Genetic variants are identified to increase risk of COVID-19 related mortality from UK Biobank data

BACKGROUND

The severity of coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is highly heterogeneous. Studies have reported that males and some ethnic groups are at increased risk of death from COVID-19, which implies that individual risk of death might be influenced by host genetic factors.

METHODS

In this project, we consider the mortality as the trait of interest and perform a genome-wide association study (GWAS) of data for 1778 infected cases (445 deaths, 25.03%) distributed by the UK Biobank. Traditional GWAS fails to identify any genome-wide significant genetic variants from this dataset. To enhance the power of GWAS and account for possible multi-loci interactions, we adopt the concept of super variant for the detection of genetic factors. A discovery-validation procedure is used for verifying the potential associations.

RESULTS

We find 8 super variants that are consistently identified across multiple replications as susceptibility loci for COVID-19 mortality. The identified risk factors on chromosomes 2, 6, 7, 8, 10, 16, and 17 contain genetic variants and genes related to cilia dysfunctions (DNAH7 and CLUAP1), cardiovascular diseases (DES and SPEG), thromboembolic disease (STXBP5), mitochondrial dysfunctions (TOMM7), and innate immune system (WSB1). It is noteworthy that DNAH7 has been reported recently as the most downregulated gene after infecting human bronchial epithelial cells with SARS-CoV-2.

CONCLUSIONS

Eight genetic variants are identified to significantly increase the risk of COVID-19 mortality among the patients with white British ancestry. These findings may provide timely clues and potential directions for better understanding the molecular pathogenesis of COVID-19 and the genetic basis of heterogeneous susceptibility, with potential impact on new therapeutic options.

Role of bacterial and genetic factors in gastric cancer in Costa Rica

AIM: To evaluate several risk factors for gastric cancer (GC) in Costa Rican regions with contrasting GC incidence rate (GCIR).

METHODS: According to GCIR, 191 Helicobacter pylori (H pylori)-positive patients were classified into groups A (high GCIR, n = 101) and B (low GCIR, n = 90). Human DNA obtained from biopsy specimens was used in the determination of polymorphisms of the genes coding for interleukin (IL)-1&bgr; and IL-10 by PCR-RFLP, and IL-1RN by PCR. H pylori DNA extractions obtained from clinical isolates of 83 patients were used for PCR-based genotyping of H pylori cagA, vacA and babA2. Human DNA from gastric biopsies of 52 GC patients was utilized for comparative purposes.

RESULTS: Cytokine polymorphisms showed no association with GCIR variability. However, gastric atrophy, intestinal metaplasia and strains with different vacA genotypes in the same stomach (mixed strain infection) were more frequently found in group A than in group B, and cagA and vacA s1b were significantly associated with high GCIR (P = 0.026 and 0.041, respectively). IL-1&bgr;+3954_T/C (OR 2.1, 1.0-4.3), IL-1RN*2/L (OR 3.5, 1.7-7.3) and IL-10-592_C/A (OR 3.2, 1.5-6.8) were individually associated with GC, and a combination of these cytokine polymorphisms with H pylori vacA s1b and m1 further increased the risk (OR 7.2, 1.4-36.4).

CONCLUSION: Although a proinflammatory cytokine genetic profile showed an increased risk for developing GC, the characteristics of H pylori infection, in particular the status of cagA and vacA genotype distribution seemed to play a major role in GCIR variability in Costa Rica.

Causal role of Helicobacter pylori infection in gastric cancer

Gastric cancer is the second most frequent cancer in the world, accounting for a large proportion of all cancer cases in Asia, Latin America, and some countries in Europe. Helicobacter pylori (H pylori) is regarded as playing a specific role in the development of atrophic gastritis, which represents the most recognized pathway in multistep intestinal-type gastric carcinogenesis. Recent studies suggest that a combination of host genetic factors, bacterial virulence factors, and environmental and lifestyle factors determine the severity of gastric damage and the eventual clinical outcome of H pylori infection. The seminal discovery of H pylori as the leading cause of gastric cancer should lead to effective eradication strategies. Prevention of gastric cancer requires better screening strategies to identify candidates for eradication.

Genetic variants are identified to increase risk of COVID-19 related mortality from UK Biobank data

Background

The severity of coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is highly heterogenous. Studies have reported that males and some ethnic groups are at increased risk of death from COVID-19, which implies that individual risk of death might be influenced by host genetic factors.

