ImmunogeneticsPub Date : 2026-09-09DOI: 10.1007/s00251-026-01413-2
Agniya M Sokolova, Jacob Douek, Baruch Rinkevich
{"title":"Intra-colony divergence and global allele sharing reflect purifying selection and recombination at the Botryllus histocompatibility factor locus.","authors":"Agniya M Sokolova, Jacob Douek, Baruch Rinkevich","doi":"10.1007/s00251-026-01413-2","DOIUrl":"10.1007/s00251-026-01413-2","url":null,"abstract":"<p><p>Urochordates, the closest relatives of vertebrates, lack adaptive immunity. However, some taxa, such as the colonial species Botryllus schlosseri, provide a unique model for studying innate self/non-self recognition through natural allogeneic transplantation responses. In this species, interactions between colonies are controlled by a highly polymorphic locus, with the Botryllus histocompatibility factor (BHF) being the only gene known to predict tissue fusion or rejection outcomes with complete accuracy. Here, we analyzed full-length BHF alleles from 19 laboratory-born and wild colonies and found that highly divergent alleles tend to coexist within individuals, whereas identical alleles can be shared across continental-scale distances. Despite extensive length variation, evidence of intragenic recombination, and pronounced nucleotide diversity, BHF exhibits limited protein divergence, with 33 alleles encoding only 17 distinct protein variants. Contrary to expectations for polymorphic recognition genes, no evidence of balancing or directional selection was detected. Instead, signatures of purifying selection were observed. We propose that this contrast between nucleotide and protein diversity arises from the combined effects of recombination, human-mediated gene flow, and linkage to nearby loci under balancing selection, while functional constraints maintain protein stability. These findings suggest that extensive protein diversification may not be a universal driver of allorecognition gene evolution.</p>","PeriodicalId":13446,"journal":{"name":"Immunogenetics","volume":"78 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148911884","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
ImmunogeneticsPub Date : 2026-08-27DOI: 10.1007/s00251-026-01412-3
Aengus Officer, Ida Lindeman, Milena Pavlovic, Christin Lund-Andersen, Eivind Ness-Jensen, Geir Kjetil Sandve, Ludvig M Sollid
{"title":"Naïve adaptive immune receptor repertoires in celiac disease assessed by machine learning; impact of the HLA-DQ2.5 allotype on the TCR repertoire.","authors":"Aengus Officer, Ida Lindeman, Milena Pavlovic, Christin Lund-Andersen, Eivind Ness-Jensen, Geir Kjetil Sandve, Ludvig M Sollid","doi":"10.1007/s00251-026-01412-3","DOIUrl":"10.1007/s00251-026-01412-3","url":null,"abstract":"<p><p>The adaptive immune receptor repertoire (AIRR) - the collection of an individual's B-cell and T-cell receptors (BCRs and TCRs, respectively) - encodes cumulative immune history and is shaped by both germline genetics and environmental exposures. Skewed repertoires have been linked to infections, vaccination responses and autoimmune diseases such as celiac disease (CeD) where biased usage of immunoglobulin and T-cell receptor genes reactive to disease relevant antigens has been reported. Motivated by evidence that germline variation, notably human leukocyte antigen (HLA), influences naïve AIRRs and by prior machine-learning studies that classified CeD using naïve BCR AIRR-sequencing (AIRR-seq) data, we applied machine learning analysis to naïve CD4<sup>+</sup> TCR and naïve BCR AIRR-seq repertoires to test whether repertoire features can distinguish subjects with CeD from controls and to identify drivers of such classification. Naïve CD4<sup>+</sup> TCR repertoires yielded moderate diagnosis classification, but this signal was largely explained by enrichment of the HLA-DQ2.5 allotype. TCR variable gene frequencies predicted HLA-DQ2.5 status with high accuracy and controlling for HLA-DQ2.5 abolished TCR-based diagnosis classification. In contrast, naïve BCR repertoires could not be used to classify CeD. Overall, our findings show that germline HLA variation significantly affects naïve TCR composition and thereby indirectly facilitates moderately successful CeD status classification.</p>","PeriodicalId":13446,"journal":{"name":"Immunogenetics","volume":"78 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13518406/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148827976","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
