The leukaemia-initiating cells used in this xenograft model were from an MLL-AF4 ALL cell line (SEM) and, although this cell line was derived from a 6-year-old patient, the findings are likely to be similar in infant leukaemia given the shared genetic basis and the fact that CNS involvement is a particularly prominent complication in infant patients. This evidence concerns the gene KMT2A and leukemia.