Presence of N regions in the clonotypic DJ rearrangements of the immunoglobulin heavy-chain genes indicates an exquisitely short latency in t(4;11)-positive infant acute lymphoblastic leukemia

Childhood acute lymphoblastic leukemia (ALL) Is frequently initiated in ute ro at a time of developmentally regulated insertion of N regions into the D J(H) rearrangements of immunoglobulin heavy-chain (Ig(H)) genes. Here it is shown that N regions are present In the clonotypic DJ(H) rearrangements In 11 of 12 infant ALLs with t(4;11). These data are compared with the 122 pr eviously published DJ(H) sequences and were found to have a pattern similar to that of ALL in children older than 3 years at diagnosis but were unlike that in children younger than 3 years who predominantly lack N regions. Th ese findings, therefore, indicate that t(4;11)-positive infant ALL is initi ated later in fetal development than most B-cell precursor ALL from childre n younger than 3 years and that they have a shorter latency period already in utero. (C) 2001 by The American Society of Hematology.