AF15q14, a novel partner gene fused to the MLL gene in an acute myeloid leukaemia with a t(11;15)(q23;q14)

In haematopoietic malignancies the MLL gene, located on chromosome 11q23, i s frequently disrupted by chromosome rearrangement, generally resulting in fusion to various partner genes. We have previously reported a t(11;15)(q23 ;q14) in a case of acute myeloblastic leukaemia. Here, we report the clonin g of a novel MLL partner, AF15q14, at chromosome 15q14, In this translocati on, the breakpoint occurred in exon 8 of MLL and exon 10 of AF15q14. The no rmal AF15q14 transcripts of approximately 8.5 kb in size, are expressed in different tumoral cell lines, in variety of normal tissues, and in all the foetal tissues tested. Sequencing of AF15q14 cDNA revealed a putative open reading frame of 1833 amino acids that had no homology with any other known protein. The C-terminal end of the putative AF15q14 contained a bipartite nuclear localization site. The translocation t(11;15) preserved the open re ading frame between MLL and the 3' end of AF15q14. The contribution of AF15 q14 to the fusion protein was only 85 amino acids, Immunofluorescence stain ing experiments with expression vectors encoding these 85 amino acids confi rmed the functionality of the predicted nuclear localization site.