ABO O blood group as a risk factor for platelet reactivity in heparin-induced thrombocytopenia

ABO Blood Type and Short-Term Mortality in Patients With Infection-Associated Disseminated Intravascular Coagulation

BACKGROUND

Disseminated intravascular coagulation (DIC) is a devastating disease of the coagulation system. We examined the association between ABO blood type and short-term mortality in patients with infection-associated DIC.

METHODS

The study cohort was drawn from the Danish Disseminated Intravascular Coagulation (DANDIC) cohort. Our subcohort was restricted to patients with infection-associated DIC. All-cause 30-day and 90-day mortality were computed by Kaplan-Meier estimates and odds ratios between ABO blood types were examined using logistic regression analysis adjusted for age, sex, comorbidity, and location of infection. Blood type O was used as a reference.

RESULTS

The DANDIC cohort included 3023 patients with DIC. Among these, 1853 (61%) had infection-associated DIC. Data on ABO blood type were unavailable in 34 patients (1.8%), who were excluded. The median age was 68 years and 58.2% were males. The 30-day mortality ranged between 38.6% and 42.5% and the 30-day mortality odds ratios were 1.15 (95% confidence interval (CI), 0.92-1.42) for blood type A; 0.84 (95% CI, 0.49-1.43) for AB; and 0.95 (95% CI, 0.67-1.33) for B compared to blood type O.

CONCLUSIONS

We found no clinically meaningful difference in short-term mortality between the various ABO blood types in patients with infection-associated DIC.

Associations between ABO, FUT2 and chronic pancreatitis: A comprehensive meta-analysis of multiple cohorts and public biobanks

OBJECTIVES

Associations of ABO blood group specifying transferases A/B (ABO) and fucosyltransferase 2 (FUT2) with CP remain inconclusive. We aimed to comprehensively investigate the associations by Chinese sequencing cohorts and external cohorts.

METHODS

First, we analyzed the distributions of ABO blood groups and FUT2 status, along with lead single nucleotide polymorphisms (SNPs) at ABO (rs8176693 C/T) and FUT2 (rs632111 A/G) gene loci in Chinese low-coverage whole-genome sequencing discovery cohort. Subsequently, we investigated the associations of CP with ABO and FUT2 SNPs in Chinese whole-exome sequencing validation cohort and three public biobanks (FinnGen, UK Biobank, and BioBank Japan). Finally, comprehensive meta-analysis was performed by integrating data from two Chinese cohorts, reported cohorts and public biobanks.

RESULTS

Firstly, in Chinese discovery cohort, the distribution of blood types in CP patients showed no significant difference compared to healthy controls, and similar results were observed in subgroup analyses and in meta-analysis with the reported cohorts. Secondly, results indicated no association between rs8176693 or rs632111 and CP in Chinese cohorts and meta-analysis of three biobanks, though ABO SNP was found to be significantly associated with CP in UK Biobank (odds ratio [OR] = 1.27, P = 0.04). Finally, no association was observed between rs8176693 (OR = 1.03, P = 0.29) or rs632111 (OR = 1.04, P = 0.10) and CP in comprehensive meta-analysis.

CONCLUSIONS

No association was found between lead SNPs of ABO or FUT2 and CP in meta-analysis, nor was there an association between ABO blood group or FUT2 secretor status and CP in Chinese cohort. ABO and FUT2 might play limited role in CP development.

ABO Blood Group and Risk Associated With Sepsis-Associated Thrombocytopenia: A Single-Center Retrospective Study

OBJECTIVES

This study aimed to investigate the relationship between ABO blood group and sepsis-associated thrombocytopenia (SAT).

DESIGN AND SETTING

The primary outcome was SAT within the first 72 hours of ICU admission.

