Unraveling IGK locus in dog breeds: IMGT^® new insights into canine immunogenetics

Over thousands of years, selective breeding of domestic dogs (Canis lupus familiaris) has led to extensive genetic diversity, underscoring the need for refined genomic and immunogenetic investigations. This study presents a comprehensive analysis and biocuration of the immunoglobulin kappa light chain locus (IGK) across multiple dog breeds to identify breed-specific variations and assess their relevance to canine immunology and veterinary diagnostics. We examined nine canine genome assemblies to characterize structural variations, polymorphisms, and gene diversity, with the goal of enriching the IMGT^® reference database and expanding its representativeness across breeds. Through in-depth annotation of seven breeds-Bernese Mountain Dog, Boxer, Cairn Terrier, Labrador Retriever, Great Dane, Basenji, and German Shepherd-we identified 40 genes and 97 alleles, highlighting both conserved regions and unique breed-specific variants. Variants were validated in silico against Sanger sequencing data. Importantly, discrepancies were observed in the CanFam3.1 Boxer reference genome, indicating possible sequencing or assembly artifacts, challenges in gene and allele nomenclature standardization, and a low-density genomic segment within the IGK locus. These findings refine current knowledge of IGK locus diversity and enhance IMGT^® database accuracy, supporting future studies on immunogenetic variability, somatic hypermutation, and immune response mechanisms in canine health and disease.