Genome-wide association study identifies HLA-DR variants conferring risk of HBV-related acute-on-chronic liver failure

Human Leukocyte Antigen Polymorphism HLA-A*24:02 is Associated with Acute Liver Disease in HBV-Infected Han Chinese Adults

BACKGROUND

Whether polymorphic Human Leukocyte Antigen (HLA)-A, HLA-B and HLA-DRB1 alleles were associated with acute liver disease after hepatitis B virus (HBV) infections was investigated.

METHODS

In this study, from initially 100 participants in each group, HLA-A, HLA-B and HLA-DRB1 sequences were available from 86 acute hepatitis B (AHB) patients and from 84 HBV-resistant individuals (controls), using sequencing-based typing allele groups and alleles that exhibited differences in distribution between the case and control groups were subjected to chi-squared and logistic regression analyses to identify those associated with AHB. A dose response analysis was also performed on the effect of HLA-A*24:02 allele number on acute liver disease following HBV infection.

RESULTS

The frequency distribution of HLA-B and HLA-DRB1 alleles in the control group were in Hardy-Weinberg Equilibrium (P > .05). HLA-A*24:02 (χ2 = 6.949, P = .008) occurred most frequently in the AHB and HLA-DRB1*12:02 (χ2 = 7.768, P = .005) in the control group. With adjustment for sex, the logistic regression model showed that the HLA-A*24:02 allele was significantly associated with AHB liver injury (P = .0326, OR = 2.270, 95% CI: 1.070-4.816), whereas the other HLA-A, HLA-B, and HLA-DRB1 alleles were not (P > .05). A linear response was observed for the association between HLA-A*24:02 allele number and acute liver disease after HBV infections (χ2 = 4.428, P = .025).

CONCLUSION

The HLA-A*24:02 allele may influence the severity of the cellular response to HBV infection, increasing the elimination of HBV-infected hepatocytes. The HLA-A*24:02 allele may be a potential screening marker for identifying people or regional populations in China at higher risk of acute liver disease following HBV infection.

A Lower HCC Incidence in Chronic HBV-Infected Patients Recovered from Acute-on-Chronic Liver Failure: A Prospective Cohort Study

Background

Activation of chronic hepatitis B virus (HBV) infection is an important cause of acute-on-chronic liver failure (ACLF). However, the effect of HBV-ACLF episode on hepatocellular carcinoma (HCC) occurrence remains largely unknown.

Methods

A total of 769 HBV-ACLF patients and 2114 HBV-related chronic liver disease (HBV-CLD) patients diagnosed between August 1998 and December 2011 were enrolled in this prospective cohort study. Of the HBV-CLD patients, 380 received lifetime antiviral treatment with nucleos(t)ide analogues. Propensity score matching was applied to reduce baseline differences between HBV-ACLF and HBV-CLD cohorts.

Results

The survival rate of HBV-ACLF patients was 53.6%, 50.3%, 47.8%, and 46.2% at 90-day, 1-year, 5-year, and 10-year, respectively. The cumulative incidence of HCC was lower in HBV-ACLF cohort with 369 eligible patients survived for >90 days than in HBV-CLD cohort with the 380 patients (5.77/1,000 vs. 9.78/1,000 person-years, p = 0.0497). HBV-ACLF episode decreased HCC risk regardless of liver cirrhosis, and in patients without family history of HCC. Multivariate Cox analyses indicated that male, increasing age, liver cirrhosis, and platelet count (≤100 × 10⁹/L) increased, whereas HBV-ACLF episode decreased, HCC risk independently. In the propensity score-matched cohorts, HBV-ACLF episode reduced HCC incidence (10.20/1,000 vs. 4.66/1,000 person-years, p = 0.0326). The area under curve of nomogram was 0.812 for 3-year HCC probability.

Conclusions

HBV-ACLF episode decreases HCC occurrence in chronic HBV patients. Older age and liver cirrhosis independently increased HCC occurrence. A nomogram-enrolled episode of ACLF reliably predicts the occurrence of HCC.

