Detection and significance of bcr-abl mRNA transcripts and fusion proteins in Philadelphia-positive adult acute lymphoblastic leukemia.

Blast cells from an unselected consecutive series of 84 adults presenting with acute lymphoblastic leukemia (ALL) to St Bartholomew's Hospital over a seven year period were tested prospectively by cytogenetic and retrospectively by RT-PCR analysis for the presence of the Ph translocation and bcr-abl mRNA. This combination gave an overall figure of 20.3% for bcr-abl-positive and/or Ph-positive ALL. The incidence of bcr-abl-positive/Ph-positive ALL was most common between the ages of 31 and 50 years, becoming less common after the age of 50. Eight out of ten bcr-abl-positive patients expressed the e1a2 mRNA transcript, the other two expressed the b3a2 and b2a3 transcripts respectively. Cells from all patients with bcr-abl mRNA transcripts expressed the appropriate p190 or p210 bcr-abl protein and all were Ph-positive.