Mixed-lineage leukemia with t(10;11)(p13;q21): An analysis of AF10-CALM and CALM-AF10 fusion mRNAs and clinical features

A fusion transcript of AF10 and CALM was isolated recently from the U937 ce ll line with t(10;11)(p13;q21). We performed reverse transcription-polymera se chain reaction and sequencing analysis on the t(10;11) leukemia samples obtained from four patients and one cell line, and we identified reciprocal fusion transcripts of AF10 and CALM in all the samples. The fusion transcr ipts in the five samples showed four different breakpoints in AF10 and thre e different breakpoints in CALM. In addition, the fusion transcripts in one sample showed a nucleotide sequence deletion in AF10, and those in two sam ples showed a nucleotide sequence deletion in CALM; the deletions were thou ght to be caused by alternative splicing. The variety of breakpoints and sp lice sites in the two genes resulted in five different-sized AF10-CALM mRNA s and in four different-sized CALM-AF10 mRNAs. Clinical features of 11 pati ents, including 6 of our own and 5 reported by others, in whom the fusion o f AF10 and CALM was identified, are characterized by young age of the patie nts, mixed-lineage immunophenotype with coexpression of T-cell and myeloid antigens, frequent occurrence of a mediastinal mass, and poor clinical outc ome. Genes Chromosomes Cancer 25:33-39, 1999. (C) 1999 Wiley-Liss, Inc.