ABO Blood Group Phenotypes and Plasmodium falciparum Malaria: Unlocking a Pivotal Mechanism

Prevalence and Association of Malaria With the Blood Group on Febrile Patients at Woldia Comprehensive Specialized Hospital, Northeast Ethiopia

Background: Malaria is a disease transmitted by vectors and caused by unicellular Plasmodium parasites. Malaria pathogenesis is associated with the ABO phenotype. However, there is little information on the frequency of malaria disease and its relationship with the ABO blood group in the study area. Therefore, the purpose of this study was to determine the prevalence of malaria infection and its association with the ABO blood group at Woldia Comprehensive Specialized Hospital. Method: An institutional-based cross-sectional study was conducted from December 3, 2022, to February 30, 2023. Convenient sampling was used for selecting the study participants. To identify malaria parasites, thick and thin blood films were made. Additionally, blood was drawn to identify the ABO blood group type. Before being analyzed with SPSS software Version 27, the data was coded and entered into EpiData Version 3.1. To ascertain the variable's association, a logistic regression was done. Results: Out of 192 patients that attended Woldia Comprehensive Specialized Hospital, 16 (8.3%) were found to be infected with Plasmodium parasites using microscopy. Among them, 9 (4.7%), 5 (2.6%), and 2 (1.0%) had Plasmodium falciparum, Plasmodium vivax, or mixed infections, respectively. As a result, 30.7%, 25.5%, 24.5%, and 19.3% of the participants had blood types A, B, AB, and O, respectively (AOR = 2.359, 95% CI: 1.03-12.289, p = 0.03). Conclusion and Recommendation: The total number of microscopically confirmed malaria parasites was 8.3%. P. falciparum was dominant over P. vivax. Individuals with blood group O were less likely to get severe malaria than those with other blood groups. Based on the findings of this study, we recommend that additional studies investigate the probable relationship between the ABO blood group phenotype and malaria infection.

Novel functions for von Willebrand factor

ABSTRACT

For many years, it has been known that von Willebrand factor (VWF) interacts with factor VIII, collagen, and platelets. In addition, the key roles played by VWF in regulating normal hemostasis have been well defined. However, accumulating recent evidence has shown that VWF can interact with a diverse array of other novel ligands. To date, over 60 different binding partners have been described, with interactions mapped to specific VWF domains in some cases. Although the biological significance of these VWF-binding interactions has not been fully elucidated, recent studies have identified some of these novel ligands as regulators of various aspects of VWF biology, including biosynthesis, proteolysis, and clearance. Conversely, VWF binding has been shown to directly affect the functional properties for some of its ligands. In keeping with those observations, exciting new roles for VWF in regulating a series of nonhemostatic biological functions have also emerged. These include inflammation, wound healing, angiogenesis, and bone metabolism. Finally, recent evidence supports the hypothesis that the nonhemostatic functions of VWF directly contribute to pathogenic mechanisms in a variety of diverse diseases including sepsis, malaria, sickle cell disease, and liver disease. In this manuscript, we review the accumulating data regarding novel ligand interactions for VWF and critically assess how these interactions may affect cellular biology. In addition, we consider the evidence that nonhemostatic VWF functions may contribute to the pathogenesis of human diseases beyond thrombosis and bleeding.

ABO and Rhesus blood groups and multiple health outcomes: an umbrella review of systematic reviews with meta-analyses of observational studies

BACKGROUND

Numerous studies have been conducted to investigate the relationship between ABO and Rhesus (Rh) blood groups and various health outcomes. However, a comprehensive evaluation of the robustness of these associations is still lacking.

METHODS

We searched PubMed, Web of Science, Embase, Scopus, Cochrane, and several regional databases from their inception until Feb 16, 2024, with the aim of identifying systematic reviews with meta-analyses of observational studies exploring associations between ABO and Rh blood groups and diverse health outcomes. For each association, we calculated the summary effect sizes, corresponding 95% confidence intervals, 95% prediction interval, heterogeneity, small-study effect, and evaluation of excess significance bias. The evidence was evaluated on a grading scale that ranged from convincing (Class I) to weak (Class IV). We assessed the certainty of evidence according to the Grading of Recommendations Assessment, Development, and Evaluation criteria (GRADE). We also evaluated the methodological quality of included studies using the A Measurement Tool to Assess Systematic Reviews (AMSTAR). AMSTAR contains 11 items, which were scored as high (8-11), moderate (4-7), and low (0-3) quality. We have gotten the registration for protocol on the PROSPERO database (CRD42023409547).

RESULTS

The current umbrella review included 51 systematic reviews with meta-analysis articles with 270 associations. We re-calculated each association and found only one convincing evidence (Class I) for an association between blood group B and type 2 diabetes mellitus risk compared with the non-B blood group. It had a summary odds ratio of 1.28 (95% confidence interval: 1.17, 1.40), was supported by 6870 cases with small heterogeneity (I2 = 13%) and 95% prediction intervals excluding the null value, and without hints of small-study effects (P for Egger's test > 0.10, but the largest study effect was not more conservative than the summary effect size) or excess of significance (P < 0.10, but the value of observed less than expected). And the article was demonstrated with high methodological quality using AMSTAR (score = 9). According to AMSTAR, 18, 32, and 11 studies were categorized as high, moderate, and low quality, respectively. Nine statistically significant associations reached moderate quality based on GRADE.

CONCLUSIONS

Our findings suggest a potential relationship between ABO and Rh blood groups and adverse health outcomes. Particularly the association between blood group B and type 2 diabetes mellitus risk.

Hematological Abnormalities Among Malaria Infected Adult Patients in Association with ABO Blood Groups at Jinella Health Center, Harar, Eastern Ethiopia

Background

Hematological abnormalities are a common complication of malaria infection. However, there is a paucity of evidence regarding it among malaria-infected adult patients in association with the ABO blood group in Ethiopia, particularly in the Harari Region. Therefore, this study aimed to assess the hematological abnormalities among malaria-infected adult patients in association with ABO blood groups at Jinella Health Center, Harar, Eastern Ethiopia.

Methods

An institutional-based cross-sectional study was conducted from July 10, 2022, to January 10, 2023. Four milliliters of venous blood were collected from each study participant. Drops of blood were used for blood film preparation. ABO blood group was determined by agglutination test using monoclonal anti-sera (Agape Diagnostics Ltd., India). A complete blood count was done using the DxH 800 (Beckman Coulter, Inc, Miami, FL) hematology analyzer. The data were analyzed using SPSS version 26. Bivariable and multivariable logistic regression models were fitted. The level of significance was declared at a p-value of <0.05.

Results

The study revealed that 47.2% (95% CI: 41.0 53.6) of the participants were anemic. Being female (AOR = 3.18, 95% CI = 1.67, 6.04), having the A blood group (AOR = 2.75, CI = 1.20, 6.31), and being infected with P. falciparum (AOR = 2.64, CI = 1.26, 5.53) were all significantly associated with malaria anemia. The overall prevalence of thrombocytopenia was also 67.7% (95% CI: 61.7-73.4%). It was significantly associated with P. falciparum infection (AOR = 8.03, CI = 3.53, 18.25) and high parasitemia levels (AOR = 4.40, CI = 1.57, 12.32).

Conclusion

Patients with malaria who belonged to the "A" blood group in the study area had anemia as a serious health problem. Hence, frequently checking for anemia in patients with malaria who have blood group "A" can help with early detection and better management of anemia.

ABO blood group and risk of malaria during pregnancy: a systematic review and meta-analysis

The association between the ABO blood group and the risk of malaria during pregnancy has not been clearly established. The present study summarised relevant knowledge and reassessed the association through meta-analysis. Articles in MEDICINE and PubMed published before 30 November 2021 were searched. Five studies satisfied the inclusion criteria and were enrolled in the meta-analysis. It was shown that primiparae with different ABO blood group, multiparae with blood group A and non-A, AB and non-AB had a comparable risk of malaria. However, multiparae with blood group B had a significantly higher risk than non-B group [odds ratio (OR) = 1.23, 95% confidence interval (CI) was 1.01 to 1.50, P = 0.04], while multiparae with blood group O had a significantly lower risk than non-O group (OR = 0.78, 95% CI was 0.63 to 0.97, P = 0.03). Therefore, the ABO blood group may not result in a different risk of malaria in primiparae. Blood group B is potentially a risk factor while blood group O is a protective factor for multiparae.

