Non-productive or thalassemic-like heavy-chain gene rearrangement in a K-chain CLL clone

Information obtained from the study of immunoglobulin (Ig) gene rearrangement in different types of lymphoproliferative disorders has led to the suggestion that Ig gene activation obeys a precise hierarchy in which heavy-chain gene rearrangement procedes light-chain gene recombination. However no information is available on the mechanism(s) controlling this sequential activation. We report here a case of CLL which suggests that the expression of the heavy-chain genes is not necessary for light-chain gene rearrangement, or that very low amounts of heavy-chain mRNA and/or heavy chains are sufficient to activate k-chain genes.