(A) Consequences of the t(11; 16). MLL on chromosome 11 and CBP on chromosome 16 are the genes involved in the t(11; 16) (q23; p13.3). The der(11) product contains 5′ MLL fused to 3′ CBP and the der(16) product contains 5′ CBP fused to 3′ MLL. BCR refers to the MLL breakpoint cluster region. (B) Cosmids and a PAC that span CBP were used for FISH analysis of patients with the t(11; 16). The arrows indicate the putative location of patient genomic breakpoints within CBP based on variability in FISH staining pattern using the CBP PAC.