Nomenclature of the human immunoglobulin kappa (IGK) genes

'Nomenclature of the Human Immunoglobulin Kappa (IGK) Genes', the 17th report of the 'IMGT Locus in Focus' section, provides the first complete list of all the human IGK genes. In the most frequent haplotypes, the human IGK locus spans 1,820 kb and the IGKV genes are organized in two clusters separated by 800 kb. In those haplotypes where both the proximal and distal IGKV clusters are present, the total number of human IGK genes per haploid genome is 82 (107 genes if the orphons are included) of which 37-41 are functional. If only the proximal IGKV cluster is present, which is found in a rare haplotype, the total number of genes per haploid genome is 46 (71 genes if the orphons are included) of which 23-25 genes are functional. IMGT/HUGO gene names and definitions of the human IGK genes on chromosome 2p11.2, and IGK orphons on chromosomes 1, 2, 15, and 22 are provided with the gene functionality and the number of alleles according to the rules of the IMGT Scientific chart, with the accession numbers of the IMGT reference sequences, and the accession ID of the Genome Database GDB and NCBI LocusLink databases in which all the IMGT human IGK genes have been entered. The tables are available at the IMGT Marie-Paule page from IMGT, the international ImMunoGeneTics database (http://imgt.cines.fr:8104) created by Marie-Paule Lefranc, Université Montpellier II, CNRS, France.