Fluorescent in situ hybridization of DNA probes in the interphase and metaphase stages of the cell cycle.

In the past decade, fluorescent in situ hybridization (FISH) has been used routinely in detecting molecular abnormalities in the interphase and metaphase stages of the cell cycle. Many of the molecular anomalies which are detected in this manner are diagnostic of a prenatal, postnatal, or neoplastic genetic disorder. With the continuous isolation of commercially available DNA probes specific to a particular chromosome region, FISH analysis has become standardized in its ability to detect characteristic chromosomal anomalies in association with genetic and neoplastic diseases. In recent years, FISH has also become automated to accommodate the increased volume of slide preparations necessary for the number of DNA probes needed to detect characteristic molecular anomalies in cancer tissues and bone marrow samples. FISH technology provides essential information to the physician regarding the diagnosis, response to treatment, and ultimately the prognosis of their patients' disorder. It has become an important source of information routinely used in conjunction with chromosome analyses, and presently to confirm molecular alterations detected by array comparative genomic hybridization (aCGH) analyses. In this chapter we describe the methods for performing FISH analyses in order to determine the presence or the absence of genetic abnormalities which define whether the patient has either a genetic syndrome or malignant disease.

Alpha- and beta-synucleins are new diagnostic tools for acute erythroid leukemia and acute megakaryoblastic leukemia.

α-Synuclein is a key component of the Lewy body, a large globular protein complex that forms in the nervous system of patients with Parkinson disease and other dementias [1-3]. Since α-synuclein also occurs in megakaryocytic and erythroid lineages [4-7], we wondered what role synucleins had in the hematopoietic system. Therefore, we studied the expression of α-, ß-, and γ-synucleins in a comprehensive panel of patient bone marrows and leukemic cell lines. We observed under expression of α-synuclein in the megakaryocytes of myeloproliferative neoplasm (MPN), but not normal reactive marrow (NRM) or myelodysplastic syndrome (MDS). Conversely, we observed over expression of ß-synuclein in the blasts of megakaryoblastic leukemias (MegL), but not acute myeloid leukemia (AML) or erythroleukemia (EryL), suggesting that α- and ß-synucleins could be useful adjunct markers for the early detection of MDS and the differential diagnosis of EryL and MegL from other AMLs.

Association of MLL amplification with poor outcome in acute myeloid leukemia.

Chromosomal rearrangements and amplification of the MLL gene at 11q23 are common abnormalities found in patients with severe myelodysplastic disorders and lymphoid and acute myeloid leukemias. MLL rearrangements are associated with aggressive disease in both children and adults, with current evidence suggesting that MLL alterations are associated with a poor prognosis. We report the clinical, cytogenetic and histologic findings of a patient who presented with a de novo diagnosis of AML-M4 and who fits the profile of patients presenting with MLL alterations, such as old age at presentation, rapid progression, therapeutic refractoriness, and poor outcome. Two bone marrow specimens taken 1 month apart show the rapid deterioration of the patient's cytogenetic abnormalities at the 11q23 locus, with amplification of MLL that was originally seen as a homogeneously staining region (hsr) on chromosome 11. In the second biopsy the hsr and MLL amplification appears as nonreciprocal translocation of multiple copies in the form of marked amplification of MLL on chromosome 16 in a background of increasing chromosomal aberrations. This case suggests that either the MLL amplification and translocation alone or in conjunction with other flanking oncogenes may have played an important role in poor patient outcome.