The Immune Pathogenesis of Acute-On-Chronic Liver Failure and the Danger Hypothesis

Acute-on-chronic liver failure (ACLF) is a group of clinical syndromes related to severe acute liver function impairment and multiple-organ failure caused by various acute triggering factors on the basis of chronic liver disease. Due to its severe condition, rapid progression, and high mortality, it has received increasing attention. Recent studies have shown that the pathogenesis of ACLF mainly includes direct injury and immune injury. In immune injury, cytotoxic T lymphocytes (CTLs), dendritic cells (DCs), and CD4⁺ T cells accumulate in the liver tissue, secrete a variety of proinflammatory cytokines and chemokines, and recruit more immune cells to the liver, resulting in immune damage to the liver tissue, massive hepatocyte necrosis, and liver failure, but the key molecules and signaling pathways remain unclear. The “danger hypothesis” holds that in addition to the need for antigens, damage-associated molecular patterns (DAMPs) also play a very important role in the occurrence of the immune response, and this hypothesis is related to the pathogenesis of ACLF. Here, the research status and development trend of ACLF, as well as the mechanism of action and research progress on various DAMPs in ACLF, are summarized to identify biomarkers that can predict the occurrence and development of diseases or the prognosis of patients at an early stage.

Hepatitis B Virus Reactivation Increased the Risk of Developing Hepatic Failure and Mortality in Cirrhosis With Acute Exacerbation

Background and Aims

Hepatitis B virus (HBV) reactivation is a serious condition and has been extensively described in chemotherapeutic immunosuppressive population. However, little is known about HBV reactivation in immunocompetent patients with chronic hepatitis B (CHB). In this study, we evaluated the prevalence and the clinical significance of HBV reactivation in CHB patients with acute exacerbations.

Method

Patients were screened from two prospective multicenter observational cohorts (CATCH-LIFE cohort). A total of 1,020 CHB patients with previous antiviral treatment history were included to assess the prevalence, risk factors, clinical characteristics of HBV reactivation, and its influence on the progression of chronic liver disease.

Results

The prevalence of HBV reactivation was 51.9% in CHB patients with acute exacerbations who had antiviral treatment history in our study. Among the 529 patients with HBV reactivation, 70.9% of them were triggered by discontinued antiviral treatment and 5.9% by nucleos(t)ide analogs (NUCs) resistance. The prevalence of antiviral treatment disruption and NUCs resistance in patients with HBV reactivation is much higher than that in the patients without (70.9% vs. 0.2%, and 5.9% vs. 0, respectively, both p < 0.001). Stratified and interaction analysis showed that HBV reactivation was correlated with high short-term mortality in cirrhosis subgroup (HR = 2.1, p < 0.001). Cirrhotic patients with HBV reactivation had a significantly higher proportion of developing hepatic failure (45.0% vs. 20.3%, p < 0.001), acute-on-chronic liver failure (ACLF; 31.4% vs. 21.8%, p = 0.005), and short-term death (14.0% vs. 5.9% for 28-day, and 23.3% vs. 12.4% for 90-day, both p < 0.001) than those without. HBV reactivation is an independent risk factor of 90-day mortality for cirrhosis patients (OR = 1.70, p = 0.005), as well as hepatic encephalopathy, ascites, and bacterial infection.

Conclusion

This study clearly demonstrated that there was a high prevalence of HBV reactivation in CHB patients, which was mainly triggered by discontinued antiviral treatment. The HBV reactivation strongly increased the risk of developing hepatic failure, ACLF and short-term death in HBV-related cirrhotic patients, which may suggest that HBV reactivation would be a new challenge in achieving the WHO target of 65% reduction in mortality from hepatitis B by 2030.

Critical Updates on Chronic Hepatitis B Virus Infection in 2021

Chronic hepatitis B virus (HBV) infection is a global healthcare burden in the form of chronic liver disease, cirrhosis, liver failure and liver cancer. There is no definite cure for the virus and even though extensive vaccination programs have reduced the burden of liver disease in the future population, treatment options to eradicate the virus from the host are still lacking. In this review, we discuss in detail current updates on the structure and applied biology of the virus in the host, examine updates to current treatment and explore novel and state-of-the-art therapeutics in the pipeline for management of chronic HBV. Furthermore, we also specifically review clinical updates on HBV-related acute on chronic liver failure (ACLF). Current treatments for chronic HBV infection have seen important updates in the form of considerations for treating patients in the immune tolerant phase and some clarity on end points for treatment and decisions on finite therapy with nucleos(t)ide inhibitors. Ongoing cutting-edge research on HBV biology has helped us identify novel target areas in the life cycle of the virus for application of new therapeutics. Due to improvements in the area of genomics, the hope for therapeutic vaccines, vector-based treatments and focused management aimed at targeting host integration of the virus and thereby a total cure could become a reality in the near future. Newer clinical prognostic tools have improved our understanding of timing of specific treatment options for the catastrophic syndrome of ACLF secondary to reactivation of HBV. In this review, we discuss in detail pertinent updates regarding virus biology and novel therapeutic targets with special focus on the appraisal of prognostic scores and treatment options in HBV-related ACLF.

