GWAS of Chronic Spontaneous Urticaria Reveals Genetic Overlap with Autoimmune Diseases, Not Atopic Diseases

Although chronic spontaneous urticaria (CSU) is a common disease, GWASs of CSU are lacking. We aimed to identify susceptibility SNPs by performing a GWAS in Chinese Han adults with CSU. The discovery cohort included 430 CSU cases and 482 healthy controls. The GWAS findings were validated in 800 CSU cases and 900 healthy controls. Genetic, functional enrichment, and bioinformatic analyses of genome-wide significant SNPs were performed to assess the association between CSU and autoimmunity or atopy. Five genome-wide significant SNPs were identified: rs434124/LILRA3, rs61986182/IGHG1/2, rs73075571/TDGF1, rs9378141/HLA-G, and rs3789612/PTPN22. The first four SNPs were in linkage disequilibrium with autoimmune-related diseases‒associated SNPs and were cis-expression quantitative trait loci in immune cells. The five SNPs-annotated genes were significantly enriched in immune processes. Higher polygenic risk scores and allele frequencies of rs3789612∗T, rs9378141∗C, and rs73075571∗G were significantly associated with autoimmune-related CSU phenotypes, including positive antithyroglobulin IgG, positive anti-FcεRIα IgG, total IgE40 IU/ml, and positive antithyroid peroxidase IgG but not with atopic or allergic sensitized CSU phenotypes. This GWAS of CSU identifies five risk loci and reveals that CSU shares genetic overlap with autoimmune diseases and that genetic factors predisposing to CSU mainly manifest through associations with autoimmune traits.