Chronic myeloid leukemia with e14a3 BCR-ABL transcript: analysis of characteristics and prognostic significance

Chronic myeloid leukemia (CML) is characterized by Philadelphia chromosome (Ph) and BCR-ABL fusion genes. This study retrospectively analyzed 2381 CML patients with Ph chromosome confirmed by cytogenetics, Fluorescence in situ hybridization (FISH) or real-time quantitative polymerase chain reaction (Q-PCR). Among them, five CML patients without e13a2, e14a2 or e1a2 transcripts detected by Q-PCR were identified. DNA sequencing confirmed the fusion of BCR exon 14 and ABL exon 3. Case 1 reponded poorly to imatinib and achieved complete cytogenetic response (CCyR) after converting from imatinib to dasatinib. BCR-ABL transcripts were undetectable in cases after 2, 3 and 4 treated with imatinib after 6, 6 and 3 months, respectively, and in one patient who had undergone allogeneic hematopoietic stem cell transplantation after 4 months. Q-PCR may miss the detection of rare cases that are not covered by the primers used in Q-PCR, unless the proper primers are used.