The Cytokines Responses against Parvovirus B19 in Miscarriage Women and the Susceptibility of their RhD Blood Type to Contract Parvovirus B19 in South of Iraq

Background

Parvovirus B19 (B19) infection is linked with various diseases. Cytokines play critical roles in cellular response to viral infection. It has also been reported that's susceptibility of the ABO blood type people to several viral infection. In this study, we evaluated interleukin 6 (IL-6), interleukin 8(IL-8), and interferon gamma (IFN-γ) levels in aborted women infected with parvovirus B19 (B19+/Abr+) and uninfected with B19(B19-/Abr+) in comparison with healthy women (B12-/Abr-) and susceptibility of their RhD blood type to contract B19.

Methods

B19+/Abr+ were diagnosed using IgM and IgG antibodies against B19, and the concentrations of IL-6, IL-8, and IFN-γ were determined using enzyme-linked immunosorbent assay (ELISA) test in both B19+/Abr+, B19-/Abr+, and B19-/Abr-. Here, we also collected blood groups, number of abortion, and gestational ages from 200 B19+/Abr+ along with the same number ofB19-/Abr+ and B19-/Abr-.

Results

The levels of IFN-γ were higher in serum of B19-/Abr+andB19+/Abr+ group in comparison to B19-/Abr-, while the serum levels of IL-6, IL-8were increased in B19+/Abr+ group in comparisontoB19-/Abr+ and B19-/Abr-. Our analyzed data also showed that aborted women with RhD+ are more susceptible to contract s B19 than people with RhD- blood type.

Conclusion

B19 infection may differently modulate the amount of cytokines in the plasma of aborted women. So, it can be suggested that IL-6, IL-8, and IFN-γ potentially useful as markers for inflammation intrauterine. The susceptibility/protection of aborted women against B19 might be determined based on RhD blood type.

Type O blood, the MCHC, and the reticulocyte count impact the early recurrence of primary warm-antibody autoimmune hemolytic anemia in children: A retrospective cohort analysis

OBJECTIVE

Primary warm-antibody autoimmune hemolytic anemia (w-AIHA) is prone to recurrence in children. In this study, we aimed to identify risk indicators for the early recurrence of primary w-AIHA and construct an effective recurrence risk assessment model.

METHODS

This was a retrospective cohort study. The clinical data of patients hospitalized with primary w-AIHA in the Department of Hematology and Oncology, Children's Hospital of Chongqing Medical University, between 1 January 2018 and 30 September 2021, were collected at the initial diagnosis. Univariate and multivariate logistic regression analyses were used to determine risk indicators for the early recurrence of primary w-AIHA in children, and ROC curve and Kaplan-Meier survival analyses were used for verification. Finally, a risk assessment model for early recurrence in children with primary w-AIHA was constructed using Cox regression and visualized using a nomogram. The model was also verified internally and externally.

RESULTS

This study included 62 children with primary w-AIHA. Of which, 18 experienced recurrence 1 year after the initial diagnosis. The univariate and multivariate logistic regression analyses showed that type O blood and the reticulocyte count (Ret) were risk indicators for the early recurrence of pediatric primary w-AIHA (P = 0.009, 0.047, respectively). The mean corpuscular hemoglobin concentration (MCHC) is a protective factor (P = 0.040). According to the ROC curve and Kaplan-Meier survival analyses, children with primary w-AIHA whose blood type was O or had an MCHC of <313.5 pg/fL or a Ret of ≥0.161×10¹²/L had a higher risk of early recurrence (HR = 2.640, 4.430 and 4.450, respectively, and P = 0.040, 0.015 and 0.018, respectively). The blood types (O), MCHCs, and Rets of 56 patients were incorporated into the Cox regression model, and the recurrence risk assessment model for children with primary w-AIHA was successfully constructed and visualized using a nomogram. The calibration curves and decision-curve analysis (DCA) suggested that the risk model has clinical applicability and effectiveness.

CONCLUSION

Children with type O blood and an MCHC value of <313.5 pg/fL or a Ret value of ≥0.161×10¹²/L have a higher risk of early recurrence. The risk assessment model for the early recurrence of pediatric primary w-AIHA constructed in this study has good clinical applicability and effectiveness.

The von Willebrand factor - ADAMTS-13 axis in malaria

Cerebral malaria (CM) continues to be associated with major morbidity and mortality, particularly in children aged <5 years in sub-Saharan Africa. Although the biological mechanisms underpinning severe malaria pathophysiology remain incompletely understood, studies have shown that cytoadhesion of malaria-infected erythrocytes to endothelial cells (ECs) within the cerebral microvasculature represents a key step in this process. Furthermore, these studies have also highlighted that marked EC activation, with secretion of Weibel-Palade bodies (WPBs), occurs at a remarkably early stage following malaria infection. As a result, plasma levels of proteins normally stored within WPBs (including high-molecular-weight von Willebrand factor [VWF] multimers, VWF propeptide, and angiopoietin-2) are significantly elevated. In this review, we provide an overview of recent studies that have identified novel roles through which these secreted WPB glycoproteins may directly facilitate malaria pathogenesis through a number of different platelet-dependent and platelet-independent pathways. Collectively, these emerging insights suggest that hemostatic dysfunction, and in particular disruption of the normal VWF-ADAMTS-13 axis, may be of specific importance in triggering cerebral microangiopathy. Defining the molecular mechanisms involved may offer the opportunity to develop novel targeted therapeutic approaches, which are urgently needed as the mortality rate associated with CM remains in the order of 20%.

High susceptibility to severe malaria among patients with A blood group versus those with O blood group: A cross-sectional study in the Democratic Republic of the Congo

This study aimed to assess the association of severe malaria infection with the ABO blood groups among acute febrile patients at the General Hospital of Rungu, in the Democratic Republic of the Congo. This cross-sectional study was conducted between August and October 2018. Plasmodium falciparum-infected individuals were categorized as severe malaria and uncomplicated malaria. A total of 400 febrile patients were enrolled. The majority (n = 251; 62.8%) was positive P. falciparum in microscopy test, of whom 180 (71.7%) had uncomplicated malaria and 71 (28.3%) severe malaria; 32.3%, 18.3%, 2.8%, and 46.6% were found to be blood group of A, B, AB, and O, respectively. In the multivariate analysis using the logistic regression models, severe malaria was high among patients with A blood group compared to those with O blood group (45.8% vs. 13.7%; adjusted odds ratio: 5.3 [95% confidence interval: 2.7–10.5]; P < 0.001). This survey demonstrates that patients with A blood group had a high susceptibility to severe malaria compared to those with O blood group.

Impact of ABO and Rhesus blood groups on COVID-19 susceptibility and severity: A case-control study

Early evidence from China suggested that blood groups may be involved in susceptibility to COVID‐19. Several subsequent studies reported controversial results. We conducted a retrospective matched case‐control study that aims to investigate the association between blood groups and the risk and/or severity of COVID‐19. We compared the blood groups distribution of 474 patients admitted to the hospital for COVID‐19 between March 2020 and March 2021, to that of a positive control group of outpatients infected with COVID‐19 and matched them for sex and age, as well as to the distribution in the general population. Three hundred and eighteen HC+ pairs with available blood group information were matched. The proportion of group A Rh+ in hospitalized patients (HC+) was 39.9% (CI 35.2%–44.7%), compared to 44.8% (CI 39.8%–49.9%) and 32.3% in the positive outpatient controls (C+) and the general population (C−), respectively. Both COVID‐19‐positive groups (HC+ and C+) had significantly higher proportions of group A Rh+ compared to the general population (p = 0.0019 and p < 0.001, respectively), indicating that group A Rh+ increases susceptibility to COVID‐19. Although blood group A Rh+ was more frequent in the outpatients C+ compared to the hospitalized group HC+, the association did not reach statistical significance, indicating that blood group A Rh+ is not associated with severity. There was no significant relationship between COVID‐19 and other blood groups. Our findings indicate that blood group A Rh+ increases the susceptibility for COVID‐19 but is not associated with higher disease severity.

