A NOVEL GENE, AF1Q, FUSED TO MLL IN T(1-11)(Q21-Q23), IS SPECIFICALLYEXPRESSED IN LEUKEMIC AND IMMATURE HEMATOPOIETIC-CELLS

Translocations involving chromosomal band 11q23 are associated with le ukemias. These translocations fuse the MLL, a gene with sequence homol ogy to the Drosophila trithorax, to genes from a number of other chrom osomal loci. We have characterized two t(1;11)(q21;q23) translocations that fuse the MLL gene to a novel gene, AF1q on chromosomal band 1q21 , in two infants with acute myelomonocytic leukemia (AMMOL). In one of these patients, der(11) represents an in-frame fusion of the N-termin al portion of MLL gene to the complete AF1q open reading frame, wherea s der(1) does not give rise to an open reading frame. This observation suggests that the N-terminal portion of MLL gene is critical for leuk emogenesis in translocations involving band 11q23. The predicted wild- type AF-1q product is a 9-kD protein with no similarity to any other p rotein in the data banks. The AF1q mRNA is highly expressed in the thy mus but not in peripheral lymphoid tissues. In contrast to its restric ted distribution in normal hematopoietic tissue, AF1q was expressed in all leukemic cell lines tested. (C) 1995 by The American Society of H ematology.