NF1 and acute lymphoblastic leukemia: Near haploidy is present in ~2% of childhood ALL and is associated with Ras mutations (particularly NF1) and deletion/mutation of IKZF3. The gene expression profile and patterns of co-mutation (e.g., CREBBP and the Ras signaling pathway) are similar to high hyperdiploid ALL, suggesting a potential common origin of these two forms of leukemia.