PATIENTS

The retrospective study included 9113 patients diagnosed with sepsis from January 2014 to December 2022. A total of 6296 patients eventually were included into the study, who were divided into four groups based on ABO blood group.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

A total of 2494 patients (39.6%) were diagnosed with SAT, and 712 (11.3%) of them experiencing severe SAT. The occurrence of SAT among the ABO blood groups was significantly lower in AB blood group compared with the other groups (p = 0.032). Individuals in AB blood group were less likely to experience severe SAT (p = 0.028). In multivariate analysis, B blood group (odds ratio [OR], 1.32; 95% CI, 1.05-1.67) and O (OR, 1.37; 95% CI, 1.09-1.72) were significantly associated with a higher occurrence of SAT compared with AB blood group. In multivariate analyses, A blood group (OR, 1.68; 95% CI, 1.16-2.42), B blood group (OR, 1.74; 95% CI, 1.74-2.50), and O blood group (OR, 1.72; 95% CI, 1.20-2.48) remained significantly risk factors associated with a higher occurrence of severe SAT compared with AB blood group.

CONCLUSIONS

B blood group and O were associated with an increased risk of SAT and severe SAT.

Association of Metal Cations with the Anti-PF4/Heparin Antibody Response in Heparin-Induced Thrombocytopenia

Heparin-induced thrombocytopenia (HIT) is an antibody-mediated immune response against complexes of heparin and platelet factor 4 (PF4). The electrostatic interaction between heparin and PF4 is critical for the anti-PF4/heparin antibody response seen in HIT. The binding of metal cations to heparin induces conformational changes and charge neutralization of the heparin molecule, and cation-heparin binding can modulate the specificity and affinity for heparin-binding partners. However, the effects of metal cation binding to heparin in the context of anti-PF4/heparin antibody response have not been determined. Here, we utilized inductively coupled plasma mass spectrometry (ICP-MS) to quantify 16 metal cations in patient plasma and tested for correlation with anti-PF4/heparin IgG levels and platelet count after clinical suspicion of HIT in a cohort of heparin-treated patients. The average age of the cohort (n = 32) was 60.53 (SD = 14.31) years old, had a mean anti-PF4/heparin antibody optical density [OD405] of 0.93 (SD = 1.21) units, and was primarily female (n = 23). Patients with positive anti-PF4/heparin antibody test results (OD405 ≥ 0.5 units) were younger, had increased weight and BMI, and were more likely to have a positive serotonin release assay (SRA) result compared to antibody-negative patients. We observed statistical differences between antibody-positive and -negative groups for sodium and aluminum and significant correlations of anti-PF4/heparin antibody levels with sodium and silver. While differences in sodium concentrations were associated with antibody-positive status and correlated with antibody levels, no replication was performed. Additional studies are warranted to confirm our observed association, including in vitro binding studies and larger observational cohorts.

Cardiovascular Pharmacogenetics: From Discovery of Genetic Association to Clinical Adoption of Derived Test

Recent breakthroughs in human genetics and in information technologies have markedly expanded our understanding at the molecular level of the response to drugs, i.e., pharmacogenetics (PGx), across therapy areas. This review is restricted to PGx for cardiovascular (CV) drugs. First, we examined the PGx information in the labels approved by regulatory agencies in Europe, Japan, and North America and related recommendations from expert panels. Out of 221 marketed CV drugs, 36 had PGx information in their labels approved by one or more agencies. The level of annotations and recommendations varied markedly between agencies and expert panels. Clopidogrel is the only CV drug with consistent PGx recommendation (i.e., "actionable"). This situation prompted us to dissect the steps from discovery of a PGx association to clinical translation. We found 101 genome-wide association studies that investigated the response to CV drugs or drug classes. These studies reported significant associations for 48 PGx traits mapping to 306 genes. Six of these 306 genes are mentioned in the corresponding PGx labels or recommendations for CV drugs. Genomic analyses also highlighted the wide between-population differences in risk allele frequencies and the individual load of actionable PGx variants. Given the high attrition rate and the long road to clinical translation, additional work is warranted to identify and validate PGx variants for more CV drugs across diverse populations and to demonstrate the utility of PGx testing. To that end, pre-emptive PGx combining genomic profiling with electronic medical records opens unprecedented opportunities to improve healthcare, for CV diseases and beyond. SIGNIFICANCE STATEMENT: Despite spectacular breakthroughs in human molecular genetics and information technologies, consistent evidence supporting PGx testing in the cardiovascular area is limited to a few drugs. Additional work is warranted to discover and validate new PGx markers and demonstrate their utility. Pre-emptive PGx combining genomic profiling with electronic medical records opens unprecedented opportunities to improve healthcare, for CV diseases and beyond.