Abo Blood Group, Atherothrombotic Comorbidities, and COVID-19: A Case-Control Study of their Association in the Mexican Population

Background

COVID-19 has been associated with negative results in patients with A blood group and with a better evolution in O blood group individuals.

Aim

Because the evidence regarding ABO blood groups and COVID was empirically not that clear in our country, we tested the association regarding COVID-19 and blood groups.

Material and Methods

Adult patients were enrolled in this prospective, case-control, observational multicenter study. Patients with a confirmed diagnosis of COVID-19 were assigned to one of three groups based on the clinical presentation of the infection. Age, gender, ABO and Rh blood groups, body mass index, history of diabetes mellitus or high blood pressure, and smoking were recorded directly or from their clinical charts. ABO blood group was obtained from 5,000 blood donors (50% each gender). Atherothrombotic variables were compared with a nation-wide data collection.

Results

A total of 2,416 patients with COVID-19 were included (women:39.6%; men:60.4%). There were no significant differences between cases and controls in terms of age. O blood group was the most frequently found in healthy donors and COVID-19 patients, but this blood group was significantly higher in COVID-19 patients vs. healthy donors. ABO blood group was not associated with the final health status in COVID-19 patients. Obesity, diabetes mellitus, hypertension and smoking were significantly more frequent among COVID-19 patients.

Conclusion

The proposed protective effect of the O blood group in COVID-19 patients could not be reproduced in the Mexican population while some atherothrombotic risk factors had a significant effect on the clinical evolution.

ABO blood group and COVID-19: an updated systematic literature review and meta-analysis

BACKGROUND

Following the first reports in the literature, the association between the ABO blood group and SARS-CoV-2 infection has been investigated by a number of studies, although with varying results. The main object of this systematic review was to assess the relationship between the ABO blood group and the occurrence and severity of COVID-19.

MATERIALS AND METHODS

A systematic literature search using appropriate MeSH terms was performed through Medline and PubMed. The outcomes considered were the prevalence of the blood group O vs non-O types in SARS-CoV-2 infected and non-infected subjects, and the severity of SARS-CoV-2 infection according to ABO group. The methodological quality of the studies included in the analysis was assessed with the Newcastle-Ottawa Scale, and the overall quality of the available evidence using the GRADE system. Benchmarks used to evaluate the effect size were odd ratios (ORs) for case control studies and risk ratios (RRs) for cohort studies.

RESULTS

Twenty-one studies were included in the analysis. Overall, individuals with group O had a lower infection rate compared to individuals of non-O group (OR: 0.81; 95% CI: 0.75, 0.86). However, the difference in the effect size was significantly lower in cohort studies compared to case control studies. No evidence was found indicating an effect of the O type on the disease severity in the infected patients.

DISCUSSION

We have found low/very low evidence that group O individuals are less susceptible to SARS-CoV-2 infection compared to those in the non-O group. No evidence was found indicating an effect of the O type on disease severity in SARS-CoV-2 infection.

The relationship between ABO blood group, von Willebrand factor, and primary hemostasis

Numerous studies have reported significant associations between ABO blood group and risk of cardiovascular disease. These studies have consistently demonstrated that thrombotic risk is significantly reduced in individuals in blood group O. Nevertheless, the biological mechanisms through which ABO influences hemostasis have remained poorly understood. Exciting recent data have provided novel insights into how these ABO effects are modulated and have highlighted that ABO group significantly influences platelet plug formation at sites of vascular injury (primary hemostasis). In particular, ABO affects multiple aspects of von Willebrand factor (VWF) biology. In keeping with their reduced thrombotic risk, plasma VWF levels are ∼25% lower in healthy group O compared with healthy group non-O individuals. In addition, blood group O VWF demonstrates enhanced susceptibility to ADAMTS13 proteolysis. Finally, preliminary findings suggest that the interaction of group O VWF with platelets may also be reduced. Although the molecular mechanisms underlying these ABO effects on VWF have not been fully elucidated, it seems likely that they are mediated in large part by the ABO(H) carbohydrate structures that are carried on both the N- and O-linked glycans of VWF. Interestingly, ABO(H) determinants are also expressed on several different platelet surface glycoprotein receptors. Recent studies support the hypothesis that ABO group not only exerts major quantitative and qualitative effects on VWF, but also affect specific aspects of platelet function. Given the severe morbidity and the mortality associated with thrombotic disorders, defining the mechanisms underlying these ABO effects is not only of scientific interest, but also of direct clinical importance.

ABO blood type association with SARS-CoV-2 infection mortality: A single-center population in New York City

Background

Severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) has a variable clinical course with significant mortality. Early reports suggested higher rates of SARS‐CoV‐2 infection in patients with type A blood and enrichment of type A individuals among COVID‐19 mortalities.

Study Design and Methods

The study includes all patients hospitalized or with an emergency department (ED) visit who were tested for SARS‐CoV‐2 between March 10, 2020 and June 8, 2020 and had a positive test result by nucleic acid test (NAT) performed on a nasopharyngeal swab specimen. A total of 4968 patients met the study inclusion criteria, with a subsequent 23.1% (n = 1146/4968) all‐cause mortality rate in the study cohort. To estimate overall risk by ABO type and account for the competing risks of in‐hospital mortality and discharge, we calculated the cumulative incidence function (CIF) for each event. Cause‐specific hazard ratios (csHRs) for in‐hospital mortality and discharge were analyzed using multivariable Cox proportional hazards models.

Results

Type A blood was associated with the increased cause‐specific hazard of death among COVID‐19 patients compared to type O (HR = 1.17, 1.02–1.33, p = .02) and type B (HR = 1.32,1.10–1.58, p = .003).

Conclusions

Our study shows that ABO histo‐blood group type is associated with the risk of in‐hospital death in COVID‐19 patients, warranting additional inquiry. Elucidating the mechanism behind this association may reveal insights into the susceptibility and/or immunity to SARS‐CoV‐2.

Toward Personalized Treatment for Patients with Low von Willebrand Factor and Quantitative von Willebrand Disease

The biological mechanisms involved in the pathogenesis of type 2 and type 3 von Willebrand disease (VWD) have been studied extensively. In contrast, although accounting for the majority of VWD cases, the pathobiology underlying partial quantitative VWD has remained somewhat elusive. However, important insights have been attained following several recent cohort studies that have investigated mechanisms in patients with type 1 VWD and low von Willebrand factor (VWF), respectively. These studies have demonstrated that reduced plasma VWF levels may result from either (1) decreased VWF biosynthesis and/or secretion in endothelial cells and (2) pathological increased VWF clearance. In addition, it has become clear that some patients with only mild to moderate reductions in plasma VWF levels in the 30 to 50 IU/dL range may have significant bleeding phenotypes. Importantly in these low VWF patients, bleeding risk fails to correlate with plasma VWF levels and inheritance is typically independent of the VWF gene. Although plasma VWF levels may increase to > 50 IU/dL with progressive aging or pregnancy in these subjects, emerging data suggest that this apparent normalization in VWF levels does not necessarily equate to a complete correction in bleeding phenotype in patients with partial quantitative VWD. In this review, these recent advances in our understanding of quantitative VWD pathogenesis are discussed. Furthermore, the translational implications of these emerging findings are considered, particularly with respect to designing personalized treatment plans for VWD patients undergoing elective procedures.

Human ABO Blood Groups and Their Associations with Different Diseases

INTRODUCTION

Human ABO blood type antigens exhibit alternative phenotypes and genetically derived glycoconjugate structures that are located on the red cell surface which play an active role in the cells' physiology and pathology. Associations between the blood type and disease have been studied since the early 1900s when researchers determined that antibodies and antigens are inherited. However, due to lack of antigens of some blood groups, there have been some contentious issues with the association between the ABO blood group and vulnerability to certain infectious and noninfectious diseases.

OBJECTIVE

To review different literatures that show the association between ABO blood groups and different diseases.

METHOD

Original, adequate, and recent articles on the same field were researched, and the researcher conducted a comprehensive review on this topic. Thus, taking out critical discussions, not only a descriptive summary of the topic but also contradictory ideas were fully retrieved and presented in a clear impression. In addition, some relevant scientific papers published in previous years were included. The article search was performed by matching the terms blood types/groups with a group of terms related to different diseases. The articles were screened and selected based on the title and abstract presented.