Leveraging omics to understand the molecular basis of acute-on-chronic liver failure

Acute-on-chronic liver failure (ACLF) is a complex syndrome that develops in patients with acutely decompensated cirrhosis. In this condition, dysbalanced immune function and excessive systemic inflammation are closely associated with organ failure and high short-term mortality. In this review, we describe how omic technologies have contributed to the characterization of the hyperinflammatory state in patients with acutely decompensated cirrhosis developing ACLF, with special emphasis on the role of metabolomics, lipidomics and transcriptomics in profiling the triggers (pathogen- and damage-associated molecular patterns [PAMPs and DAMPs]) and effector molecules (cytokines, chemokines, growth factors and bioactive lipid mediators) that lead to activation of the innate immune system. This review also describes how omic approaches can be invaluable tools to accelerate the identification of novel biomarkers that could guide the implementation of novel therapies/interventions aimed at protecting these patients from excessive systemic inflammation and organ failure.

Copy number gain of pro-inflammatory genes in patients with HBV-related acute-on-chronic liver failure

Background

Host genetic factors such as single nucleotide variations may play a crucial role in the onset and progression of HBV-related acute-on-chronic liver failure (ACLF). However, the underlying genomic copy number variations (CNVs) involved in the pathology are currently unclear.

Methods

We genotyped two cohorts with 389 HBV-related ACLF patients and 391 asymptomatic HBV carriers (AsCs), and then carried out CNV-based global burden analysis and a genome-wide association study (GWAS).

Results

For 1874 rare CNVs, HBV-related ACLF patients exhibited a high burden of deletion segments with a size of 100–200 kb (P value = 0.04), and the related genes were significantly enriched in leukocyte transendothelial migration pathway (P value = 4.68 × 10^–3). For 352 common CNVs, GWAS predicted 17 significant association signals, and the peak one was a duplication segment located on 1p36.13 (~ 38 Kb, P value = 1.99 × 10^–4, OR = 2.66). The associated CNVs resulted in more copy number of pro-inflammatory genes (MST1L, DEFB, and HCG4B) in HBV-related ACLF patients than in AsC controls.

Conclusions

Our results suggested that the impact of host CNV on HBV-related ACLF may be through decreasing natural immunity and enhancing host inflammatory response during HBV infection. The findings highlighted the potential importance of gene dosage on excessive hepatic inflammation of this disease.

Systematic analysis on multiple Gene Expression Omnibus data sets reveals fierce immune response in hepatitis B virus-related acute liver failure

Acute liver failure (ALF) caused by hepatitis B virus (HBV) is common type of liver failure in the world, with high morbidity and mortality rates. However, the prevalence, genetic background and factors determining the development of HBV‐related ALF are rarely studied. In this study, we examined three Gene Expression Omnibus (GEO) data sets by bioinformatics analysis to identify differentially expressed genes (DEGs), key biological processes and pathways. Immune infiltration analysis showed high immune cells infiltration in HBV‐related ALF tissue. We then confirmed natural killer cells and macrophages infiltration in clinical samples by immunohistochemistry assay, implying these cells play a significant role in HBV‐ALF. We found 1277 genes were co‐up‐regulated and that 1082 genes were co‐down‐regulated in the 3 data sets. Inflammation‐related pathways were enriched in the co‐up‐regulated genes and synthetic metabolic pathways were enriched in the co‐down‐regulated genes. WGCNA also revealed a key module enriching in immune inflammation response and identified 10 hub genes, differentially expressed in an independent data set. In conclusion, we identified fierce immune inflammatory response to elucidate the immune‐driven mechanism of HBV‐ALF and 10 hub genes based on gene expression profiles.

