As recurrent chromosome abnormalities in leukemia are highly associate
d with particular subtypes, the genetic events of specific chromosome
alteration must be associated with leukemogenesis and characteristics
of the disease. The chromosomal breakpoints involved in inv(16) and t(
16;16) have been shown to generate the fusion gene PEBP2 beta(CBF beta
)/MYH11. The PEBP2 beta/MYH11 fusion transcripts in all 8 patients wit
h M4Eo, 2 of 18 with M4, and one CML in the blastic phase were detecte
d by using RT-PCR and Southern blotting. We demonstrated the marked ex
pression of CD34 and c-KIT (CD117) antigens in myelomonoblastic leukem
ia cells from all patients carrying this fusion gene, which was in con
trast to the patients with M4 but without the fusion gene. These resul
ts indicate that immunophenotypic analysis is useful for detection of
leukemia with the fusion gene, and that the PEBP2 beta/MYH11 fusion ge
ne is involved in immature cells expressing CD34 and c-KI'T antigens.