IGK (immunoglobulin kappa)
Atlas of Genetics and Cytogenetics in Oncology and Haematology
Identity HGNC (Hugo): IGK@ Location: 2p12 For complete Figure , see the international ImMunoGeneTics information system; Copyright 1995-2003 IMGT. Note The human IGK locus is located on chromosome 2 on the short arm, at band 2p12. The orientation of the locus has been determined by the analysis of translocations, involving the IGK locus, in leukemia and lymphoma. DNA/RNA Description The human IGK locus at 2p12 spans 1820 kb. It consists of 76 IGKV genes belonging to 7 subgroups, 5 IGKJ
... ps, 5 IGKJ segments, and a unique IGKC gene. The 76 IGKV genes are organized in two clusters separated by 800 kb. The IGKV distal cluster (the most 5' from IGKC and in the most centromeric position) spans 400 kb and comprises 36 genes. The IGKV proximal cluster (in 3' of the locus, closer to IGKC, and in the most telomeric position) spans 600 kb and comprises 40 genes. The potential genomic IGK repertoire comprises 31 to 35 functional IGKV genes belonging to 5 subgroups, the 5 IGKJ segments, and the unique IGKC gene. One rare IGKV haplotype has been described which contains only the proximal cluster. This haplotype comprises the 40 proximal IGKV genes belonging to 7 subgroups, of which 17 to 19 are functional and belong to 5 subgroups. Twenty-eight IGKV orphons have been identified and sequenced: 3 on the short arm of chromosome 2 but outside of the main IGK locus, 13 on the long arm of chromosome 2, 6 on chromosome 22, one on chromosome 1, one on chromosome 15, and 4 outside of chromosome 2. If both the proximal and distal IGKV clusters are present, the total number of human IGK genes per haploid genome is 82 (110 genes, if the orphons are included) of which 37-41 are functional. If only the proximal IGKV cluster is present, the total number of genes per haploid genome is 46 (74 genes, if the orphons are included) of which 23-25 genes are functional.