The fibrogenic process and the unleashing of acute-on-chronic liver failure

Acute-on-chronic liver failure (ACLF) is a life-threatening condition characterized by a rapid deterioration of previously well-compensated chronic liver diseases. One of the main obstacles in ACLF is the lack of knowledge of the pathogenesis and specific broad-spectrum treatments. An excessive systemic inflammatory response has been proposed to explain the pathogenesis of ACLF; this hypothesis involves stellate cells, which are implicated in many liver homeostatic functions that include vitamin A storage, regulation of sinusoidal blood flow, local inflammation, maintenance of the hepatocyte phenotype and extracellular matrix remodeling. However, when there is damage to the liver, these cells are the main target of the inflammatory stimulus, as a result, the secretion of the extracellular matrix is altered. Activated hepatic stellate cells raise the survival of neutrophils by the stimulation of granulocytes colonies and macrophages, which exacerbates liver inflammation and promotes damage to hepatocytes. Elevation of pathogen-associated molecular patterns is related to liver damage by different pathophysiological mechanisms of decompensation, showing ballooning degeneration and cell death with a predominance of cholestatic infection. Moreover, patients with ACLF present a marked elevation of C-reactive protein together with an elevation of the leukocyte count. Chronic liver disease is a complex pathological state with a heterogeneous pathophysiology in which genetic factors of the host and external triggers interact and culminate in hepatic insufficiency. The better understanding of such interactions should lead to a better comprehension of the disease and to the discovery of new treatment targets that will make acute decompensations preventable and even decrease mortality.

Addressing Profiles of Systemic Inflammation Across the Different Clinical Phenotypes of Acutely Decompensated Cirrhosis

Background: Patients with acutely decompensated cirrhosis (AD) may or may not develop acute-on-chronic liver failure (ACLF). ACLF is characterized by high-grade systemic inflammation, organ failures (OF) and high short-term mortality. Although patients with AD cirrhosis exhibit distinct clinical phenotypes at baseline, they have low short-term mortality, unless ACLF develops during follow-up. Because little is known about the association of profile of systemic inflammation with clinical phenotypes of patients with AD cirrhosis, we aimed to investigate a battery of markers of systemic inflammation in these patients. Methods: Upon hospital admission baseline plasma levels of 15 markers (cytokines, chemokines, and oxidized albumin) were measured in 40 healthy controls, 39 compensated cirrhosis, 342 AD cirrhosis, and 161 ACLF. According to EASL-CLIF criteria, AD cirrhosis was divided into three distinct clinical phenotypes (AD-1: Creatinine<1.5, no HE, no OF; AD-2: creatinine 1.5-2, and or HE grade I/II, no OF; AD-3: Creatinine<1.5, no HE, non-renal OF). Results: Most markers were slightly abnormal in compensated cirrhosis, but markedly increased in AD. Patients with ACLF exhibited the largest number of abnormal markers, indicating "full-blown" systemic inflammation (all markers). AD-patients exhibited distinct systemic inflammation profiles across three different clinical phenotypes. In each phenotype, activation of systemic inflammation was only partial (30% of the markers). Mortality related to each clinical AD-phenotype was significantly lower than mortality associated with ACLF (p < 0.0001 by gray test). Among AD-patients baseline systemic inflammation (especially IL-8, IL-6, IL-1ra, HNA2 independently associated) was more intense in those who had poor 28-day outcomes (ACLF, death) than those who did not experience these outcomes. Conclusions: Although AD-patients exhibit distinct profiles of systemic inflammation depending on their clinical phenotypes, all these patients have only partial activation of systemic inflammation. However, those with the most extended baseline systemic inflammation had the highest the risk of ACLF development and death.

Diverse Effects of the NTCP p.Ser267Phe Variant on Disease Progression During Chronic HBV Infection and on HBV preS1 Variability

