Persistent detection of a novel MLL–SACM1L rearrangement in the absence of leukemia

Most chromosomal rearrangements including the mixed lineage leukemia (MLL) gene are manifested as leukemia and predict a poor prognosis. Although more than 50 MLL-rearrangement partners are characterized, MLL-related leukemogenesis remains to be understood. Here we report a case of a 3-year old boy bearing a novel MLL-rearrangement with the suppressor of actin mutations 1-like (SACM1L) gene in the absence of leukemia. Bone marrow cells harboring the MLL–SACM1L rearrangement appeared during chemotherapy for acute lymphoblastic leukemia with hyperdiploidy and were continuously detected over 7 years without clonal expansion.