RESULTS

The susceptibility to various diseases, such as cancer, cardiovascular diseases, infections and hematologic disorders, cognitive disorders, circulatory diseases, metabolic diseases, and malaria, has been linked with ABO blood groups. Moreover, blood group AB individuals were found to be susceptible to an increased risk of cognitive impairment which was independent of geographic region, age, race, and gender. Disorders such as hypertension, obesity, dyslipidemia, cardiovascular disease (CVD), and diabetes were also more prevalent in individuals with cognitive impairment. Early etiological studies indicated that blood type O has a connection with increased incidence of cholera, plague, tuberculosis infections, and mumps, whereas blood type A is linked with increased incidence of smallpox and Pseudomonas aeruginosa infection; blood type B is also associated with increased incidence of gonorrhea, tuberculosis, and Streptococcus pneumoniae, E. coli, and salmonella infections; and blood type AB is associated with increased incidence of smallpox and E. coli and salmonella infections. Diabetes mellitus, hypercholesterolemia, arterial hypertension, and family history for ischemic heart disease are the most common risk factors for cardiovascular diseases and can be genetically transmitted to offspring. Higher incidence of cancers in the stomach, ovaries, salivary glands, cervix, uterus, and colon/rectum was common in blood type A people than in O type people. The link between the ABO blood type and thromboembolic diseases and bleeding risk are intervened by the glycosyltransferase activity and plasma levels and biologic activity of vWF (Von Willebrand factor), a carrier protein for coagulation factor VIII which is low in O type.

CONCLUSION

Several studies related to the ABO phenotype show that genetically determined human ABO blood groups were correspondingly linked with an increased risk of various infectious and noninfectious diseases. However, further investigations are needed particularly on the molecular level of ABO blood groups and their association with various diseases.

RhD blood type significantly influences susceptibility to contract COVID-19 among a study population in Iraq

The ABO blood type has been reported to be associated with several diseases such as hepatitis and malaria. Recently, some studies have reported that people with O blood type are protected against COVID-19, while people with A blood type are more susceptible to contract this disease. Here, we analysed data from 5668 COVID-19 patients along with the same number of control samples in a study population in Iraq. Our analysis confirms that people with O blood type are protected partially against COVID-19. Notably, we demonstrate that people with RhD- are more susceptible to contract COVID-19 than people with RhD+ blood type. The blood types are associated with some clinical symptoms such as headache and asthenia of COVID-19, but there is no association with other symptoms. There is no association between blood types and deaths among COVID-19 patients. This study suggests that in addition to ABO, RhD blood type influences the susceptibility to contract COVID-19. Overall, we conclude that susceptibility/protection against COVID-19 may not be determined based only on blood types among the global population as this might vary based on a number of other factors such as ethnicity, geographical locations, occupation and the level of exposure to infected people.

Associations between blood type and COVID-19 infection, intubation, and death

The rapid global spread of the novel coronavirus SARS-CoV-2 has strained healthcare and testing resources, making the identification and prioritization of individuals most at-risk a critical challenge. Recent evidence suggests blood type may affect risk of severe COVID-19. Here, we use observational healthcare data on 14,112 individuals tested for SARS-CoV-2 with known blood type in the New York Presbyterian (NYP) hospital system to assess the association between ABO and Rh blood types and infection, intubation, and death. We find slightly increased infection prevalence among non-O types. Risk of intubation was decreased among A and increased among AB and B types, compared with type O, while risk of death was increased for type AB and decreased for types A and B. We estimate Rh-negative blood type to have a protective effect for all three outcomes. Our results add to the growing body of evidence suggesting blood type may play a role in COVID-19.

Expresser phenotype determines ABO(H) blood group antigen loading on platelets and von Willebrand factor

ABO blood group is associated with cardiovascular disease, with significantly lower risk in blood group O individuals. ABO(H) blood group determinants are expressed on different glycoproteins on platelet surfaces. In addition, ABO(H) structures are also present on VWF glycans. These ABO(H) carbohydrates influence both platelet and VWF function. Previous studies have reported that approximately 5-10% of normal blood donors express abnormally high or low levels of A or B blood group antigens on their platelet surfaces (high expresser phenotype, HXP or low expresser phenotype, LXP respectively). In this study, the biological effects of the ABO Expresser phenotype were investigated. ABO(H) expression on platelets and plasma VWF was studied in a series of 541 healthy blood donors. Overall, 5.6% of our study cohort were classified as HXP, whilst 4.4% satisfied criteria for LXP. We demonstrate that genotype at the ABO blood group locus plays a critical role in modulating the platelet HXP phenotype. In particular, A1A1 genotype is a major determinant of ABO high-expresser trait. Our data further show that ABH loading on VWF is also affected by ABO expresser phenotype. Consequently, A antigen expression on VWF was significantly elevated in HXP individuals and moderately reduced in LXP subjects (P < 0.05). Collectively, these findings suggest that ABO expresser phenotype influences primary hemostasis though several different pathways. Further studies will be required to define whether inter-individual variations in ABO(H) expression on platelets and/or VWF (particularly HXP and LXP) impact upon risk for cardiovascular disease.

Testing the association between blood type and COVID-19 infection, intubation, and death

The rapid global spread of the novel coronavirus SARS-CoV-2 has strained healthcare and testing resources, making the identification and prioritization of individuals most at-risk a critical challenge. Recent evidence suggests blood type may affect risk of severe COVID-19. We used observational healthcare data on 14,112 individuals tested for SARS-CoV-2 with known blood type in the New York Presbyterian (NYP) hospital system to assess the association between ABO and Rh blood types and infection, intubation, and death. We found slightly increased infection prevalence among non-O types. Risk of intubation was decreased among A and increased among AB and B types, compared with type O, while risk of death was increased for type AB and decreased for types A and B. We estimated Rh-negative blood type to have a protective effect for all three outcomes. Our results add to the growing body of evidence suggesting blood type may play a role in COVID-19.

Blood type and outcomes in patients with COVID-19

This study aimed to determine if there is an association between ABO blood type and severity of COVID-19 defined by intubation or death as well as ascertain if there is variability in testing positive for COVID-19 between blood types. In a multi-institutional study, all adult patients who tested positive for COVID-19 across five hospitals were identified and included from March 6th to April 16th, 2020. Hospitalization, intubation, and death were evaluated for association with blood type. Univariate analysis was conducted using standard techniques and logistic regression was used to determine the independent effect of blood type on intubation and/or death and positive testing. During the study period, there were 7648 patients who received COVID-19 testing throughout the institutions. Of these, 1289 tested positive with a known blood type. A total of 484 (37.5%) were admitted to hospital, 123 (9.5%) were admitted to the ICU, 108 (8.4%) were intubated, 3 (0.2%) required ECMO, and 89 (6.9%) died. Of the 1289 patients who tested positive, 440 (34.2%) were blood type A, 201 (15.6%) were blood type B, 61 (4.7%) were blood type AB, and 587 (45.5%) were blood type O. On univariate analysis, there was no association between blood type and any of the peak inflammatory markers (peak WBC, p = 0.25; peak LDH, p = 0.40; peak ESR, p = 0.16; peak CRP, p = 0.14) nor between blood type and any of the clinical outcomes of severity (admission p = 0.20, ICU admission p = 0.94, intubation p = 0.93, proning while intubated p = 0.58, ECMO p = 0.09, and death p = 0.49). After multivariable analysis, blood type was not independently associated with risk of intubation or death (referent blood type A; blood type B: AOR: 0.72, 95% CI: 0.42-1.26, blood type AB: AOR: 0.78, CI: 0.33-1.87, blood type O: AOR: 0.77, CI: 0.51-1.16), rhesus factor positive (Rh+): AOR: 1.03, CI: 0.93-1.86. Blood type A had no correlation with positive testing (AOR: 1.00, CI: 0.88-1.13), blood type B was associated with higher odds of testing positive for disease (AOR: 1.28, CI: 1.08-1.52), AB was also associated with higher odds of testing positive (AOR: 1.37, CI: 1.02-1.83), and O was associated with a lower risk of testing positive (AOR: 0.84, CI: 0.75-0.95). Rh+ status was associated with higher odds of testing positive (AOR: 1.23, CI: 1.003-1.50). Blood type was not associated with risk of intubation or death in patients with COVID-19. Patients with blood types B and AB who received a test were more likely to test positive and blood type O was less likely to test positive. Rh+ patients were more likely to test positive.

