MLL gene rearrangements identify a subgroup of acute leukemias with a bad p
rognosis. Fifty-one adult patients with de novo AML were screened for MLL r
earrangements by Southern blot. An unexpected high frequency of AML-MZ acco
rding to the FAB classification was found. The most striking morphologic fe
atures of these cases were the scarcity of Auer rods and granulocytic dyspl
asia. Morphologic traits could be helpful in distinguishing molecular group
s of AML-M2. (C) 1999 Elsevier Science Ltd. All rights reserved.