The genetic locus that harbors mutation(s) responsible for neurofibromatosis type 1 (NF1) is on chromosome 17, within band q11.2. We have mapped the human homologue of a murine gene (Evi-2) that is implicated in myeloid tumors, to a location between two NF1 translocation breakpoints on chromosome 17. Sequencing studies predict that EVI2 is a membrane protein that may complex with itself and/or other proteins within the membrane, perhaps to function as part of a cell-surface receptor. In the course of these studies we have also identified three other transcripts (classes of cDNAs) from the NF1 region. Two of them map between the NF1 translocation breakpoints; the remaining transcript maps just outside this region. The map location implicates these four genes as possible candidates for harboring NF1 mutations.