T(6-8), T(8-9) AND T(8-13) TRANSLOCATIONS ASSOCIATED WITH STEM-CELL MYELOPROLIFERATIVE DISORDERS HAVE CLOSE OR IDENTICAL BREAKPOINTS IN CHROMOSOME REGION 8P11-12

A stem-cell myeloproliferative disorder involving T- and B-cell, and m yeloid lineages, is associated with three different translocations wit h a breakpoint in region p11-12 of chromosome 8: t(6;8)(q27;p11), t(8; 9)(p11;q33), and t(8;13)(p12;q12), respectively. Using fluorescence in situ hybridization (FISH), we have analysed blood cells from a series of five patients carrying these different translocations. We have ide ntified cosmids from chromosome region 8p11-12 that span the breakpoin t in all the cases. They are specific for the FGFR1 gene that encodes a receptor for members of the FGF family. The breakpoint was further d etected by Southern and pulsed-field gel electrophoresis analyses with probes from the FGFR1 locus.