Cytogenetics (FISH)
Tissue Core | Cytogenetics (FISH) | Cellular Kinetics and VH studies
Cytogenetic abnormalities in B-cell CLL are important prognostic indicators for predicting disease progression and treatment response. Interphase FISH (Fluorescence In Situ Hybridization) is widely used in clinical practice to study patients with CLL. This technology is useful to detect specific gene anomalies and various aneuploid conditions in neoplastic cells. FISH can be performed on blood and bone marrow aspirates or smears, paraffin embedded tissues, touch preparations, and many other tissue preparations. Interphase FISH can be used to establish the percentage of neoplastic and normal cells in both interphase and metaphase cells before and after therapy, and therefore can be used to assess therapy and monitor remission. Some FISH tests can detect levels of disease that are less than 1% and are therefore particularly useful to study minimal residual disease, though most FISH assays for CLL have a normal cutoff of approximately 7%.
The most common cytogenetic anomalies in CLL involve chromosomes 6, 11, 12, 13, 14 and 17.
Chromosomal anomalies detected by interphase FISH are among the most important factors predicting survival in B-CLL(21). FISH-detected chromosome anomalies have also been associated with different clinical outcomes and may be associated with IGHv mutation status, CD38 expression, ZAP 70, antigen expression on leukemic B-lymphocytes, cell morphology and other biological features(2,3,27,29). Today many investigators use the following hierarchical risk model of FISH anomalies in B-CLL defined by Dohner et al. (27) and Dewald et al (21) with 17p- as the most aggressive and 13q-x1 as the least aggressive: 17p- ® 11q- ® 6q- ® +12 ® normal ® 13q-x2 ® 13q-x1.
The Tissue Core has standardized interphase FISH among the CRC cytogenetics sites (uniform scoring and data-entry). This validation has provided accurate interphase FISH studies for CRC clinical trials and CRC research investigators across the United States. In addition the CRC FISH information associated with each CRC CLL patient has used for genetic studies by Project 1 of this consortium.
| Daniel Van Dyke, Ph.D. Mayo Clinic |
Ayala Aviram, Ph.D. North Shore-Long Island Jewish Health System |
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CRC Cytogenetics/FISH Team |