Novel CBFB-MYH11 fusion in t(16;16) AML: PN 22. (A) Partial chimeric cDNA junctional sequence of 400-bp PCR product from PN 22. Sequencing was performed in both directions using primers C1 and M1. The new CBFB-MYH11 fusion site is shown by an asterisk at CBFB nt 455 and MYH11 nt 1893. The ORF is not disrupted by this fusion, but is 12 nt shorter than the type A fusion. (B) RT-PCR analysis confirming the presence of the new fusion type in PN 22 AML. PCR was performed using primers C1 and doM3′, followed by specific oligonucleotide hybridization (do probe), as described in the Materials and Methods. Lane 1, PCR amplification of reverse transcribed cDNA from PN 22 AML sample; lane 2, seminested PCR amplification from aliquot of first round C1-M1 PCR product of PN 22 sample; lane 3, AML-M4 sample lacking the inv(16)/t(16;16) andCBFB-MYH11 fusion by RT-PCR (this case not included in study group); lane 4, PN 11 sample with type A CBFB-MYH11 fusion by C1-M1 PCR; lane 5, negative control (noRNA).