A BCR-ABLp190 Fusion Gene Made by Homologous Recombination Causes B-Cell Acute Lymphoblastic Leukemias in Chimeric Mice With Independence of the Endogenous bcr Product

Translocations, cancer and the puzzle of specificity

The finding of acquired chromosomal translocations that are consistently associated with specific tumour types supports the premise of lineage-specific mechanisms of tumorigenesis. We review the evidence indicating that the specificity of these translocations and the corresponding gene fusions is related to biological constraints at the level of recombination, expression, and protein function. A dynamic relationship between the gene fusion and the cellular environment is proposed in which the environment influences the selection of oncogenic fusions and the oncogenic fusion in turn influences the cellular environment.

Molecular genetics of childhood leukemias

PURPOSE

This review summarizes the molecular genetics of childhood leukemias, with emphasis on pathogenesis and clinical applications.

DESIGN

We first describe the most common genetic events that occur in pediatric acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML), and chronic myeloid leukemia (CML). We then illustrate how these molecular alterations may be used to alter therapy.

RESULTS

In childhood ALL, the TEL-AML1 fusion and hyperdiploidy are both associated with excellent treatment outcomes and therefore identify patients who may be candidates for less intensive therapy. In contrast, MLL gene rearrangements and the BCR-ABL fusion confer a poor prognosis; these patients may be best treated by allogeneic bone marrow transplantation in first remission.

CONCLUSIONS

Although clinical features are important prognostic indicators, genetic alterations of leukemic blasts may be better predictors of outcome for acute leukemia patients. We therefore favor risk-adapted therapy based on classification schemes that incorporate both genetic and clinical features.