Chimaeric oncoproteins resulting from chromosomal translocations in acute lymphoblastic leukaemia.

A major mode of proto-oncogene activation by chromosomal translocations concerns the creation of fusion genes which encode chimaeric proteins. The largest class of oncogenes identified to date is the transcription factors, which are involved in control of cellular proliferation and differentiation via regulation of target gene transcription. Protein chimaeras that result from translocations in childhood ALL include two which involve the 19p13.3 gene E2A and a large heterogeneous group involving HRX located at chromosome band 11q23. Functional studies demonstrate that E2A fusion proteins function as chimaeric transcription factors, and structural features suggest that HRX fusion proteins may have analogous properties.