This led to the identification of a BCR-ABL1-like phenotype in 15–50% of paediatric cases that harbour deletions in IKZF1, PAX5, EBF1, TCF3 and VPREB1. The BCR-ABL1-like group was then confirmed in 30–40% of adult B-ALL cases [254]. This evidence concerns the gene BCR and precursor B-cell acute lymphoblastic leukemia.