Association of Metal Cations with the Anti-PF4/Heparin Antibody Response in Heparin-Induced Thrombocytopenia

Heparin-induced thrombocytopenia (HIT) is an antibody-mediated immune response against complexes of heparin and platelet factor 4 (PF4). The electrostatic interaction between heparin and PF4 is critical for the anti-PF4/heparin antibody response seen in HIT. The binding of metal cations to heparin induces conformational changes and charge neutralization of the heparin molecule, and cation-heparin binding can modulate the specificity and affinity for heparin-binding partners. However, the effects of metal cation binding to heparin in the context of anti-PF4/heparin antibody response have not been determined. Here, we utilized inductively coupled plasma mass spectrometry (ICP-MS) to quantify 16 metal cations in patient plasma and tested for correlation with anti-PF4/heparin IgG levels and platelet count after clinical suspicion of HIT in a cohort of heparin-treated patients. The average age of the cohort (n = 32) was 60.53 (SD = 14.31) years old, had a mean anti-PF4/heparin antibody optical density [OD405] of 0.93 (SD = 1.21) units and was primarily female (n = 23). Patients with positive anti-PF4/heparin antibody test results (OD405 ≥ 0.5 units) were younger, had increased weight and BMI, and were more likely to have a positive serotonin release assay (SRA) result compared to antibody negative patients. We observed statistical differences between antibody positive and negative groups for sodium and aluminum and significant correlations of anti-PF4/heparin antibody levels with sodium and silver. While differences in sodium concentrations were associated with antibody positive status and correlated with antibody levels, no replication was performed. Additional studies are warranted to confirm our observed association, including in vitro binding studies and larger observational cohorts.

Being precise with anticoagulation to reduce adverse drug reactions: are we there yet?

Anticoagulants are potent therapeutics widely used in medical and surgical settings, and the amount spent on anticoagulation is rising. Although warfarin remains a widely prescribed oral anticoagulant, prescriptions of direct oral anticoagulants (DOACs) have increased rapidly. Heparin-based parenteral anticoagulants include both unfractionated and low molecular weight heparins (LMWHs). In clinical practice, anticoagulants are generally well tolerated, although interindividual variability in response is apparent. This variability in anticoagulant response can lead to serious incident thrombosis, haemorrhage and off-target adverse reactions such as heparin-induced thrombocytopaenia (HIT). This review seeks to highlight the genetic, environmental and clinical factors associated with variability in anticoagulant response, and review the current evidence base for tailoring the drug, dose, and/or monitoring decisions to identified patient subgroups to improve anticoagulant safety. Areas that would benefit from further research are also identified. Validated variants in VKORC1, CYP2C9 and CYP4F2 constitute biomarkers for differential warfarin response and genotype-informed warfarin dosing has been shown to reduce adverse clinical events. Polymorphisms in CES1 appear relevant to dabigatran exposure but the genetic studies focusing on clinical outcomes such as bleeding are sparse. The influence of body weight on LMWH response merits further attention, as does the relationship between anti-Xa levels and clinical outcomes. Ultimately, safe and effective anticoagulation requires both a deeper parsing of factors contributing to variable response, and further prospective studies to determine optimal therapeutic strategies in identified higher risk subgroups.

Laboratory and demographic predictors of functional assay positive status in suspected heparin-induced thrombocytopenia: A multicenter retrospective cohort study