ImmunogeneticsPub Date : 2026-07-28DOI: 10.1007/s00251-026-01409-y
Mohammad Y Alshahrani, Zahraa AlKhafaje, Uday Abdul-Reda Hussein, Zahraa Adel, Ola Kamal A Alkadir, Ahmed Aldulaimi, Rafid Kamal Jameel, Rafid Jihad Albadr, Mariem Alwan, Aseel Smerat
{"title":"Genetic association of immunosenescence to immune decline.","authors":"Mohammad Y Alshahrani, Zahraa AlKhafaje, Uday Abdul-Reda Hussein, Zahraa Adel, Ola Kamal A Alkadir, Ahmed Aldulaimi, Rafid Kamal Jameel, Rafid Jihad Albadr, Mariem Alwan, Aseel Smerat","doi":"10.1007/s00251-026-01409-y","DOIUrl":"10.1007/s00251-026-01409-y","url":null,"abstract":"<p><p>Immunosenescence is a complex biological process characterized by progressive remodeling of immune function during aging, leading to increased susceptibility to infections, chronic inflammatory diseases, cancer, and reduced vaccine efficacy. While cumulative antigen exposure, infections, lifestyle factors, environmental exposures, and epigenetic influences contribute to immune decline, a growing body of evidence suggests that genetic predisposition also plays an important modulatory role in shaping the molecular trajectory of immune aging. This review discusses how inherited variation in cytokine-regulatory pathways may influence IL-6, TNF-α, interferon, and TGF-β signaling, thereby contributing to inflammatory set points that favor chronic immune activation and inflammaging. Inherited differences in innate and adaptive immune signaling, including KIR-HLA interactions, DNA-sensing pathways, and downstream JAK-STAT and NF-κB cascades, may alter activation thresholds and immune-cell differentiation. Variants affecting mitochondrial redox balance and autophagy may enhance reactive oxygen species accumulation and metabolic exhaustion, thereby potentially contributing to immune-cell senescence. Genetic factors affecting folate metabolism, epigenetics, telomeres, and DNA repair drive epigenetic drift, cellular aging, and clonal instability in immune cells. These mechanisms appear as measurable molecular and cellular biomarkers, including inflammatory signals, immune cell activation, oxidative stress, telomere shortening, and multi-omic indicators. Understanding this molecular architecture provides a foundation for identifying predictive biomarkers and developing precision strategies to preserve immune competence and promote healthy aging.</p>","PeriodicalId":13446,"journal":{"name":"Immunogenetics","volume":"78 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148602464","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
ImmunogeneticsPub Date : 2026-07-13DOI: 10.1007/s00251-026-01411-4
Mingbin Xie, Yuanhong Wu, Xinyao Jin, Fengchun Jiang, Qiang Yao
{"title":"Causal relationship and pathogenic mechanism analysis of breast cancer and coronary heart disease based on mendelian randomization and transcriptome data analysis.","authors":"Mingbin Xie, Yuanhong Wu, Xinyao Jin, Fengchun Jiang, Qiang Yao","doi":"10.1007/s00251-026-01411-4","DOIUrl":"10.1007/s00251-026-01411-4","url":null,"abstract":"<p><p>Breast cancer (BC) is closely linked to coronary heart disease (CHD), yet the genetic causal relationship and common driving mechanism between the two have not been fully elucidated. The purpose of this study is to infer the causal relationship between BC and CHD at the genetic level and identify the cross-omic molecular characteristics of them through the integrated analysis of multiple genomics. Firstly, large-scale Genome Wide Association Study (GWAS) data were used for bidirectional Mendelian randomization (MR) analysis. Secondly, multi-center transcriptome data were integrated and combined with differential expression analysis (DEGs) and weighted gene co-expression network analysis (WGCNA) to screen for key comorbidity genes. Univariate, Least Absolute Shrinkage and Selection Operator (LASSO), and multivariate Cox regression analyses were used to construct a prognostic model. The