HUMARA-PCR in CD33⁺ from patient no. 33 at 6 months after induction of MCR by imatinib.

HpaII indicates HpaII digestion of DNA. FISH of CD33⁺ WBCs failed but 77% of total WBCs carried t(20;21), whereas BCR-ABL was not detected. Note that the larger allele (arrow) is lacking from the HpaII-digested CD33⁺ cells but not from the CD3⁺ cells, consistent with a monoclonal CD33⁺ population.