Immunoglobulin kappa gene rearrangements between the kappa deleting element and J kappa recombination signal sequences in acute lymphoblastic leukemia and normal hematopoiesis

The kappa deleting element (kappa DE) located 24 kb downstream of the C kap pa gene segment mediates the deletion of C kappa and the J kappa-C kappa In tron enhancer, which results in allelic exclusion of the immunoglobulin kap pa light chain locus. We here report that the kappa DE can recombine to eac h recombination signal sequence (RSS) flanking J kappa 1 to J kappa 5 in no rmal hematopoiesis. Moreover, usage of the J kappa RSS-kappa DE junctional sequence allows the detection of minimal residual disease in acute lymphobl astic leukemia.