Cytogenetic oligoclonality resulting from jumping translocation and isodicentric Xq 13 as evidenced by FISH

Abstract

We describe a case of acute myeloid leukemia (AML) that had transformed from myelodysplastic syndrome (MDS) where cytogenetics revealed the presence of 5 unrelated clones in the bone marrow aspirate - 4 clones with chromosomal abnormalities and 1 which was karyotypically normal. Fluorescence in situ hybridization (FISH) using a combination of library - centromeric probes and library - library probes revealed jumping translocation as one of the causes of the cytogenetic oligoclonality. Different segments of the long arm of chromosome 1 ( 1q) had jumped onto the ends of three chromosomes namely 8q, 9q and 18q, resulting in the development of three cytogenetically unrelated clones. A fourth clone showed an isodicentric chromosome of Xq. This is an unusual case of cytogenetic oligoclonality in MDS-AMLshown explicitly by FISH to have arisen from two separate events, namely jumping translocations of 1q and isodicentric formation involving Xq 13.