2.2 Data source
Publicly available genome-wide association studies (GWAS) summaries were used in this study. Data for SNPs associated with the allergic disease was from the largest GWAS to date (meta-analysis of 13 studies), all of the European ancestry, including 180,129 cases with self-reported asthma and/or hay fever and/or eczema and 180,709 controls without any of these symptoms10. (Figure 2)
Genetic association estimates for hay fever, AR, or eczema diagnosed by the doctor (104,559 cases and 350,890 controls) and asthma diagnosed by the doctor (52,504 cases and 402,945 controls) were acquired from the UK Biobank (UKB), a population-based cohort study involving over half a million volunteers recruited in the United Kingdom (https://www.ukbiobank.ac.uk/)11. (Figure 3) Summary-level statistics for AR (5,527 cases and 212,387 controls), AD (7,024 cases and 198,740 controls), allergic asthma (4,859 cases and 135,449 controls), non-allergic asthma (3,155 cases and 184,148 controls), mixed asthma (724 cases and 135,448 controls) and childhood asthma (age<16 years) (3,025 cases and 135,449 controls) were retrieved from another large-scale biomedical European databases of FinnGen (https://www.finngen.fi/en), launched in 2017, unique in its integration of genomic information with digital medical data12. (Figure 3) The selection of GWAS summaries for each phenotype in this study followed the following principle: when no data for the phenotype was available in the UKB or no available IVs (the F statistics of SNPs were all <10) could be obtained from the UKB, GWAS data will be obtained from the FinnGen.
The latest and largest GWAS data sets for SARS‐CoV‐2 infection (159,840 cases and 2,782,977 controls) and severe respiratory confirmed COVID-19 (18,152 cases and 1,145,546 controls) were acquired from the COVID‐19 Host Genetics Initiative (HGI) GWAS meta‐analysis round 7 without the 23andMe cohort, released on 8 April 202213. Details of the cohorts included in this meta-analysis and the quality control were available athttps://www.covid19hg.org/results/r7/ . The population included was predominantly European.