Jesper Qvist Thomassen

Abstract Previous genome-wide association studies (GWASs) of stroke — the second leading cause of death worldwide — were conducted predominantly in populations of European ancestry 1,2 . Here, in cross-ancestry GWAS meta-analyses of 110,182 patients who have had a stroke (five ancestries, 33% non-European) and 1,503,898 control individuals, we identify association signals for stroke and its subtypes at 89 (61 new) independent loci: 60 in primary inverse-variance-weighted analyses and 29 in secondary meta-regression and multitrait analyses. On the basis of internal cross-ancestry validation and an independent follow-up in 89,084 additional cases of stroke (30% non-European) and 1,013,843 control individuals, 87% of the primary stroke risk loci and 60% of the secondary stroke risk loci were replicated ( P < 0.05). Effect sizes were highly correlated across ancestries. Cross-ancestry fine-mapping, in silico mutagenesis analysis 3 , and transcriptome-wide and proteome-wide association analyses revealed putative causal genes (such as SH3PXD2A and FURIN ) and variants (such as at GRK5 and NOS3 ). Using a three-pronged approach 4 , we provide genetic evidence for putative drug effects, highlighting F11, KLKB1, PROC, GP1BA, LAMC2 and VCAM1 as possible targets, with drugs already under investigation for stroke for F11 and PROC. A polygenic score integrating cross-ancestry and ancestry-specific stroke GWASs with vascular-risk factor GWASs (integrative polygenic scores) strongly predicted ischaemic stroke in populations of European, East Asian and African ancestry 5 . Stroke genetic risk scores were predictive of ischaemic stroke independent of clinical risk factors in 52,600 clinical-trial participants with cardiometabolic disease. Our results provide insights to inform biology, reveal potential drug targets and derive genetic risk prediction tools across ancestries.

BACKGROUND AND AIMS: Anti-inflammatory trials have shown considerable benefits for cardiovascular disease. High neutrophil counts, an easily accessible inflammation biomarker, are associated with atherosclerosis in experimental studies. This study aimed to investigate the associations between neutrophil counts and risk of nine cardiovascular endpoints using observational and genetic approaches. METHODS: Observational studies were conducted in the Copenhagen General Population Study (n = 101 730). Genetic studies were firstly performed using one-sample Mendelian randomization (MR) with individual-level data from the UK Biobank (n = 365 913); secondly, two-sample MR analyses were performed using summary-level data from the Blood Cell Consortium (n = 563 085). Outcomes included ischaemic heart disease, myocardial infarction, peripheral arterial disease, ischaemic cerebrovascular disease, ischaemic stroke, vascular-related dementia, vascular dementia, heart failure, and atrial fibrillation. RESULTS: Observational analyses showed associations between high neutrophil counts with high risks of all outcomes. In the UK Biobank, odds ratios (95% confidence intervals) per 1-SD higher genetically predicted neutrophil counts were 1.15 (1.08, 1.21) for ischaemic heart disease, 1.22 (1.12, 1.34) for myocardial infarction, and 1.19 (1.04, 1.36) for peripheral arterial disease; similar results were observed in men and women separately. In two-sample MR, corresponding estimates were 1.14 (1.05, 1.23) for ischaemic heart disease and 1.11 (1.02, 1.20) for myocardial infarction; multiple sensitivity analyses showed consistent results. No robust associations in two-sample MR analyses were found for other types of leucocytes. CONCLUSIONS: Observational and genetically determined high neutrophil counts were associated with atherosclerotic cardiovascular disease, supporting that high blood neutrophil counts is a causal risk factor for atherosclerotic cardiovascular disease.

Importance: An estimated 40% of dementia is potentially preventable by modifying 12 risk factors throughout the life course. However, robust evidence for most of these risk factors is lacking. Effective interventions should target risk factors in the causal pathway to dementia. Objective: To comprehensively disentangle potentially causal aspects of modifiable risk factors for Alzheimer disease (AD) to inspire new drug targeting and improved prevention. Design, Setting, and Participants: This genetic association study was conducted using 2-sample univariable and multivariable mendelian randomization. Independent genetic variants associated with modifiable risk factors were selected as instrumental variables from genomic consortia. Outcome data for AD were obtained from the European Alzheimer & Dementia Biobank (EADB), generated on August 31, 2021. Main analyses were conducted using the EADB clinically diagnosed end point data. All analyses were performed between April 12 and October 27, 2022. Exposures: Genetically determined modifiable risk factors. Main Outcomes and Measures: Odds ratios (ORs) and 95% CIs for AD were calculated per 1-unit change of genetically determined risk factors. Results: The EADB-diagnosed cohort included 39 106 participants with clinically diagnosed AD and 401 577 control participants without AD. The mean age ranged from 72 to 83 years for participants with AD and 51 to 80 years for control participants. Among participants with AD, 54% to 75% were female, and among control participants, 48% to 60% were female. Genetically determined high-density lipoprotein (HDL) cholesterol concentrations were associated with increased odds of AD (OR per 1-SD increase, 1.10 [95% CI, 1.05-1.16]). Genetically determined high systolic blood pressure was associated with increased risk of AD after adjusting for diastolic blood pressure (OR per 10-mm Hg increase, 1.22 [95% CI, 1.02-1.46]). In a second analysis to minimize bias due to sample overlap, the entire UK Biobank was excluded from the EADB consortium; odds for AD were similar for HDL cholesterol (OR per 1-SD unit increase, 1.08 [95% CI, 1.02-1.15]) and systolic blood pressure after adjusting for diastolic blood pressure (OR per 10-mm Hg increase, 1.23 [95% CI, 1.01-1.50]). Conclusions and Relevance: This genetic association study found novel genetic associations between high HDL cholesterol concentrations and high systolic blood pressure with higher risk of AD. These findings may inspire new drug targeting and improved prevention implementation.

