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 myeloid lineages, is associated with three different translocations with 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 identified cosmids from chromosome region 8p11-12 that span the breakpoint in all the cases. They are specific for the FCFR1 gene that encodes a receptor for members of the FGF family. The breakpoint was further detected by Southern and pulsed-field gel electrophoresis analyses with probes from the FGFR1 locus.