Benjamin Hochberg method was used for False Discovery Rate (FDR) correction. Finally, molecular pathways were explored through Gene Set Enrichment Analysis (GSEA), and key genes were validated using quantitative real-time polymerase chain reaction (qRT-PCR) in independent clinical samples. MR analysis revealed a significant positive correlation between BC and CHD in Asian populations (OR = 1.095, 95% CI: 1.005-1.192, P = 0.037). However, no significant association was observed in European populations. Transcriptome analysis identified a prognostic risk score composed of 5 CHD-related genes (HES1, MLPH, TRIB3, HSPBP1, and STARD3), which can independently predict the prognosis of BC patients. GSEA analysis indicated that the comorbidity mechanism involved dysregulation of cell cycle, immune inflammation, and metabolism-related pathways. qRT-PCR verification confirmed that compared with patients with BC, the expression levels of HES1, TRIB3, HSPBP1, and STARD3 in the peripheral blood of BC combined with CHD patients were significantly upregulated (P < 0.05). This study established for the first time the genetic causal relationship between BC and CHD in Asian populations, and revealed the inflammation-immune-metabolism molecular axis mediating comorbidities. The identified key genes not only serve as biomarkers for BC prognosis, but also provide a new perspective for understanding the pathological mechanisms and precise diagnosis and treatment of tumor cardiovascular comorbidities.</p>","PeriodicalId":13446,"journal":{"name":"Immunogenetics","volume":"78 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148430205","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
ImmunogeneticsPub Date : 2026-07-06DOI: 10.1007/s00251-026-01410-5
Alishba Kainat, Fazlul Aziz Mian, Muhammad Asif Nawaz Khan, Mubeen Tabish Nasim, Syed Muhammad Nurulain, Nazia Bibi, Syed Tahir Abbas Shah, Muhammad Jadoon Khan, Sabir Hussain
{"title":"Elevated interleukin-36γ and gene polymorphisms implicate novel risk in essential hypertension.","authors":"Alishba Kainat, Fazlul Aziz Mian, Muhammad Asif Nawaz Khan, Mubeen Tabish Nasim, Syed Muhammad Nurulain, Nazia Bibi, Syed Tahir Abbas Shah, Muhammad Jadoon Khan, Sabir Hussain","doi":"10.1007/s00251-026-01410-5","DOIUrl":"10.1007/s00251-026-01410-5","url":null,"abstract":"<p><p>Cytokines are crucial in regulating hypertension and vascular inflammation. The clinical significance of circulating IL-36γ levels and IL36G gene variants in relation to essential hypertension risk was assessed because IL-36γ has been associated with several cardiovascular diseases, while its role in essential hypertension is still unknown. Serum IL-36γ levels were determined by enzyme-linked immunosorbent assay, while IL36G polymorphisms were assessed by PCR-RFLP method in 264 patients with essential hypertension and 264 normotensive controls. Patients showed significantly elevated serum IL-36γ levels (p < 0.0001) when compared with the controls. Significant association between IL36G rs11690399 and rs11683399 polymorphisms and essential hypertension susceptibility were found through genotyping analysis, with combination genotypes (GT + TT) and (TG + GG) conferring an elevated risk of a disease. A 2.6-fold and a 1.9-fold increased risk of essential hypertension was observed to the T allele of rs11690399 and the G allele of rs11683399, respectively. Significantly higher levels of IL-36γ were associated with variant genotypes, suggesting a genotype-phenotype correlation. T-T and T-G were found to be a risk haplotype for essential hypertension by haplotype analysis. A causal relationship between increased IL-36γ and the risk of hypertension was shown by Mendelian randomization (OR = 1.0066; 95% CI: 1.0028-1.0104, p < 0.0001). A diagnostic performance for IL-36γ (AUC = 0.862) was found by ROC analysis, indicating its potential as a clinical biomarker. In conclusion, there is a significant association between essential hypertension and higher IL-36γ levels and IL36G polymorphisms. These results suggest that elevated circulatory IL-36γ may play a role in the pathophysiology of essential hypertension.</p>","PeriodicalId":13446,"journal":{"name":"Immunogenetics","volume":"78 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148390781","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
