IDENTIFICATION OF A HUMAN LIM-HOX GENE, HLH-2, ABERRANTLY EXPRESSED IN CHRONIC MYELOGENOUS LEUKEMIA AND LOCATED ON 9Q33-34.1

We describe the isolation of human LH-2, a putative transcription fact or containing two cysteine-rich regions (LIM domains) and a homeobox ( Hox) DNA-binding domain. High levels of hLH-2 expression were observed in all cases of chronic myelogenous leukaemia (CML) tested, regardles s of disease status. hLH-2 was mapped to chromosome 9q33-34.1, in the same region as the reciprocal translocation that creates the BCR-ABL c himera of the Philadelphia chromosome (Ph'), the hallmark of CML; hLH- 2 was retained on the derivative 9 chromosome and is therefore centrom eric of c-ABL. The proximity of hLH-2 to the breakpoint on chromosome 9 raises the possibility of cis-activation by the t(9;22)(q34;q11) tra nslocation. In addition to finding hLH-2 expression in all cases of CM L, expression was observed in lymphoid malignancies and myeloid cell l ines, but not in primary cases of acute myelogenous leukaemia. The rol e of hLH-2 in the development or progression of leukaemia is not known . However, hLH-2 may prove useful as a marker of CML for monitoring re sidual disease.