ABO blood group should be considered and reported when red blood cell exchange transfusion is used to treat Plasmodiumfalciparum Malaria patients

Laboratory and epidemiologic studies have clarified how persons born with malaria-resistant red blood cells (RBCs)-like group-O, sickle-trait, and C-trait RBCs-are protected against death or severe disease due to Plasmodiumfalciparum (Pf) infection. Compared to malaria-promoting RBCs-like non-O or hemoglobin-AA RBCs-inborn RBC protection against severe Pf malaria can be profound: up to 10-fold greater. Given that "the Berlin patient" success showed patients do not have to be born with disease-resistant cells to benefit from them, why have the biologically plausible benefits of exchange transfusion (ET) of malaria-resistant RBCs not yet been evaluated? Unfortunately, a 2013 ET-for-malaria meta-analysis could not quantify the impact on mortality of ET of malaria-resistant RBCs because RBC malaria resistance variables (ABO group, hemoglobin type, enzyme levels, etc.) had not been reported in any of the ET studies used in that meta-analysis. To promote evaluation of the therapeutic impact of specific malaria-resistant RBCs, we urge clinicians to always report ABO blood group (and all other RBC malaria-resistance variables they are aware of) when they use ET to rescue Pf-infected patients. Prudent selection of donor RBCs has successfully optimized ET for sickle cell disease patients, and this precedent suggests selection of special malaria-resistant donor RBCs may optimize ET for Pf-malaria patients. Given that ET is used worldwide as a rescue adjunct, we feel it is most prudent to now assume-until proven otherwise-that considering and reporting the Pf-malaria-resistance variables of the RBCs to be transfused-at least ABO status-will help optimize ET-for-malaria.

Effect of ABO blood group on asymptomatic, uncomplicated and placental Plasmodium falciparum infection: systematic review and meta-analysis

BACKGROUND

Malaria clinical outcomes vary by erythrocyte characteristics, including ABO blood group, but the effect of ABO blood group on asymptomatic, uncomplicated and placental Plasmodium falciparum (P. falciparum) infection remains unclear. We explored effects of ABO blood group on asymptomatic, uncomplicated and placental falciparum infection in the published literature.

METHODS

A systematic review and meta-analysis was performed using the preferred reporting items for systematic reviews and meta-analyses guidelines. Articles in Pubmed, Embase, Web of Science, CINAHL and Cochrane Library published before February 04, 2017 were searched without restriction. Studies were included if they reported P. falciparum infection incidence or prevalence, stratified by ABO blood group.

RESULTS

Of 1923 articles obtained from the five databases (Embase = 728, PubMed = 620, Web of Science = 549, CINAHL = 14, Cochrane Library = 12), 42 met criteria for systematic review and 37 for meta-analysis. Most studies (n = 30) were cross-sectional, seven were prospective cohort, and five were case-control studies. Meta-analysis showed similar odds of uncomplicated P. falciparum infection among individuals with blood group A (summary odds ratio [OR] 0.96, 15 studies), B (OR 0.89, 15 studies), AB (OR 0.85, 10 studies) and non-O (OR 0.95, 17 studies) as compared to those with blood group O. Meta-analysis of four cohort studies also showed similar risk of uncomplicated P. falciparum infection among individuals with blood group non-O and those with blood group O (summary relative risk [RR] 1.03). Meta-analysis of six studies showed similar odds of asymptomatic P. falciparum infection among individuals with blood group A (OR 1.05), B (OR 1.03), AB (OR 1.23), and non-O (OR 1.07) when compared to those with blood group O. However, odds of active placental P. falciparum infection was significantly lower in primiparous women with non-O blood groups (OR 0.46, 95% confidence interval [CI] 0.23 - 0.69, I2 0.0%, three studies), particularly in those with blood group A (OR 0.41, 95% CI 0.003 - 0.82, I2 1.4%, four studies) than those with blood group O.

CONCLUSIONS

This study suggests that ABO blood group may not affect susceptibility to asymptomatic and/or uncomplicated P. falciparum infection. However, blood group O primiparous women appear to be more susceptible to active placental P. falciparum infection.

Effect of the ABO blood group on susceptibility to severe malaria: A systematic review and meta-analysis

Understanding how ABO blood group interacts with Plasmodium falciparum (P. falciparum) infection may facilitate development of antimalarial treatments and vaccines. This study systematically summarizes information on the relationship of ABO blood group with severe P. falciparum infection, level of parasitemia and haemoglobin. A total of 1923 articles were retrieved from five databases. After removal of duplicates, and two levels of screening, 21 articles were selected for inclusion in the meta-analysis. A meta-analysis of the studies showed an increased odds of severe P. falciparum infection among individuals with blood group A, B, AB or non-O compared with blood group O. However, the difference in the level of P. falciparum parasitemia was not significant among individuals with blood group A or non-O compared with blood group O. The difference in haemoglobin level among P. falciparum infected individuals was also not significant between those with blood group A, B or AB versus those with blood group O.

Heterogeneity of O blood group in India: Peeping through the window of molecular biology

BACKGROUND:

Molecular genotyping of ABO blood group system has identified more than 60 “O” group alleles based on the single-nucleotide polymorphisms present in the ABO gene. Heterogeneity of O group alleles has been observed in various countries from South America, Europe, Middle East, and Asia. India is a vast country with more than 1300 million population which is divided into various ethnic and tribal groups. However, very little is known about the heterogeneity of O alleles in Indians.

MATERIALS AND METHODS:

A total of 116 O group individuals from the mixed population of Mumbai, India, were enrolled in the present study. DNA was extracted using the standard phenol–chloroform method. The exons 6 and 7 of the ABO gene were genotyped by polymerase chain reaction-single-strand conformation polymorphism and/or DNA sequencing. The genotyping results were compared with our earlier findings.

RESULTS AND DISCUSSION:

Overall, ten different genotypes were identified. Three rare alleles, namely, O05, O11, and O26 were seen in the mixed group category. These results suggest that there is an internal heterogeneity in the mixed group while Dhodias and Parsis, the groups which were screened earlier, seem to be more homogenous groups. An important piece of information emerges out from this study, that is, O01O02 genotype is expressing some selective force in population groups screened in India as well as many other groups worldwide.

CONCLUSION:

In the future, molecular genotyping of the ABO blood group system among different ethnic and tribal Indian groups would help in generating data to fill up the gaps in the molecular ABO map of the world.

Beta-globin gene haplotypes and selected Malaria-associated variants among black Southern African populations

Partial carrier-resistance to Plasmodium falciparum malaria conferred by the sickle cell (HbS) mutation has resulted in the local amplification and positive selection of sickle cell disease (SCD) in malaria-endemic regions and particularly in sub-Saharan Africa (SSA). The present study investigated the β-globin gene haplotypes, and selected malaria-associated variants among three cohorts of Bantu-speaking individuals from Malawi, Zimbabwe and South Africa compared with reports with data from others SSA populations. The data suggest a south-ward frequency decrease of malaria-associated variants in SSA linked to the evolutionary dynamics of various African populations’ genomes through selective pressure of malaria. These selected genomics differences, positive selection of SCD in malaria-endemic regions among ‘Bantus’ from various part of Africa emphasise the evidence of the dissociation between genetics, anthropology and culture. The present study also showed a relatively prevalent Benin haplotype, which is mostly found in West Africa, among Southern African Blacks and very low Bantu haplotype, which could suggest a major migration route, of Southern Africa Bantu, along the African west coast, post-occurrence of the Sickle cell mutation, which date remain to be fully elucidated.