ImmunogeneticsPub Date : 2026-07-06DOI: 10.1007/s00251-026-01407-0
Esra Çolak Geniş, Fethi Sırrı Çam
{"title":"Genotype-phenotype correlations in autoimmune and autoinflammatory diseases: An NGS-based immunogenetic cohort study.","authors":"Esra Çolak Geniş, Fethi Sırrı Çam","doi":"10.1007/s00251-026-01407-0","DOIUrl":"10.1007/s00251-026-01407-0","url":null,"abstract":"<p><p>ObjectiveAutoimmune and autoinflammatory diseases (AIDs) represent a heterogeneous group of immune-mediated disorders characterized by dysregulated innate and adaptive immune responses. This study aimed to investigate the immunogenetic background of AIDS by assessing the distribution of genetic variants identified by a targeted next-generation sequencing (NGS) panel and elucidating genotype-phenotype correlations in the context of systemic immune dysregulation.Materials and methodsA targeted NGS panel encompassing 19 genes involved in immune regulation, inflammatory signaling pathways, and immune tolerance was utilized to evaluate a cohort of 110 patients presenting with clinical manifestations suggestive of autoinflammatory disease. Clinical severity was quantitatively assessed using longitudinal serum C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) measurements across acute and baseline periods. Detected variants were classified according to the American College of Medical Genetics and Genomics (ACMG) guidelines and correlated with patient clinical phenotypes and established immunogenetic literature.ResultsA total of 55 genetic variants were identified across 41 patients. Alterations predominantly clustered in MEFV (38.2%), HFE (29.1%), and SLC29A3 (21.8%), followed by NOD2, MVK, CARD14, IL10RB, and PLCG2 (1.8% each). According to ACMG criteria, 61.8% of the variants were pathogenic, 25.5% were likely pathogenic, and 12.7% were VUS. Genotype-phenotype correlation analyses successfully linked rare variants (including PLCG2, IL10RB, and CARD14) and oligogenic combinations to specific laboratory profiles. These findings revealed unexpected penetrance, variable expressivity, and distinct biomarker disassociations, most notably highlighted by isolated ESR elevations reaching 91 mm/h.ConclusionOur findings underscore the immunogenetic heterogeneity of autoinflammatory diseases and substantiate the diagnostic value of NGS-based profiling in deciphering complex genotype-phenotype associations. The integration of specific quantitative biomarkers and downstream mechanisms highlights how non-HLA regulatory variants reshape the chronic inflammatory immune microenvironment, lowering the threshold for inflammasome activation and systemic autoimmunity.</p>","PeriodicalId":13446,"journal":{"name":"Immunogenetics","volume":"78 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148390748","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
ImmunogeneticsPub Date : 2026-07-04DOI: 10.1007/s00251-026-01408-z
Sonam Yadav, Chanchal Rana, Fanny Josan, Mir Ahmad Habib, Aditya Patel, Vikrant Gaur, Rakesh Kumar
{"title":"Unraveling the genomic structures, conserved functional domains and evolutionary dynamics of beta-defensins in Bubalus bubalis and Ovis aries.","authors":"Sonam Yadav, Chanchal Rana, Fanny Josan, Mir Ahmad Habib, Aditya Patel, Vikrant Gaur, Rakesh Kumar","doi":"10.1007/s00251-026-01408-z","DOIUrl":"10.1007/s00251-026-01408-z","url":null,"abstract":"<p><p>Defensins are key innate immune proteins exhibiting pleiotropic functions such as antibacterial activity, antiviral activity, anti-inflammatory activity, immunomodulatory functions, and roles in reproduction. Genomic information inadequately explains the whole gamut of the landscape of β-defensin in Bubalus bubalis and Ovis aries genomes. This study investigates the sequence evaluation and evolutionary relationships of β-defensin with 131 complete sequences in buffalo, sheep, and human. Sequence and domain-based analyses revealed diverse patterns of disulfide bridges and multiple signature patterns, including N- and O-glycosylation sites, N-myristoylation sites, and protein kinase C phosphorylation