GWAS Identified IL4R and the Major Histocompatibility Complex Region as the Associated Loci of Total Serum IgE Levels in 9,260 Japanese Individuals

The genome-wide association study of serum IgE levels demonstrated a shared genetic background in allergic diseases

Immunoglobulin E (IgE) synthessis is highly related to a variety of atopic diseases, and several genome-wide association studies (GWASs) have demonstrated the association between genes and IgE level. In this study, we conducted the largest genome-wide association study of IgE involving a Taiwanese Han population. Eight independent variants exhibited genome-wide significance. Among them, an intronic SNP of CD28, rs1181388, and an intergenic SNP, rs1002957030, on 11q23.2 were identified as novel signals for IgE. Seven of the loci were replicated successfully in a meta-analysis using data on Japanese population. Among all the human leukocyte antigen (HLA) regions, HLA-DQA1*03:02 - HLA-DQB1*03:03 was the most significant haplotype (OR = 1.25, SE = 0.02, FDR = 1.6 × 10-14), corresponding to HLA-DQA1 Asp160 and HLA-DQB1 Leu87 amino acid residues. The genetic correlation showed significance between IgE and allergic diseases including asthma, atopic dermatitis, and pollinosis. IgE PRS was significantly correlated with total IgE levels. Furthermore, the top decile IgE polygenic risk score (PRS) group had the highest risk of asthma for the Taiwan Biobank and Biobank Japan cohorts. IgE PRS may be used to aid in predicting the occurrence of allergic reactions before symptoms occur and biomarkers are detectable. Our study provided a more comprehensive understanding of the impact of genomic variants, including complex HLA alleles, on serum IgE levels.

The origins and longevity of IgE responses as indicated by serological and cellular studies in mice and humans

The existence of long-lived IgE antibody-secreting cells (ASC) is contentious, with the maintenance of sensitization by the continuous differentiation of short-lived IgE+ ASC a possibility. Here, we review the epidemiological profile of IgE production, and give an overview of recent discoveries made on the mechanisms regulating IgE production from mouse models. Together, these data suggest that for most individuals, in most IgE-associated diseases, IgE+ ASC are largely short-lived cells. A subpopulation of IgE+ ASC in humans is likely to survive for tens of months, although due to autonomous IgE B cell receptor (BCR) signaling and antigen-driven IgE+ ASC apoptosis, in general IgE+ ASC probably do not persist for the decades that other ASC are inferred to do. We also report on recently identified memory B cell transcriptional subtypes that are the likely source of IgE in ongoing responses, highlighting the probable importance of IL-4Rα in their regulation. We suggest the field should look at dupilumab and other drugs that prohibit IgE+ ASC production as being effective treatments for IgE-mediated aspects of disease in most individuals.

Ehlers-Danlos syndrome type IV with a novel COL3A1 exon 14 skipping variation confirmed by Tohoku Medical Megabank Organization genomic database

A novel COL3A1 variant was identified in a Japanese case of Ehlers-Danlos syndrome type IV (EDS-IV) with a characteristic "Madonna" face, fragile uterus, and easy bruising in addition to a history of cavernous sinus fistula. We confirmed variable diameters of collagen fibrils in the dermis and decrease in type 3 collagen production from cultured fibroblasts. Genomic DNA sequencing of the COL3A1 region and COL3A1 cDNA sequence expressing in cultured fibroblasts identified that a nucleotide variation at c.951+2T>G on intron 14 leads to skipping of exon 14 in COL3A1 cDNA. The novel variation in the splice site of COL3A1 region g.IVS14+2T>G was not listed in the EDS-IV pathogenic genetic databases including Human Gene Mutation Database, ClinVar, and Leiden Open Variation Database. Using the whole genome sequence database of 8380 Japanese individuals reported by the Tohoku Medical Megabank Organization (ToMMo) cohort study, we also confirmed that COL3A1 g.IVS14+2T>G was not a common single nucleotide variation in the Japanese population, although 13 EDS-related COL3A1 variants were identified in the ToMMo database of 8380 Japanese individuals. These results demonstrated that our case of EDS-IV was a result of the novel variation of COL3A1 g.IVS14+2T>G. These statistical genetics approaches with the combination of the ToMMo database of 8380 Japanese individuals and pathogenic genetic databases are a useful method to confirm the uniqueness of novel variation in Japanese.