Relative Susceptibilities of ABO Blood Groups to Plasmodium falciparum Malaria in Ghana

The clinical outcome of falciparum malaria in endemic areas is influenced by erythrocyte polymorphisms including the ABO blood groups. Studies have reported association of ABO blood group to resistance, susceptibility, and severity of P. falciparum malaria infection. Individuals with blood group “A” have been found to be highly susceptible to falciparum malaria whereas blood group “O” is said to confer protection against complicated cases. We analyzed samples from 293 young children less than six years old with malaria in the Korle-Bu Teaching Hospital in Accra, Ghana. It was observed that group O was present in about 16.1% of complicated cases weighed against 40.9% of uncomplicated controls. Individuals with complicated malaria were about twice likely to be of blood groups A and B compared to group O (A versus O, OR = 1.90, 95% CI = 1.59–2.26, P < 0.0001; B versus O, OR = 1.82. 95% CI = 1.57–2.23, P < 0.0001). Blood group O participants with complicated diseases had low parasitaemia compared to the other blood groups (P < 0.0001). This may give blood group O individuals a survival advantage over the other groups in complicated malaria as suggested. Participants with complicated falciparum malaria were generally anaemic and younger than those with uncomplicated disease.

Emerging roles for hemostatic dysfunction in malaria pathogenesis

Severe Plasmodium falciparum malaria remains a leading cause of mortality, particularly in sub-Saharan Africa where it accounts for up to 1 million deaths per annum. In spite of the significant mortality and morbidity associated with cerebral malaria (CM), the molecular mechanisms involved in the pathophysiology of severe malaria remain surprisingly poorly understood. Previous studies have demonstrated that sequestration of P falciparum-infected erythrocytes within the microvasculature of the brain plays a key role in the development of CM. In addition, there is convincing evidence that both endothelial cell activation and platelets play critical roles in the modulating the pathogenesis of severe P falciparum malaria. In this review, we provide an overview of recent studies that have identified novel roles through which hemostatic dysfunction may directly influence malaria pathogenesis. In particular, we focus on emerging data suggesting that von Willebrand factor, coagulation cascade activation, and dysfunction of the protein C pathway may be of specific importance in this context. These collective insights underscore a growing appreciation of the important, but poorly understood, role of hemostatic dysfunction in malaria progression and, importantly, illuminate potential approaches for novel therapeutic strategies. Given that the mortality rate associated with CM remains on the order of 20% despite the availability of effective antimalarial therapy, development of adjunctive therapies that can attenuate CM progression clearly represents a major unmet need. These emerging data are thus not only of basic scientific interest, but also of direct clinical significance.

Association of ABO blood group and Plasmodium falciparum malaria in Dore Bafeno Area, Southern Ethiopia

OBJECTIVE

To assess the distribution of ABO blood group and their relationship with Plasmodium falciparum (P. falciparum) malaria among febrile outpatients who sought medical attention at Dore Bafeno Health Center, Southern Ethiopia.

METHODS

A total of 269 febrile outpatients who visited Dore Bafeno Health Center, Southern Ethiopia, were examined for malaria and also tested for ABO blood groups in January 2010. The blood specimens were collected by finger pricking, stained with Geimsa, and examined microscopically. Positive cases of the parasitemia were counted. CareStart™ Malaria Pf/Pv Combo was also used to test the blood specimens for malaria. ABO blood groups were determined by agglutination test using ERYCLONE(®) antisera. Data on socio-demographic characteristics and treatment status of the participants were also collected. Chi-square and ANOVA tests were used to assess the difference between frequencies and means, respectively.

RESULTS

Out of a total of 269 participants, 178 (66.2%) febrile patients were found to be infected with Plasmodium parasites, among which 146 (54.3%), 28 (10.4%), and 4 (1.5%) belonged to P. falciparum, P. vivax, and mixed infections, respectively. All febrile patients were also tested for ABO blood groups and 51.3%, 23.5%, 21.9% and 3.3% were found to be blood types of O, A, B and AB, respectively. Both total malaria infection and P. falciparum infection showed significant association with blood types (P<0.05). The proportion of A or B but not O phenotypes was higher (P<0.05) in individuals with P. falciparum as compared with non-infected individuals. The chance of having P. falciparum infection in patients with blood groups A, B and AB was 2.5, 2.5 and 3.3 times more than individuals showing blood O phenotypes, respectively. The mean P. falciparum malaria parasitaemia for blood groups A, B, AB, and O were 3 744/µL, 1 805/µL, 5 331/µL, and 1 515/µL, respectively (P<0.01).

CONCLUSIONS

The present findings indicate that individuals of blood groups A, B and AB are more susceptible to P. falciparum infection as compared with individuals of blood group O. Nevertheless, further in depth studies are required to clearly establish the role that ABO blood group plays in P. falciparum malaria.

Evolutionary aspects of ABO blood group in humans

The antigens of the ABO blood group system (A, B and H determinants) are complex carbohydrate molecules expressed on red blood cells and on a variety of other cell lines and tissues. Growing evidence is accumulating that ABO antigens, beyond their key role in transfusion medicine, may interplay with the pathogenesis of many human disorders, including infectious, cardiovascular and neoplastic diseases. In this narrative review, after succinct description of the current knowledge on the association between ABO blood groups and the most severe diseases, we aim to elucidate the particularly intriguing issue of the possible role of ABO system in successful aging. In particular, focus will be placed on studies evaluating the ABO phenotype in centenarians, the best human model of longevity.

Malaria Parasitaemia among Blood Donors in Ilorin, Nigeria

BACKGROUND

The prevalence of malaria parasitaemia among blood donors in Ilorin has not been documented. In this study, we determined the prevalence of malaria parasitaemia among blood donors in Ilorin, as well as, the sociodemographic and other factors associated with it.

METHOD

This was a hospital-based cross sectional study involving 308 consenting blood donors. The sociodemographic characteristics of participants as well as blood donation history were obtained using structured questionnaires specifically designed for this purpose. Giemsastained thick and thin blood films to identify malaria parasites were performed using standard method. ABO blood grouping and haemoglobin electrophoresis tests were also done using standard methods.

RESULTS

The prevalence of malaria parasitaemia among blood donors in Ilorin was 27.3%. The parasite species found were more of Plasmodium falciparum(85.7%) than Plasmodium malariae(14.3%) . There was no age or sex difference in malaria parasitaemia. (p-value of 0.8 and 0.32 respectively). A greater proportion of blood group O individuals had malaria parasitaemia than groups A and B but this difference was not significant (p-value = 0.13). There was also no significant difference among haemoglobin genotypes.

CONCLUSION

The prevalence of malaria parasites among blood donors in Ilorin is considerably high and lack of routine screening of blood puts recipients at risk. We recommend that routine screening for malaria parasites be commenced in our blood banks. Treatment of donor blood with riboflavin and UV light to inactivate malaria parasites and other infectious pathogens before they are transfused to patients may also be considered in our blood banks.

IFN-gamma and TNF associated with severe falciparum malaria infection in Saudi pregnant women

Background

Tumour necrosis factor (TNF) and interferon gamma (IFN-γ), encoded by TNF-836 C/A (rs 1800630) and IFN-γ -1616 C/T (rs2069705) genes, are key immunological mediators that are believed to both play protective and pathological roles in malaria. The aim of this study was to investigate the relationship between TNF-836 C/A and IFN-γ-1616 C/T polymorphism and susceptibility to severe malaria in pregnant women.

Methods

A prospective cohort (cross-sectional) study was conducted in pregnant women attending the out-patient clinic in King Fahad Specialist Hospital in Jazan (KFSHJ), with a clinical diagnosis of malaria. A total of one hundred and eighty six pregnant women were genotyped for single nucleotide polymorphism (SNP) for TNF and IFN-γ using Taqman® MGB Probes. Serum cytokine concentrations were measured by sandwich ELISA method.

Results

A hospital case–control study of severe malaria in a Saudi population identified strong associations with individual single-nucleotide polymorphisms in the TNF and IFN-γ genes, and defined TNF-836 C and IFN-γ-1616 T genotypes and alleles which were statistically significantly associated with severe malaria infection. Furthermore, TNF-836 CC and IFN-γ-1616 TT genotypes were associated with higher serum concentration of TNF and IFN-γ, respectively, and with susceptibility to severe malaria.

Conclusions

This data provides a starting point for functional and genetic analysis of the TNF and IFN-γ genomic region in malaria infection affecting Saudi populations.