sites, indicating extensive post-translational regulation involved in various antimicrobial activities, signaling pathways, and reproduction. Phyre2-based 3D structural modeling, followed by PyMOL visualization, revealed β-strands stabilized by cysteine disulfide bonds and a short N-terminal α-helix. Variation analysis of β-defensin sequences identified unique allelic variants with several conserved amino acid positions. All sequences shared the characteristic six conserved cysteine residues, along with conserved glycine (G) in the GXC motif and glutamic acid (E), which contribute to structural stability and proper protein folding. We report sixteen amino acid sites depicting 9 distinct types of mutations within the cysteine residues, with most frequent substitutions of C→S (5/16) and C→P (3/16) amino acids. Phylogenetic and domain-based analyses across humans, sheep, and buffalo revealed eight major clusters, of which cluster I was found to be most diverse (36/131). Altogether, we provide a comprehensive analysis of β-defensin protein sequences revealing conserved features, functional motifs, and evolutionary relationships underpinning the functional role of β-defensins.</p>","PeriodicalId":13446,"journal":{"name":"Immunogenetics","volume":"78 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148382016","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
ImmunogeneticsPub Date : 2026-06-27DOI: 10.1007/s00251-026-01406-1
Roshani Fernando, Trisha Nicole Agulto, Eunjin Cho, Jaewon Kim, Andy van Hateren, Minjun Kim, Prabuddha Manjula, Jun Heon Lee
{"title":"Genetic characterization of the TAPBP and its allelic association with BF2 in the chicken major histocompatibility complex.","authors":"Roshani Fernando, Trisha Nicole Agulto, Eunjin Cho, Jaewon Kim, Andy van Hateren, Minjun Kim, Prabuddha Manjula, Jun Heon Lee","doi":"10.1007/s00251-026-01406-1","DOIUrl":"10.1007/s00251-026-01406-1","url":null,"abstract":"<p><p>TAPBP is a key chaperone of the peptide-loading complex that facilitates peptide loading onto major histocompatibility complex class I (MHC I) molecules. This study characterized TAPBP alleles in Korean Native Chickens (KNCs), identified novel variants, and evaluated allelic associations with BF2. Thirty-six samples representing six KNC lines were genotyped using LEI0258 and the MHC-B SNP panel, and individuals homozygous at both markers were classified into 16 groups. The same samples were subjected to Sanger sequencing of TAPBP exons 3-8. Sequences were assembled and aligned against MHC-B reference alleles of the TAPBP gene and the Red Junglefowl reference. Additional comparisons with \"tapasin allele\" datasets enabled the identification of novel variants. Six novel nucleotide variants were detected across exons 3-6, including one nonsynonymous substitution in exon 4 (D251H). This residue corresponds to position Q265 in human TAPBP and lies adjacent to residues involved in MHC I interaction, suggesting potential functional relevance. Furthermore, TAPBP exhibited high haplotype diversity (Hd = 0.93) and moderate nucleotide diversity (π = 0.00892), with exon 5 showing the highest diversity (π = 0.01). B9 was the most frequent allele at the nucleotide level, whereas B6/B24 predominated at the amino acid level. Comparison with BF2 data revealed allele-dependent pairing patterns: BF2-B9 consistently matched TAPBP-B9, whereas BF2-B6 was associated with distinct TAPBP nucleotide variants, indicating allelic diversification. Homozygosity at LEI0258 and the SNP panel corresponded with TAPBP homozygosity, supporting marker-based prediction. These findings highlight potential BF2-TAPBP associations and provide a foundation for understanding variation in MHC I peptide loading.</p>","PeriodicalId":13446,"journal":{"name":"Immunogenetics","volume":"78 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148338460","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
ImmunogeneticsPub Date : 2026-06-19DOI: 10.1007/s00251-026-01404-3
Francisco Gambón-Deza