Methods

In this project, we consider the mortality as the trait of interest and perform a genome-wide association study (GWAS) of data for 1,778 infected cases (445 deaths, 25.03%) distributed by the UK Biobank. Traditional GWAS failed to identify any genome-wide significant genetic variants from this dataset. To enhance the power of GWAS and account for possible multi-loci interactions, we adopt the concept of super-variant for the detection of genetic factors. A discovery-validation procedure is used for verifying the potential associations.

Results

We find 8 super-variants that are consistently identified across multiple replications as susceptibility loci for COVID-19 mortality. The identified risk factors on Chromosomes 2, 6, 7, 8, 10, 16, and 17 contain genetic variants and genes related to cilia dysfunctions (DNAH7 and CLUAP1), cardiovascular diseases (DES and SPEG), thromboembolic disease (STXBP5), mitochondrial dysfunctions (TOMM7), and innate immune system (WSB1). It is noteworthy that DNAH7 has been reported recently as the most downregulated gene after infecting human bronchial epithelial cells with SARS-CoV2.

Conclusions

Eight genetic variants are identified to significantly increase risk of COVID-19 mortality among the patients with white British ancestry. These findings may provide timely evidence and clues for better understanding the molecular pathogenesis of COVID-19 and genetic basis of heterogeneous susceptibility, with potential impact on new therapeutic options.

How genomics can be used to understand host susceptibility to enteric infection, aiding in the development of vaccines and immunotherapeutic interventions

Thanks to the modern sequencing era, the extent to which infectious disease imposes selective pressures on the worldwide human population is being revealed. This is aiding our understanding of the underlying immunological and host mechanistic defenses against these pathogens, as well as potentially assisting in the development of vaccines and therapeutics to control them. As a consequence, the workshop "How genomics can be used to understand host susceptibility to enteric infection, aiding in the development of vaccines and immunotherapeutic interventions" at the VASE 2018 meeting, aimed to discuss how genomics and related tools could be used to assist Shigella and ETEC vaccine development. The workshop featured four short presentations which highlighted how genomic applications can be used to assist in the identification of genetic patterns related to the virulence of disease, or host genetic factors that could contribute to immunity or successful vaccine responses. Following the presentations, there was an open debate with workshop attendees to discuss the best ways to utilise such genomic studies, to improve or accelerate the process of both Shigella and ETEC vaccine development. The workshop concluded by making specific recommendations on how genomic research methods could be strengthened and harmonised within the ETEC and Shigella research communities.

Genome-Wide Association Study Reveals Host Genetic Factors for Liver Diseases

A number of disease-associated genetic markers for common liver diseases have been identified using genome-wide association studies (GWASs). The GWAS strategy is based on genome-wide single-nucleotide polymorphism typing technologies, which are now commercially available, accompanied by statistical methods to identify host genetic factors that are associated with target diseases or complex genetic traits. One of the most striking features of the GWAS strategy is the ability to identify unexpected disease-associated genetic markers across the entire human genome. Here, we describe the technological aspects of the GWAS strategy with examples from actual GWAS reports related to hepatitis research, including drug response for patients with chronic hepatitis C, susceptibility to primary biliary cirrhosis, and hepatitis-B-related hepatocellular carcinoma.

Genome-wide association study identifies new loci associated with risk of HBV infection and disease progression

BACKGROUND

Recent studies have identified susceptibility genes of HBV clearance, chronic hepatitis B, liver cirrhosis, hepatocellular carcinoma, and showed the host genetic factors play an important role in these HBV-related outcomes.

METHODS

Collected samples from different outcomes of HBV infection and performed genotyping by Affymetrix 500 k SNP Array. GCTA tool, PLINK, and Bonferroni method were applied for analysis of genotyping and disease progression. ANOVA was used to evaluate the significance of the association between biomarkers and genotypes in healthy controls. PoMo, FST, Vcftools and Rehh package were used for building the racial tree and population analysis. FST statistics accesses 0.15 was used as a threshold to detect the signature of selection.

