BAALC, the human member of a novel mammalian neuroectoderm gene lineage, is implicated in hematopoiesis and acute leukemia

The molecular basis of human leukemia is heterogeneous. Cytogenetic finding s are increasingly associated with molecular abnormalities, some of which a re being understood at the functional level. Specific therapies can be deve loped based on such knowledge. To search for new genes in the acute leukemi as, we performed a representational difference analysis. We describe a huma n gene in chromosome 8q22.3, BAALC (brain and acute leukemia, cytoplasmic), that is highly conserved among mammals but evidently absent from lower org anisms. We characterized BAALC on the genomic level and investigated its ex pression pattern in human and mouse, as well as its complex splicing behavi or. In vitro studies of the protein showing its subcellular localization su ggest a function in the cytoskeleton network. Two isoforms are specifically expressed in neuroectoderm-derived tissues, but not in tumors or cancer ce ll lines of nonneural tissue origin. We show that blasts from a subset of p atients with acute leukemia greatly overexpress eight different BAALC trans cripts, resulting in five protein isoforms. Among patients with acute myelo id leukemia, those overexpressing BAALC show distinctly poor prognosis, poi nting to a key role of the BAALC products in leukemia. Our data suggest tha t BAALC is a gene implicated in both neuroectodermal and hematopoietic cell functions.