BCR/ABL-negative chronic myeloid leukemia with ETV6/ABL fusion.

A BCR/ABL-negative chronic myeloid leukemia (CML) with t(12;14) (p12;q11-13) as the sole chromosomal abnormality was investigated by fluorescence in situ hybridization (FISH), which disclosed a cryptic insertion of ETV6 (previously called TEL), located at 12p12, into ABL at chromosome band 9q34. ETV6/ABL fusion was confirmed by RT-PCR, revealing that the first five exons of ETV6 were fused in frame with ABL at exon 2. Wild-type ETV6 was expressed, in accordance with the FISH results showing no deletion of the second ETV6 allele. ETV6/ABL chimeric transcripts have previously been reported in acute leukemias, but never before in CML. The present case suggests that ETV6/ABL positivity may constitute a new genetic subgroup of BCR-negative CML.