Molecular genetics in acute and chronic leukemias

The application of molecular biological techniques in malignant hematologic diseases, particularly leukemias, has led to a rapid increase in knowledge and a deeper insight into the pathobiology of these diseases. Leukemia is a very heterogeneous disease on the molecular level. Clonal chromosomal abn ormalities can be found in the vast majority of cases. A broader understand ing of the underlying molecular changes has enabled the development of risk -adapted therapy regimens with improved outcome. One example is the applica tion of molecular genetic techniques for detecting small numbers of leukemi a cells after therapy ("minimal residual disease"). This allows the early p reclinical recognition and prevention of relapse. This study gives a short overview of the current status of molecular genetics in human leukemias and its implications for the therapy and prognosis of these diseases. The foll owing topics are covered: generation of oncogenic fusion genes or dysregula tion of protooncogenes by chromosomal translocations, detection of minimal residual disease based on clonally rearranged immunoglobulin or T-cell rece ptor genes or on leukemia-specific fusion genes, monitoring bone marrow chi merism after allogeneic transplantation by molecular genetic techniques, an d the role of oncogenic herpesviruses and retroviruses in human hematologic malignancies.