A phenotypically normal donor for bone marrow transplantation was found to have a previously unreported karyotype, 46, XY, t(18q+;22q-), resulting in a Ph'-like chromosome. Identification of the Ph'-like chromosome in cultures of skin fibroblasts, phytohemaglutinin-stimulated peripheral blood cells, and bone marrow cells from the marrow donor, but not in cell cultures from siblings or parents, indicated that it represented an acquired somatic mutation. Demonstration of the Ph'-like chromosome in the marrow graft recipient's blood and bone marrow cells after transplantation provided a unique and definitive marker of engraftment. Hematopoiesis appeared normal in both the donor and recipient after transplantation. This study indicates that a mutation creating a Ph'-like chromosome in hematopoietic cells need not produce hematologic abnormality. Presence of this translocation did not appear to interfere with normal hematopoietic or lymphoid differentiation and replication in the transplant setting.
Cytogenetic studies in a patient with chronic myelocytic leukemia (CML) demonstrated the emergence of an extremely hypodiploid cell line at the time of blast crisis, a modal chromosome number of 35, with the modal karyotype 35,XY, -3, -4, -5, -7, -9, -11, -12, -13, -15, -16, -17, -19, -20, -22, + t(9;22) (q34;q11, + Mar1, + Mar2, + Mar3. Giemsa-banding confirmed complex chromosome rearrangements and demonstrated distinct banding patterns for the marker chromosomes. Cytologic characteristics of the leukemia blasts were predominantly myeloid. There was no important clinical response to chemotherapy, including vincristine and prednisone, or to radiotherapy.
A-29-year-old white man with acute undifferentiated leukemia had bone marrow cells with predominantly 42 chromosomes including several rearrangements. Following a brief induced "complete" remission, during which normal chromosomes were observed, bone marrow cells with 42 chromosomes but a different karyotype than before remission were found. Evaluation of that karyotype indicates not only a reduced chromosome count but also a reduced quantity of chromosome material.
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