Endogenous retroviral sequence is fused to FGFR1 kinase in the 8p12 stem-cell myeloproliferative disorder with t(8;19)(p12;q13.3).

FGFR1, a transmembrane receptor tyrosine kinase for fibroblast growth factors, is constitutively activated by chromosomal translocations in an atypical stem-cell myeloproliferative disorder. The FGFR1 tyrosine domain is fused to dimerization domains encoded by 4 alternative genes: FOP at 6q27, CEP110 at 9q33, FIM/ZNF198 at 13q12, and BCR at 22q11. In this study, we report the molecular cloning of the t(8;19)(p12;q13.3), the fifth translocation associated with this syndrome. Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis and fluorescence in situ hybridization (FISH) demonstrated that the translocation resulted in a long terminal repeat of human endogenous retrovirus gene (HERV-K)/fibroblast growth factor receptor 1 (FGFR1) fusion transcript that incorporated 5' sequences from HERV-K fused in frame to 3' FGFR1 sequences encoding the kinase domain. RT-PCR detected only 1 of the 2 possible fusion transcripts, HERV-K/FGFR1.