ABL-BCR MESSENGER-RNAS TRANSCRIBED FROM CHROMOSOME-9Q-CHROMOSOME-POSITIVE CHRONIC MYELOID-LEUKEMIA( IN PHILADELPHIA)

Polymerase chain reaction amplification of reverse transcription produ cts has demonstrated the presence of abl-bcr hybrid mRNAs in RNA from peripheral blood leucocytes of Philadelphia-chromosome-positive chroni c myeloid leukaemia patients; such hybrid mRNAs can contain either of the alternative first exons of c-abl. A survey of 12 CMLs has shown th at abl-bcr mRNAs occur in the leucocytes of some, but not all, patient s, and that they are present both in chronic-phase and acute-phase leu cocytes.