The sodium taurocholate co-transporting polypeptide (NTCP) acts as a cellular receptor for the hepatitis B virus (HBV) infection on host hepatocytes. We aim to investigate how the NTCP p.Ser267Phe variant affects HBV-related disease progression and analyze viral genomic variability under a host genetic background carrying the p.Ser267Phe variant. A total of 3187 chronic hepatitis B (CHB) patients were enrolled and genotyped for the p.Ser267Phe variant. The variant's association with disease progression was evaluated by logistic regression analysis. We also enrolled 83 treatment-naive CHB patients to analyze the variability of the HBV preS1 region. The frequency of the NTCP p.Ser267Phe variant was significantly lower in patients diagnosed with acute-on-chronic liver failure [OR (95% CI) = 0.33 (0.18-0.58), P = 1.34 × 10-4], cirrhosis [OR (95% CI) = 0.47 (0.31-0.72), P = 4.04 × 10-4], and hepatocellular carcinoma [OR (95% CI) = 0.54 (0.34-0.86), P = 9.83 × 10-3] as compared with CHB controls under the additive model after adjustment. Furthermore, the percentage of amino acid mutations in HBV preS1 region was significantly higher in the NTCP p.Ser267Phe heterozygote group than in the NTCP wild type homozygote group (P < 0.05). We herein demonstrate that the NTCP p.Ser267Phe variant is a protective factor reducing CHB patient risk for liver failure, cirrhosis, and hepatocellular carcinoma. A host genetic background carrying NTCP p.Ser267Phe exerts selective pressure on the virus, leading to more variability.

Host genetic factors affecting hepatitis B infection outcomes: Insights from genome-wide association studies

The clinical outcome of Hepatitis B Virus (HBV) infection depends on the success or failure of the immune responses to HBV, and varies widely among individuals, ranging from asymptomatic self-limited infection, inactive carrier state, chronic hepatitis, cirrhosis, hepatocellular carcinoma, to liver failure. Genome-wide association studies (GWAS) identified key genetic factors influencing the pathogenesis of HBV-related traits. In this review, we discuss GWAS for persistence of HBV infection, antibody response to hepatitis B vaccine, and HBV-related advanced liver diseases. HBV persistence is associated with multiple genes with diverse roles in immune mechanisms. The strongest associations are found within the classical human leukocyte antigen (HLA) genes, highlighting the central role of antigen presentation in the immune response to HBV. Associated variants affect both epitope binding specificities and expression levels of HLA molecules. Several other susceptibility genes regulate the magnitude of adaptive immune responses, determining immunity vs tolerance. HBV persistence and nonresponse to vaccine share the same risk variants, implying overlapping genetic bases. On the other hand, the risk variants for HBV-related advanced liver diseases are largely different, suggesting different host-virus dynamics in acute vs chronic HBV infections. The findings of these GWAS are likely to pave the way for developing more effective preventive and therapeutic interventions by personalizing the management of HBV infection.

Acute-on-chronic liver failure in chronic hepatitis B: an update

Acute-on-chronic liver failure is a common pattern of end-stage liver disease in clinical practice and occurs frequently in patients with chronic hepatitis B or HBV-related cirrhosis. New progress in recent years leads to a better understanding of this disease. Areas covered: This review updates the current comprehensive knowledge about HBV-ACLF from epidemiological studies, experimental studies, and clinical studies and provide new insights into the definition, diagnostic criteria, epidemiology, nature history, pathogenesis, treatment and prognostication of HBV-ACLF. Expert commentary: Patients with chronic hepatitis B or HBV-related cirrhosis are at risk of developing acute-on-chronic liver failure, with multi-organ failure and high short-term mortality. The precipitating events can be intra-hepatic or extra-hepatic and the underlying chronic liver injury can be cirrhotic or non-cirrhotic. Host and viral factors contribute to the susceptibility of developing HBV-ACLF. Systemic inflammation is the driver of HBV-ACLF, which can be attributed to non-sterile and sterile factors. Liver transplantation is the definitive treatment for HBV-ACLF. Cell therapy is a promising alternative to LT, but requires validation and still has concern of long-term safety. Other medical therapies, such as nucleoside analogue, artificial liver supporting and glucocorticoid may improve survival in a specific subgroup. New scoring systems improve the accuracy of prognostication in HBV-ACLF, which is critical for early identification of candidates for LT.

Characteristics of systemic inflammation in hepatitis B-precipitated ACLF: Differentiate it from No-ACLF

BACKGROUND & AIMS

Patients with severe exacerbation of chronic hepatitis B (SE-CHB) are at risk of developing acute-on-chronic liver failure (ACLF). Systemic inflammation (SI) is a major driver of ACLF. The aim of this study was to identify characteristics of SI in hepatitis B-precipitated-ACLF (HB-ACLF), which may be distinct from No-ACLF patients with SE-CHB.

METHODS

Two cohorts of patients with SE-CHB were enrolled in two tertiary hospitals. The associations between circulating leucocyte counts/subsets and ACLF progression and prognoses were analysed in Cohort A. Cytokine measurements, leucocyte phenotyping and whole blood transcriptomic analyses were performed using peripheral blood samples obtained from patients in Cohort B.