RESULTS

There are 1031 participants passed quality control from 1104 participants, including 275 HBV clearance, 92 asymptomatic persistence infection (ASPI), 93 chronic hepatitis B (CHB), 188 HBV-related decompensated cirrhosis (DC), 214 HBV-related hepatocellular carcinoma (HCC) and 169 healthy controls (HC). In the case-control study, one novel locus significantly associated with CHB (SNP: rs1264473, Gene: GRHL2, P = 1.57 × 10-6) and HCC (SNP: rs2833856, Gene: EVA1C, P = 1.62 × 10-6; SNP: rs4661093, Gene: ETV3, P = 2.26 × 10-6). In the trend study across progressive stages post HBV infection, one novel locus (SNP: rs1537862, Gene: LACE1, P = 1.85 × 10-6), and three MHC loci (HLA-DRB1, HLA-DPB1, HLA-DPA2) showed significant increased progressive risk from ASPI to CHB. Underlying the evolutionary study of HBV-related genes in public database, the derived allele of two HBV clearance related loci, rs3077 and rs9277542, are under strong selection in European population.

CONCLUSIONS

In this study, we identified several novel candidate genes associated with individual HBV infectious outcomes, progressive stages, and liver enzymes. Two SNPs that show selective significance (HLA-DPA1, HLA-DPB1) in non-East Asian (European, American, South Asian) versus East Asian, indicating that host genetic factors contribute to the ethnic disparities of susceptibility of HBV infection. Taken together, these findings provided a new insight into the role of host genetic factors in HBV related outcomes and progression.

Association of the C allele of rs479200 in the EGLN1 gene with COVID-19 severity in Indian population: a novel finding

The present study investigated two single nucleotide polymorphisms (SNPs)-rs479200 and rs516651 in the host EGLN1/PHD2 gene for their association with COVID-19 severity. A retrospective cohort of 158 COVID-19 patients from the Indian population (March 2020 to June 2021) was enrolled. Notably, the frequency of C allele (0.664) was twofold higher than T allele (0.336) in severe COVID-19 patients. Here, we report a novel finding that the C allele of rs479200 in the EGLN1 gene imparts a high risk of severe COVID-19 (odds ratio-6.214 (1.84-20.99) p = 0.003; 9.421 (2.019-43.957) p = 0.004), in additive inheritance model (adjusted and unadjusted, respectively).

IMPLICATION OF FIVE AIDS RELATED GENES IN MOTHER-TO-CHILD TRANSMISSION AND ACQUISITION OF HUMAN IMMUNODEFICIENCY VIRUS 1 IN CAMEROON

BACKGROUND

Genetic variants in the mother and/or infant have been described with evidence to be associated with mother-to-child transmission of HIV, but somehow with contradictory results depending on ethnic or geographic populations. We aimed at looking at the association between the allelic frequency of some genes with vertical transmission or acquisition of HIV in Cameroon.

METHODOLOGY

A total of 262 mothers (212 HIV-infected and 50 HIV non-infected) with their babies (270 in total, 42 HIV exposed-infected, 178 HIV exposed non-infected and 50 HIV non-exposed) were recruited in Yaounde-Cameroon. Their genotypes for CCR5-Delta32, CCR5 promoter59029A/G, CCR2-64I, SDF1-3'A and TRIM5α-136Q were analyzed using polymerase chain reaction and restriction fragment length polymorphisms.

RESULTS

Allelic frequencies were 14.7%, 41.9%, 9.5% and 14.7% for CCR2-64I, CCR5-59029-A/G, TRIM5α-136Q, SDF1-3'A respectively in the mothers and 18.8%, 35.9%, 11.3% and 20.5% in the babies. No delta 32 mutation in the CCR5 gene was found. The mutant genotype was most significantly frequent in the non-transmitter than in the transmitter (p= 0.005) for the SDF-1 3'A. SDF1-3'A [Odd ratio = 1.69; 95% confidence interval: 0.1158 to 0.7277); was associated to MTCT, P = 0.008.The homozygote mutants for the CCR5-59029-G were significantly higher in the infected than in the exposed uninfected babies (p=0.04). The mutations in the other genes were neither implicated in the acquisition nor in the transmission.

CONCLUSION

SDF1-3'A was associated to the reduction of MTCT. The CCR5-59029-A/G favored acquisition of HIV by babies. Our study showed that polymorphisms in chemokine ligand may be involved in MTCT.