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Background: Signal transducer and activator of transcription 6 (STAT6) is central to type 2 (T2) inflammation, and common noncoding variants at the STAT6 locus associate with various T2 inflammatory traits, including diseases, and its pathway is widely targeted in asthma treatment., Objective: We sought to test the association of a rare missense variant in STAT6, p.L406P, with T2 inflammatory traits, including the risk of asthma and allergic diseases, and to characterize its functional consequences in cell culture., Methods: The association of p.L406P with plasma protein levels, white blood cell counts, and the risk of asthma and allergic phenotypes was tested. Significant associations in other cohorts were also tested using a burden test. The effects of p.L406P on STAT6 protein function were examined in cell lines and by comparing CD4 + T-cell responses from carriers and noncarriers of the variant., Results: p.L406P associated with reduced plasma levels of STAT6 and IgE as well as with lower eosinophil and basophil counts in blood. It also protected against asthma, mostly driven by severe T2-high asthma. p.L406P led to lower IL-4-induced activation in luciferase reporter assays and lower levels of STAT6 in CD4 + T cells. We identified multiple genes with expression that was affected by the p.L406P genotype on IL-4 treatment of CD4 + T cells; the effect was consistent with a weaker IL-4 response in carriers than in noncarriers of p.L406P., Conclusions: A partial loss-of-function variant in STAT6 resulted in dampened IL-4 responses and protection from T2-high asthma, implicating STAT6 as an attractive therapeutic target., Competing Interests: Disclosure statement Disclosure of potential conflict of interest: K. Kristjansdottir, G. L. Norddahl, E. V. Ivarsdottir, G. H. Halldorsson, G. Einarsson, K. Bjarnadóttir, G. Rutsdottir, A. O. Arnthorsson, S. Gudmundsdottir, K. Gunnarsdottir, B. V. Halldorsson, H. Holm, S. Saevarsdottir, A. S. Snaebjarnarson, G. Sveinbjornsson, G. E. Thorlacius, G. Thorleifsson, V. Tragante, P. Sulem, D. F. Gudbjartsson, P. Melsted, I. Jonsdottir, T. A. Olafsdottir, and K. Stefansson are employees of deCODE genetics, a subsidiary of Amgen., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Immunoglobulin G (IgG) is the main isotype of antibody in human blood. IgG consists of four subclasses (IgG1 to IgG4), encoded by separate constant region genes within the Ig heavy chain locus (IGH). Here, we report a genome-wide association study on blood IgG subclass levels. Across 4334 adults and 4571 individuals under 18 years, we discover ten new and identify four known variants at five loci influencing IgG subclass levels. These variants also affect the risk of asthma, autoimmune diseases, and blood traits. Seven variants map to the IGH locus, three to the Fcγ receptor (FCGR) locus, and two to the human leukocyte antigen (HLA) region, affecting the levels of all IgG subclasses. The most significant associations are observed between the G1m (f), G2m(n) and G3m(b*) allotypes, and IgG1, IgG2 and IgG3, respectively. Additionally, we describe selective associations with IgG4 at 16p11.2 (ITGAX) and 17q21.1 (IKZF3, ZPBP2, GSDMB, ORMDL3). Interestingly, the latter coincides with a highly pleiotropic signal where the allele associated with lower IgG4 levels protects against childhood asthma but predisposes to inflammatory bowel disease. Our results provide insight into the regulation of antibody-mediated immunity that can potentially be useful in the development of antibody based therapeutics., (© 2024. The Author(s).)

Urticaria is a skin disorder characterized by outbreaks of raised pruritic wheals. In order to identify sequence variants associated with urticaria, we performed a meta-analysis of genome-wide association studies for urticaria with a total of 40,694 cases and 1,230,001 controls from Iceland, the UK, Finland, and Japan. We also performed transcriptome- and proteome-wide analyses in Iceland and the UK. We found nine sequence variants at nine loci associating with urticaria. The variants are at genes participating in type 2 immune responses and/or mast cell biology (CBLB, FCER1A, GCSAML, STAT6, TPSD1, ZFPM1), the innate immunity (C4), and NF-κB signaling. The most significant association was observed for the splice-donor variant rs56043070[A] (hg38: chr1:247556467) in GCSAML (MAF = 6.6%, OR = 1.24 (95%CI: 1.20-1.28), P-value = 3.6 × 10 -44 ). We assessed the effects of the variants on transcripts, and levels of proteins relevant to urticaria pathophysiology. Our results emphasize the role of type 2 immune response and mast cell activation in the pathogenesis of urticaria. Our findings may point to an IgE-independent urticaria pathway that could help address unmet clinical need., (© 2023. The Author(s).)