Aberrant expression of the LHX4 LIM-homeobox gene caused by t(1;14)(q25;q32) in chronic myelogenous leukemia in biphenotypic blast crisis

Chromosomal aberrations observed in addition to the Philadelphia chromosome in chronic myelogenous leukemia (CML) are likely to be involved in disease progression to the blast crisis. We describe here a t(1;14)(q25;q32) as an additional chromosomal aberration in a patient with CML in biphenotypic blast crisis. By use of long-distance inverse polymerase chain reaction (PCR), we cloned the chromosomal breakpoint and revealed that the immunoglobulin heavy chain gene is fused near its Emu enhancer region to the 5' region of the LHX4 LIM-homeobox gene, whose expression is restricted to the central nervous system. By use of quantitative real-time reverse-transcription PCR, we found that the LHX4 mRNA is expressed at high levels in the patient's leukemic cells and in an acute lymphoblastic leukemia (ALL) cell line. The aberrant expression of the LHX4 gene by the t(1;14)(q25;q32) has very recently been reported in a case of ALL, thus, representing a rare, but recurrent genetic abnormality of possible importance in leukemogenesis. (C) 2003 Wiley-Liss, Inc.