Heparin-induced thrombocytopenia (HIT) is an antibody-mediated immune response against platelet factor 4 (PF4) bound to heparin anticoagulants. A priori identification of patients at-risk for HIT remains elusive and a number of risk factors have been identified, but these associations and their effect sizes have limited validation in large cohorts of suspected HIT patients. The aim of this study was to investigate existing anti-PF4/heparin antibody thresholds and model the relationship of demographic variables and anti-PF4/heparin antibody levels with functional assay positivity across multiple institutions in the absence of detailed clinical data. In a large collection of suspected HIT patients (n = 8904), we tested for associations between laboratory and demographic variables and functional assay positive status as well as anti-PF4/heparin antibody levels. We also tested for correlation between IgG-specific and polyspecific (IgG/IgA/IgM) anti-PF4/heparin antibody values and their ability to predict functional assay positive status using area under the receiver operating characteristic (AUROC). Logistic regression identified increasing anti-PF4/heparin antibody OD levels (OR = 51.84 [37.27-74.34], p < 2.0 × 10-16) and female sex (OR = 1.47 [1.19-1.82], p = 3.5 × 10-4) as risk factors for positive functional assay in the largest cohort with consistent effect sizes in two other cohorts. In a subset of 1175 patients, polyspecific and IgG-specific anti-PF4/heparin antibody values were heterogeneous (mean coefficient of variation = 31.9 %), but strongly correlated (rho = 0.878; p < 2 × 10-16) with similar prediction of functional assay positivity (polyspecific AUROC = 0.976 and IgG-specific AUROC = 0.980). Thus, we recapitulate previously identified risk factors of functional assay positivity, providing precise effect sizes in a large observational population of suspected HIT patients. Our data reinforce the necessity of functional assay confirmation and suggest that, despite heterogeneity, polyspecific and IgG-specific anti-PF4/heparin antibody assays predict functional assay positive status similarly, even in the absence of 4Ts scores and detailed clinical data.

ABO blood group antigens and differential glycan expression: Perspective on the evolution of common human enzyme deficiencies

Enzymes catalyze biochemical reactions and play critical roles in human health and disease. Enzyme variants and deficiencies can lead to variable expression of glycans, which can affect physiology, influence predilection for disease, and/or directly contribute to disease pathogenesis. Although certain well-characterized enzyme deficiencies result in overt disease, some of the most common enzyme deficiencies in humans form the basis of blood groups. These carbohydrate blood groups impact fundamental areas of clinical medicine, including the risk of infection and severity of infectious disease, bleeding risk, transfusion medicine, and tissue/organ transplantation. In this review, we examine the enzymes responsible for carbohydrate-based blood group antigen biosynthesis and their expression within the human population. We also consider the evolutionary selective pressures, e.g. malaria, that may account for the variation in carbohydrate structures and the implications of this biology for human disease.

Genome-wide association study of platelet factor 4/heparin antibodies in heparin-induced thrombocytopenia

Heparin, a widely used anticoagulant, carries the risk of an antibody mediated adverse drug reaction, heparin-induced thrombocytopenia (HIT). A subset of heparin-treated patients produces detectable levels of antibodies against complexes of heparin bound to circulating platelet factor 4 (PF4). Using a genome-wide association study (GWAS) approach, we aimed to identify genetic variants associated with anti-PF4/heparin antibodies that account for the variable antibody response seen in HIT. We performed a GWAS on anti-PF4/heparin antibody levels determined via polyclonal enzyme-linked immunosorbent assays (ELISA). Our discovery cohort (n=4237) and replication cohort (n=807) constituted patients with European ancestry and clinical suspicion of HIT with cases confirmed via functional assay. Genome-wide significance was considered at α=5x10-8. No variants were significantly associated with anti-PF4/heparin antibody levels in the discovery cohort at a genome-wide significant level. Secondary GWAS analyses included identification of variants with suggestive associations in the discovery cohort (α=1x10-4). The top variant in both cohorts was rs1555175145 (discovery β=-0.112[0.018], p=2.50x10-5; replication β=-0.104[0.051], p=0.041). In gene set enrichment analysis (GSEA), three gene sets reached false discovery rate-adjusted significance (q<0.05) in both discovery and replication cohorts: "Leukocyte Transendothelial Migration," "Innate Immune Response," and "Lyase Activity." Our results indicate that genomic variation is not significantly associated with anti-PF4/heparin antibody levels. Given our power to identify variants with moderate frequencies and effect sizes, this evidence suggests genetic variation is not a primary driver of variable antibody response in heparin-treated patients with European ancestry.