The first patient is a two-year-old girl with leukocytosis, circulating lymphoblasts, and a cryptic insertion of a short-arm segment at 10p12 into the long-arm segment of 11q23 resulting in an MLL and AF10 fusion transcript, which may be the first reported in <i>γδ</i> T-ALL. Here, MLLT10 is linked to acute lymphoblastic leukemia.