Altered transcription of an oncogene in chronic myeloid leukaemia

The oncogene abl, which resides on chromosome 9, is translocated to chromosome 22 as part of the Philadelphia (Ph1) chromosome. Leukaemic cells from 5 of 6 patients with chronic myelogenous leukaemia (CML) and the Ph1 chromosome were found to contain a new 8 kb abl RNA transcript. This finding raises the possibility that the abl oncogene is directly involved in the development of CML. It is suggested that the abl gene's expression is altered by the DNA rearrangement in the translocation.