Reduced prevalence of placental malaria in primiparae with blood group O

Background

Blood group O protects African children against severe malaria and has reached high prevalence in malarious regions. However, its role in malaria in pregnancy is ambiguous. In 839 delivering Ghanaian women, associations of ABO blood groups with Plasmodium falciparum infection were examined.

Methods

Plasmodium falciparum infection was diagnosed in placental blood samples by microscopy and PCR assays. Present or past infection was defined as the detection of parasitaemia or haemozoin by microscopy, or a positive PCR result. Blood groups were inferred from genotyping rs8176719 (indicating the O allele) and rs8176746/rs8176747 (distinguishing the B allele from the A allele).

Results

The majority of women had blood group O (55.4%); present or past P. falciparum infection was seen in 62.3% of all women. Among multiparae, the blood groups had no influence on P. falciparum infection. In contrast, primiparae with blood group O had significantly less present or past infection than women with non-O blood groups (61.5 vs 76.2%, P = 0.007). In multivariate analysis, the odds of present or past placental P. falciparum infection were reduced by 45% in blood group O primiparae (aOR, 0.55 [95% CI, 0.33–0.94]).

Conclusions

The present study shows a clear protective effect of blood group O against malaria in primiparae. This accords with findings in severe malaria and in vitro results. The data underline the relevance of host genetic protection among primiparae, i.e. the high-risk group for malaria in pregnancy, and contribute to the understanding of high O allele frequencies in Africa.

ABO blood groups influence macrophage-mediated phagocytosis of Plasmodium falciparum-infected erythrocytes

Erythrocyte polymorphisms associated with a survival advantage to Plasmodium falciparum infection have undergone positive selection. There is a predominance of blood group O in malaria-endemic regions, and several lines of evidence suggest that ABO blood groups may influence the outcome of P. falciparum infection. Based on the hypothesis that enhanced innate clearance of infected polymorphic erythrocytes is associated with protection from severe malaria, we investigated whether P. falciparum-infected O erythrocytes are more efficiently cleared by macrophages than infected A and B erythrocytes. We show that human macrophages in vitro and mouse monocytes in vivo phagocytose P. falciparum-infected O erythrocytes more avidly than infected A and B erythrocytes and that uptake is associated with increased hemichrome deposition and high molecular weight band 3 aggregates in infected O erythrocytes. Using infected A₁, A₂, and O erythrocytes, we demonstrate an inverse association of phagocytic capacity with the amount of A antigen on the surface of infected erythrocytes. Finally, we report that enzymatic conversion of B erythrocytes to type as O before infection significantly enhances their uptake by macrophages to observed level comparable to that with infected O wild-type erythrocytes. These data provide the first evidence that ABO blood group antigens influence macrophage clearance of P. falciparum-infected erythrocytes and suggest an additional mechanism by which blood group O may confer resistance to severe malaria.

Plasmodium falciparum malaria is considered to be one of the strongest forces for evolutionary selection pressure on the human genome. Different red blood cell variants associated with a survival advantage to P. falciparum infection have undergone positive selection. Blood group O is found more frequently in malaria-endemic regions and has been associated with protection against severe malaria and death. However the biological basis of protection remains unclear. In this study, we investigated innate immune clearance of P. falciparum-infected erythrocytes by macrophages as a possible mode of protection. We show that macrophages clear P. falciparum-infected O erythrocytes more avidly than infected A and B erythrocytes. We also report that enzymatic conversion of infected blood group B red cells to type as “O” like erythrocytes significantly enhances their uptake by macrophages to a level comparable to that observed with infected O wild type erythrocytes. These data provide the first evidence that clearance of P. falciparum-infected erythrocytes is influenced by human ABO blood groups and suggest a new mechanism by which blood group O may contribute to protection against severe malaria.

Association of ABO blood group and P. falciparum malaria related outcomes: a cross-sectional study in Ethiopia

Studies elucidate conflicting results about the relationships between ABO blood groups and Plasmodium infection outcomes in humans. This study examined association between ABO blood group and Plasmodium falciparum (P. falciparum) malaria related outcomes among 1065 malaria suspected febrile patients who attended Dore Baafano Health Center, southern Ethiopia, between December, 2010 and February, 2011. Blood specimens were collected and examined for malaria using Giemsa-staining, while stool specimens were examined for helminth infections using Kato-Katz method. Haemoglobin level and blood group were determined using hemocue machine and antisera hemagglutination test, respectively. Clinical data were also collected for the patients. Among the study participants, the proportion of O, A, B and AB blood groups were 40.1%, 30.1%, 29.0% and 14.3%, respectively, and P. falciparum malaria cases in the corresponding blood groups were 14.8%, 14.0%, 13.4% and 15.7%. The odds of non-severe P. falciparum malaria were not significantly different between individuals of blood group A versus O or B versus O or AB versus O. Mean haemoglobin concentration was significantly lower in P. falciparum infected blood type A individuals compared to P. falciparum infected blood type O (β=-1.25, 95% CI=-2.31 to -0.19) or non-A (β=-1.27, 95% CI=-2.23 to -0.32) individuals. The odds of P. falciparum malaria related anaemia was about three times higher in individuals with blood type A compared to those with blood type O (adjusted OR=2.82, 95% CI=1.05-7.56) or non-A individuals (adjusted OR=2.84, 95% CI=1.15-7.01). However, mean P. falciparum density did not significantly differ among patients according to their blood groups. In conclusion, individuals with blood group A had higher risk of anaemia compared to those with O and non-A phenotypes among P. falciparum malaria patients. However, there is a need to investigate the mechanism.

Genome-wide association study indicates two novel resistance loci for severe malaria

Malaria causes approximately one million fatalities per year, mostly among African children. Although highlighted by the strong protective effect of the sickle-cell trait, the full impact of human genetics on resistance to the disease remains largely unexplored. Genome-wide association (GWA) studies are designed to unravel relevant genetic variants comprehensively; however, in malaria, as in other infectious diseases, these studies have been only partly successful. Here we identify two previously unknown loci associated with severe falciparum malaria in patients and controls from Ghana, West Africa. We applied the GWA approach to the diverse clinical syndromes of severe falciparum malaria, thereby targeting human genetic variants influencing any step in the complex pathogenesis of the disease. One of the loci was identified on chromosome 1q32 within the ATP2B4 gene, which encodes the main calcium pump of erythrocytes, the host cells of the pathogenic stage of malaria parasites. The second was indicated by an intergenic single nucleotide polymorphism on chromosome 16q22.2, possibly linked to a neighbouring gene encoding the tight-junction protein MARVELD3. The protein is expressed on endothelial cells and might therefore have a role in microvascular damage caused by endothelial adherence of parasitized erythrocytes. We also confirmed previous reports on protective effects of the sickle-cell trait and blood group O. Our findings underline the potential of the GWA approach to provide candidates for the development of control measures against infectious diseases in humans.

Association of ABO blood group with severe falciparum malaria in adults: case control study and meta-analysis

Background

Erythrocyte-associated antigenic polymorphisms or their absence have perhaps evolved in the human population to protect against malarial infection. Studies in various populations consistently demonstrate that blood group 'O' confers resistance against severe falciparum infection. In India, Odisha state has one of the highest incidences of Plasmodium falciparum infection and contributes to the highest number of deaths by falciparum malaria. This study aims to evaluate the relationship between ABO blood group and severe malaria in an adult population at the tertiary care centre in Odisha.

Methods

A total of 353 P. falciparum infected subjects and 174 healthy controls were screened for ABO blood group. Falciparum-infected individuals were categorized as severe malaria and uncomplicated malaria. Severe malaria was further clinically phenotyped into cerebral malaria, non-cerebral severe malaria and multi-organ dysfunction. A meta-analysis was performed to assess the role of ABO blood group in severe malaria.

