Lys) are two common red cell disorders in Southeast Asia. G6PD deficiency produces hemolytic anemia, which can be triggered by certain drugs or infections. HbE is asymptomatic or is manifested as microcytic, minimally hemolytic anemia. The association between G6PD deficiency and HbE is little understood. This study aimed to investigate G6PD deficiency and HbE in a Kachin ethnic group in the China-Myanmar border area. G6PD enzyme activity was measured using a quantitative G6PD assay, G6PD variants genotyped by the SNaPshot assay, and an HbE gene mutation identified by an amplification refractory mutation system and subsequently confirmed by using a reverse dot blot hybridization assay from 100 unrelated individuals in the study area. G6PD enzyme activity ranged from 0.4 to 24.7 U/g Hb, and six males had severe G6PD deficiency (<0.12-1.2 U/g Hb), while six males and 12 females had mild G6PD deficiency (>1.2-4.5 U/g Hb). Among the 24 G6PD-deficient subjects, 22 (92%) had the Mahidol 487G>A mutation (12 male hemizygotes, one female homozygote, and nine female heterozygotes), while the G6PD genotypes in two female subjects were unknown. HbE was identified in 39 subjects (20 males and 19 females), including 15 HbEE (seven males and eight females) and 24 HbAE (13 males and 11 females). Twenty-three subjects co-inherited both G6PD deficiency and HbE (22 with HbAE and one with HbEE). Whereas mean Hb levels were not significantly different between the HbA and HbE groups, G6PD-deficient males had significantly lower Hb levels than G6PD-normal males (P < 0.05, t-test). However, it is noteworthy that two G6PD-deficient hemizygous males with HbAE were severely anemic with Hb levels below 50 g/L. This study revealed high prevalence of co-inheritance of G6PD deficiency with HbAE in the Kachin ethnicity, and a potential interaction of the G6PD Mahidol 487G>A and HbAE in males leading to severe anemia. The presence of 6% males with severe G6PD deficiency raised a major concern in the use of primaquine for radical cure of vivax malaria.

Glucose-6-phosphate dehydrogenase deficiency prevalence and genetic variants in malaria endemic areas of Colombia

BACKGROUND

Glucose 6-phosphate dehydrogenase (G6PD) is an enzyme involved in prevention of cellular oxidative damage, particularly protecting erythrocytes from haemolysis. An estimated 400 million people present variable degrees of inherited G6PD deficiency (G6PDd) which puts them at risk for developing haemolysis triggered by several risk factors including multiple drugs and certain foods. Primaquine (PQ) is a widely used anti-malarial drug that can trigger haemolysis in individuals with G6PDd. Intensification of malaria control programmes worldwide and particularly malaria elimination planning in some regions recommend a more extensive use of PQ and related drugs in populations with different G6PDd prevalence. This a preliminary study to assess the prevalence of G6PDd in representative malaria endemic areas of Colombia by measuring G6PD phonotype and genotypes.

METHODS

Volunteers (n = 426) from four malaria endemic areas in Colombia (Buenaventura, Tumaco, Tierralta and Quibdo) were enrolled. Blood samples were drawn to evaluate G6PD enzymatic activity by using a quantitative G6PD test and a subset of samples was analysed by PCR-RFLP to determine the frequency of the three most common G6PD genotypic variants: A-, A+ and Mediterranean.

RESULTS

A total of 28 individuals (6.56 %) displayed either severe or intermediate G6PDd. The highest prevalence (3.51 %) was in Buenaventura, whereas G6PDd prevalence was lower (<1 %) in Tierralta and Quibdo. G6PD A alleles were the most frequent (15.23 %) particularly in Buenaventura and Tumaco. Overall, a high frequency of G6PD A- genotype, followed by A+ genotype was found in the analysed population.

CONCLUSIONS

G6PDd based on enzymatic activity as well as G6PD A allelic variants were found in malaria-endemic populations on the Pacific coast of Colombia, where most of malaria cases are caused by Plasmodium vivax infections. These infections are treated for 14 days with PQ, however there are no official reports of PQ-induced haemolytic crises. Further assessment of G6PDd prevalence in malaria endemic areas in Colombia is crucial in view of possible mass drug administration for malaria elimination in these regions, as well as implementation of appropriate G6PDd diagnostic methods.