Importance: The APOE ε2 and APOE ε4 alleles are the strongest protective and risk-increasing, respectively, genetic variants for late-onset Alzheimer disease (AD). However, the mechanisms linking APOE to AD-particularly the apoE protein's role in AD pathogenesis and how this is affected by APOE variants-remain poorly understood. Identifying missense variants in addition to APOE ε2 and APOE ε4 could provide critical new insights, but given the low frequency of additional missense variants, AD genetic cohorts have previously been too small to interrogate this question robustly. Objective: To determine whether rare missense variants on APOE are associated with AD risk. Design, Setting, and Participants: Association with case-control status was tested in a sequenced discovery sample (stage 1) and followed up in several microarray imputed cohorts as well as the UK Biobank whole-exome sequencing resource using a proxy-AD phenotype (stages 2 and 3). This study combined case-control, family-based, population-based, and longitudinal AD-related cohorts that recruited referred and volunteer participants. Stage 1 included 37 409 nonunique participants of European or admixed European ancestry, with 11 868 individuals with AD and 11 934 controls passing analysis inclusion criteria. In stages 2 and 3, 475 473 participants were considered across 8 cohorts, of which 84 513 individuals with AD and proxy-AD and 328 372 controls passed inclusion criteria. Selection criteria were cohort specific, and this study was performed a posteriori on individuals who were genotyped. Among the available genotypes, 76 195 were excluded. All data were retrieved between September 2015 and November 2021 and analyzed between April and November 2021. Main Outcomes and Measures: In primary analyses, the AD risk associated with each missense variant was estimated, as appropriate, with either linear mixed-model regression or logistic regression. In secondary analyses, associations were estimated with age at onset using linear mixed-model regression and risk of conversion to AD using competing-risk regression. Results: A total of 544 384 participants were analyzed in the primary case-control analysis; 312 476 (57.4%) were female, and the mean (SD; range) age was 64.9 (15.2; 40-110) years. Two missense variants were associated with a 2-fold to 3-fold decreased AD risk: APOE ε4 (R251G) (odds ratio, 0.44; 95% CI, 0.33-0.59; P = 4.7 × 10-8) and APOE ε3 (V236E) (odds ratio, 0.37; 95% CI, 0.25-0.56; P = 1.9 × 10-6). Additionally, the cumulative incidence of AD in carriers of these variants was found to grow more slowly with age compared with noncarriers. Conclusions and Relevance: In this genetic association study, a novel variant associated with AD was identified: R251G always coinherited with ε4 on the APOE gene, which mitigates the ε4-associated AD risk. The protective effect of the V236E variant, which is always coinherited with ε3 on the APOE gene, was also confirmed. The location of these variants confirms that the carboxyl-terminal portion of apoE plays an important role in AD pathogenesis. The large risk reductions reported here suggest that protein chemistry and functional assays of these variants should be pursued, as they have the potential to guide drug development targeting APOE.

AIMS: The association of plasma high-density lipoprotein (HDL) cholesterol with risk of dementia is unclear. We, therefore, tested the hypothesis that high levels of plasma HDL cholesterol are associated with increased risk of dementia and whether a potential association is of a causal nature. METHODS AND RESULTS: In two prospective population-based studies, the Copenhagen General Population Study and the Copenhagen City Heart Study (N = 111 984 individuals), we first tested whether high plasma HDL cholesterol is associated with increased risk of any dementia and its subtypes. These analyses in men and women separately were adjusted multifactorially for other risk factors including apolipoprotein E (APOE) genotype. Second, taking advantage of two-sample Mendelian randomization, we tested whether genetically elevated HDL cholesterol was causally associated with Alzheimer's disease using publicly available consortia data on 643 836 individuals. Observationally, multifactorially adjusted Cox regression restricted cubic spline models showed that both men and women with extreme high HDL cholesterol concentrations had increased risk of any dementia and of Alzheimer's disease. Men in the 96th-99th and 100th vs. the 41st-60th percentiles of HDL cholesterol had multifactorially including APOE genotype adjusted hazard ratios of 1.66 (95% confidence interval 1.30-2.11) and 2.00 (1.35-2.98) for any dementia and 1.59 (1.16-2.20) and 1.87 (1.11-3.16) for Alzheimer's disease. Corresponding estimates for women were 0.94 (0.74-1.18) and 1.45 (1.03-2.05) for any dementia and 0.94 (0.70-1.26) and 1.69 (1.13-2.53) for Alzheimer's disease. Genetically, the two-sample Mendelian randomization odds ratio for Alzheimer's disease per 1 SD increase in HDL cholesterol was 0.92 (0.74-1.10) in the IGAP2019 consortium and 0.98 (0.95-1.00) in the ADSP/IGAP/PGC-ALZ/UKB consortium. Similar estimates were observed in sex stratified analyses. CONCLUSION: High plasma HDL cholesterol was observationally associated with increased risk of any dementia and Alzheimer's disease, suggesting that HDL cholesterol can be used as an easily accessible plasma biomarker for individual risk assessment.