RESULTS

Circulating leucocyte counts were higher in the HB-ACLF patients than in the No-ACLF patients (P < .001). Peripheral neutrophilic leucocytosis and monocytosis were associated with lymphopenia. The neutrophil-to-lymphocyte ratio (NLR) and monocyte-to-lymphocyte ratio (MLR) were correlated with risk of death in patients with SE-CHB. NLR independently predicted progression to ACLF in patients without ACLF at enrolment and short-term mortality in ACLF patients. Plasma IL-6, IL-10, G-CSF and GM-CSF levels were higher in ACLF patients (P < .05). Blood transcriptome analyses showed that genes associated with cell migration and mobility and responses to wounding and bacteria were expressed at higher levels while genes involved in lymphocyte-mediated immunity were expressed at lower levels in HB-ACLF patients than in No-ACLF patients.

CONCLUSIONS

Systemic inflammation in HB-ACLF was characterized by an excessive innate immune response, which was associated with disease progression and mortality.

Quantitative assessment of HLA-DQ gene polymorphisms with the development of hepatitis B virus infection, clearance, liver cirrhosis, and hepatocellular carcinoma

Hepatitis B is one of the most common infectious diseases, which leads to public health problems in the world, especially in Asian counties. In recent years, extensive human genetic association studies have been carried out to identify susceptible genes and genetic polymorphisms to understand the genetic contributions to the disease progression of HBV infection. HLA-DQ gene variations have been reported to be associated with HBV infection/clearance, disease progression and the development of hepatitis B-related complications, including liver cirrhosis (LC) and hepatocellular carcinoma (HCC). However, the results are either inconclusive or controversial. Therefore, to derive a more precise estimation of the association, a meta-analysis was performed. Our data revealed that the HLA-DQ alleles rs2856718-G, rs7453920-A and rs9275319-G were significantly associated with decreased risk of HBV infection and HBV natural clearance. Logistic regression analyses showed that HLA-DQ alleles rs9275572-A significantly increased HBV infection clearance, and decreased HBV natural clearance. However, rs2856718-G and rs9275572-A were not associated with development of cirrhosis. The HLA-DQ polymorphisms (rs2856718 and rs9275572) were associated with a decreased HBV-related HCC risk in all genetic models, but rs9272105-A increased the risk of HBV-related HCC. In addition, no significant association was observed between HLA-DQ rs9275319-G polymorphism and HBV-related HCC. These stratified analyses were limited due to relatively modest size of correlational studies. In future, further investigation on a large population and different ethnicities are warranted. Our findings contribute to the personalized care and prognosis in hepatitis B.

Genetic susceptibility to infectious diseases: Current status and future perspectives from genome-wide approaches

Genome-wide association studies (GWASs) have been widely applied to identify genetic factors that affect complex diseases or traits. Presently, the GWAS Catalog includes > 2800 human studies. Of these, only a minority have investigated the susceptibility to infectious diseases or the response to therapies for the treatment or prevention of infections. Despite their limited application in the field, GWASs have provided valuable insights by pinpointing associations to both innate and adaptive immune response loci, as well as novel unexpected risk factors for infection susceptibility. Herein, we discuss some issues and caveats of GWASs for infectious diseases, we review the most recent findings ensuing from these studies, and we provide a brief summary of selected GWASs for infections in non-human mammals. We conclude that, although the general trend in the field of complex traits is to shift from GWAS to next-generation sequencing, important knowledge on infectious disease-related traits can be still gained by GWASs, especially for those conditions that have never been investigated using this approach. We suggest that future studies will benefit from the leveraging of information from the host's and pathogen's genomes, as well as from the exploration of models that incorporate heterogeneity across populations and phenotypes. Interactions within HLA genes or among HLA variants and polymorphisms located outside the major histocompatibility complex may also play an important role in shaping the susceptibility and response to invading pathogens.

•

Relatively few GWASs for infectious diseases were performed.

•

Phenotype heterogeneity and case/control misclassification can affect GWAS power.

•

Adaptive and innate immunity loci were identified in several infectious disease GWASs.

•

Unexpected loci (e.g., lncRNAs) were also associated with infection susceptibility.

•

GWASs should integrate host and pathogen diversity and use complex association models.