{"title":"Reconstructed amphibian heavy-chain constant regions support a mosaic origin of IgXA with IgY-like CH1-CH2, an intermediate CH3, and an IgM-like CH4.","authors":"Francisco Gambón-Deza","doi":"10.1007/s00251-026-01404-3","DOIUrl":"10.1007/s00251-026-01404-3","url":null,"abstract":"<p><p>The evolutionary relationship between amphibian IgM, IgY, and IgX/A-like antibodies has remained difficult to resolve, largely because repetitive heavy-chain loci are often incompletely or inconsistently annotated. In this study, I re-analyzed reconstructed four-domain heavy-chain constant regions from amphibian loci to test whether the evolution of IgXA is better explained by uniform divergence or by a mosaic history involving partial exon replacement. The reconstructed dataset comprised 86 complete antibodies from 29 species (29 IgM, 33 IgY, and 24 IgXA). Exact nucleotide matching against the reconstructed exon set yielded 79 antibodies, allowing the identification of 21 strictly microsyntenic species-level IgM/IgY/IgXA trios for recombination analyses. Domain alignments, Poisson-corrected amino-acid distances, and UMAP embeddings revealed a clear structural transition: IgXA clustered closer to IgY in CH1 and CH2, remained nearly intermediate in CH3, and shifted decisively toward IgM in CH4. Mean inter-class distances (IgY-IgXA vs. IgM-IgXA) reflected this pattern: 0.964 vs. 1.275 in CH1, 1.254 vs. 1.477 in CH2, 1.242 vs. 1.248 in CH3, and 1.220 vs. 0.962 in CH4. Within-species trio comparisons reinforced this polarity: 16 of 21 trios displayed an IgY-like CH1-CH2, 16 exhibited an IgM-like CH4, and 12 combined both features. Furthermore, GARD detected recombination breakpoints close to the CH3/CH4 boundary in 6 of the 21 trios, including three cases within 30 nucleotides of the exon junction. Maximum-likelihood domain trees confirmed that the strongest IgXA-IgM sister relationship occurred in CH4, where the largest relevant clade showed 91.7/89.0 SH-aLRT/UFBoot support. Together, these reconstructed sequence data support a mosaic origin for amphibian IgXA, most parsimoniously explained by partial exon shuffling or replacement within a conserved constant-region genomic block.</p>","PeriodicalId":13446,"journal":{"name":"Immunogenetics","volume":"78 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148277291","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Climate factors and selection shape MHC class II diversity in a montane wild sheep (Ovis ammon).","authors":"Zi-Yue Tian, Jin-Yi Li, Zhen-Yuan Cai, Shamshidin Abduriyim","doi":"10.1007/s00251-026-01405-2","DOIUrl":"10.1007/s00251-026-01405-2","url":null,"abstract":"<p><p>Understanding how environmental heterogeneity drives spatially varying selection is key to deciphering adaptive evolution. The Major Histocompatibility Complex (MHC) provides an ideal model to study this process. We investigated the MHC class II DQA gene across seven subspecies of wild argali sheep (Ovis ammon) in China. High-throughput sequencing of 98 individuals revealed high diversity (25 alleles), with balancing selection maintaining allelic richness and trans-species polymorphism indicating long-term balancing selection. Molecular evolutionary analyses uncovered heterogeneous positive selection on antigen-binding sites among subspecies (ω = 1.181-3.000), mirroring variable pathogen-driven pressures. Mantel tests detected no significant isolation-by-distance or isolation-by-environment. However, Spearman correlations identified significant associations between specific alleles (e.g., Ovam-DQA*08) and climatic variables, as well as between allele frequencies and MaxEnt-predicted suitability. Redundancy analysis showed that temperature and precipitation explained 54.7% of allele frequency variance. Ecological niche modeling suggested that annual mean temperature was associated with allele distribution, indicating that abiotic factors may shape immunogenetic variation, likely by structuring pathogen communities. Our study provides the first MHC characterization in argali and elucidates how balancing and positive selection interact to maintain functional diversity, offering a foundation for predicting evolutionary responses to environmental change.</p>","PeriodicalId":13446,"journal":{"name":"Immunogenetics","volume":"78 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148271307","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}