Results

Frequency of blood group 'B' was significantly higher in patients with severe malaria compared to the uncomplicated cases (P < 0.0001; OR = 4.09) and healthy controls (P < 0.0001; OR = 2.79). Irrespective of the level of clinical severity, blood group 'B' was significantly associated with cerebral malaria (P < 0.0001; OR = 5.95), multi-organ dysfunction (P < 0.0001; OR = 4.81) and non-cerebral severe malaria patients (P = 0.001; OR = 3.02) compared to the uncomplicated category. Prevalence of 'O' group in uncomplicated malaria (P < 0.0001; OR = 2.81) and healthy controls (P = 0.0003; OR = 2.16) was significantly high compared to severe malaria. Meta-analysis of previous studies, including the current one, highlighted the protective nature of blood group 'O' to severe malaria (P = 0.01). On the other hand, carriers of blood group 'A' (P = 0.04) and 'AB' (P = 0.04) were susceptible to malaria severity.

Conclusions

Results of the current study indicate that blood group 'O' is associated with reduced and 'B' blood group with increased risk of development of severe malaria in Odisha, India. Meta-analysis also supports the protective nature of blood group 'O' from severe falciparum infection.

Plasmodium falciparum malaria and the immunogenetics of ABO, HLA, and CD36 (platelet glycoprotein IV)

Plasmodium falciparum malaria has long been a killer of the young, and has selected for polymorphisms affecting not only erythrocytes, but the immunogenetics of three histocompatibility systems: ABO, human leukocyte antigen (HLA), and CD36. The ABO system is important because the original allele, encoding glycosylation with the A sugar, acts as an adhesion ligand with infected red blood cells (iRBC), thereby promoting vasoocclusion. The prevalence of blood group O, which reduces this cytoadhesion, has increased in endemic areas. Other adaptations which could mitigate A-mediated rosetting include weaker A expression and increased soluble A secretion. The role of the HLA system in malaria has been harder to verify. Although HLA-B53 and DRB1*04 may be associated with clinical outcome, HLA studies are challenged by numerous comparisons in this most polymorphic of systems, and confounded by increasingly heterogeneous populations. Certain HLA markers may also reflect linkage artefact with other malaria-relevant polymorphisms. HLA may be less important because the parasite predominantly invades a compartment which does not express HLA. Adhesion of iRBCs is also mediated by CD36, expressed on platelets, monocytes, and microvascular endothelium. CD36 on monocytes is involved in clearing iRBC, while CD36 on platelets and the endothelium may play a role in tissue sequestration. The genetics of CD36 expression are complex, and recent research is fraught with inconsistent results. The solution may lie in examining genotype-phenotype correlations, zygosity effects on differential tissue expression, or other mechanisms altering CD36 tissue expression. Carefully designed prospective studies should bridge the gap between in-vitro observations and clinical outcomes.

Frequency of ABO blood group system polymorphisms in Plasmodium falciparum malaria patients and blood donors from the Brazilian Amazon region

We investigated the ABO genotypes and heterogeneity of the O alleles in Plasmodium falciparum-infected and non-infected individuals from the Brazilian Amazon region. Sample collection took place from May 2003 to August 2005, from P. falciparum malaria patients from four endemic regions of the Brazilian Amazon. The control group consisted of donors from four blood banks in the same areas. DNA was extracted using the Easy-DNA(TM) extraction kit. ABO genotyping was performed using PCR/RFLP. There was a high frequency of ABO*O01O01. ABO*AO01 was the second most frequent genotype, and the third most frequent genotype was ABO*BO01. There were low frequencies of the ABO*O01O02, ABO*AA, ABO*AB, ABO*BB, and ABO*O02O02 genotypes. We analyzed the alleles of the O phenotype; the O(1variant) allele was the most frequent, both in malaria and non-malaria groups; consequently, the homozygous genotype O(1)(v)O(1)(v) was the most frequently observed. There was no evidence of the homozygous O(2) allele. Significant differences were not detected in the frequency of individuals with the various alleles in the comparison of the malaria patients and the general population (blood donors).

The relationship between blood groups and disease

The relative contribution of founder effects and natural selection to the observed distribution of human blood groups has been debated since blood group frequencies were shown to differ between populations almost a century ago. Advances in our understanding of the migration patterns of early humans from Africa to populate the rest of the world obtained through the use of Y chromosome and mtDNA markers do much to inform this debate. There are clear examples of protection against infectious diseases from inheritance of polymorphisms in genes encoding and regulating the expression of ABH and Lewis antigens in bodily secretions particularly in respect of Helicobacter pylori, norovirus, and cholera infections. However, available evidence suggests surviving malaria is the most significant selective force affecting the expression of blood groups. Red cells lacking or having altered forms of blood group-active molecules are commonly found in regions of the world in which malaria is endemic, notably the Fy(a-b-) phenotype and the S-s- phenotype in Africa and the Ge- and SAO phenotypes in South East Asia. Founder effects provide a more convincing explanation for the distribution of the D- phenotype and the occurrence of hemolytic disease of the fetus and newborn in Europe and Central Asia.

Genome-wide association identifies the ABO blood group as a major locus associated with serum levels of soluble E-selectin

BACKGROUND

Elevated serum soluble E-selectin levels have been associated with a number of diseases. Although E-selectin levels are heritable, little is known about the specific genetic factors involved. E-selectin levels have been associated with the ABO blood group phenotype.

METHODS AND RESULTS

We performed a high-resolution genome-wide association study of serum soluble E-selectin levels in 685 white individuals with type 1 diabetes from the Diabetes Control and Complications Trial (DCCT)/Epidemiology of Diabetes Intervention and Complications (EDIC) study to identify major loci influencing levels. Highly significant evidence for association (P=10(-29)) was observed for rs579459 near the ABO blood group gene, accounting for 19% of the variance in E-selectin levels. Levels of E-selectin were higher in O/O than O/A heterozygotes, which were likewise higher than A/A genotypes. Analysis of subgroups of A alleles reveals heterogeneity in the association, and even after this was accounted for, an intron 1 SNP remained significantly associated. We replicate the ABO association in nondiabetic individuals.

CONCLUSIONS

ABO is a major locus for serum soluble E-selectin levels. We excluded population stratification, fine-mapped the association to sub-A alleles, and also document association with additional variation in the ABO region.

The molecular genetics of blood group polymorphism

Over 300 blood group specificities on red cells have been identified, many of which are polymorphic. The molecular mechanisms responsible for these polymorphisms are diverse, though many simply represent single nucleotide polymorphisms (SNPs). Other mechanisms include the following: gene deletion; single nucleotide deletion and sequence duplication, which introduce reading-frame shifts; nonsense mutation; intergenic recombination between closely linked genes, giving rise to hybrid genes and hybrid proteins; and a SNP in the promoter region of a blood group gene. Examples of these various genetic mechanisms are taken from the ABO, Rh, Kell, and Duffy blood group systems. Null phenotypes, in which no antigens of a blood group system are expressed, are not generally polymorphic, but provide good examples of the effect of inactivating mutations on blood group expression. As natural human 'knock-outs', null phenotypes provide useful clues to the functions of blood group antigens. Knowledge of the molecular backgrounds of blood group polymorphisms provides a means to predict blood group phenotypes from genomic DNA. This has two main applications in transfusion medicine: determination of foetal blood groups to assess whether the foetus is at risk from haemolytic disease and ascertainment of blood group phenotypes in multiply transfused, transfusion-dependent patients, where serological tests are precluded by the presence of donor red cells. Other applications are being developed for the future.

Rosetting in Plasmodium falciparum: a cytoadherence phenotype with multiple actors

The capacity of Plasmodium falciparum-infected red blood cells to bind uninfected red blood cells ("rosetting") has been associated with high parasite density in numerous geographic areas and with severe malaria in African children. We summarize here the associations that have emerged from field studies and describe the various experimental models of rosetting that have been developed. A variety of erythrocyte receptors, several serum factors and a number of rosette-mediating PfEMP1 adhesins have been identified. Several var genes code for rosette-forming PfEMP1 adhesins in each P. falciparum genome, so that each clonal line has the capacity to generate distinct types of rosettes. To clarify their respective role in malaria pathogenesis, each of the multiple ligand/receptor interactions should be further studied for fine specificity, binding affinity and the impact of the large population polymorphism of the parasite variant repertoires should be assessed. Interestingly, some major human erythrocyte surface polymorphisms have been identified as affecting rosette formation, consistent with a role for rosetting in life-threatening falciparum malaria.