CLONAL STABILITY IN LATE-RELAPSING CHILDHOOD LYMPHOBLASTIC-LEUKEMIA

We report stability of a clonal immunoglobulin heavy chain (IgH) gene rearrangement in a case of childhood acute lymphoblastic leukaemia (AL L) relapsing 17 years after completion of first-line therapy. Clonal s tability was shown by polymerase chain reaction amplification of the h ypervariable CDRIII region of IgH gene. Identically sized products fro m the original diagnostic acid the second presentation samples were ob tained and direct sequencing confirmed complete sequence homology. Abs ence of clonal evolution together with recent reports of persistent mi nimal residual disease in patients in long-term complete remission, su ggests that 'cure' of childhood ALL may be critically dependent on eff ective immune surveillance to keep such disease below clinically signi ficant levels.