Upregulation of MEL1 and FLJ42875 genes by position effect resulting from a t(1;2)(p36;p21) occurring during evolution of chronic myelomonocytic leukemia

Upregulation of a gene can result from its juxtaposition to an active regulatory element consequently to a chromosomal translocation. A paradigmatic example of this phenomenon, known as “position effect”, is the activation of oncogenes translocated closely to immunoglobulin or T cell receptor chain loci in hematological malignancies. A similar position effect has been invoked to explain the overexpression of PRDM16 (1p36.32) or PRDM3 (3q26) when translocated to a 3q21 domain where a putative enhancer element has been hypothesized [1,2]. PRDM3 has been reported to be also overexpressed following its juxtaposition to a large domain at 2p16-21 [3]. Here we report a case of transcriptional upregulation of PRDM16 and FLJ42875 (1p36.12) following a translocation juxtaposing them to 2p21, therefore strongly supporting the opinion that this 2p domain harbors regulatory elements able to overexpress juxtaposed genes.