Brief report 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 utero at a time of developmentally regulated insertion of N regions into the DJH rearrangements of immunoglobulin heavy-chain (IgH) genes. Here it is shown that N regions are present in the clonotypic DJH rearrangements in 11 of 12 infant ALLs with t(4;11). These data are compared with the 122 previously published DJH 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. These findings, therefore, indicate that t(4;11)-positive infant ALL is initiated later in fetal development than most B-cell precursor ALL from children younger than 3 years and that they have a shorter latency period already in utero. (Blood. 2001;98:2272-2274)