Gene expression profiling in Ph⁺ ALL delineates 2 distinct groups that segregate cases with or without multilineage involvement, referred as multilineage or lymphoid clusters, respectively. These groups are associated with distinct genomic features including HBS1L deletion and monosomy 7 for the multilineage cluster and IKZF1 homozygous deletion and CDKN2A/PAX5 deletions for the lymphoid cluster. UMAP, uniform manifold approximation and projection.