No abstract

The karyotype of leukemic cells of 78 acute leukemia patients (37 ANLL, 34ALL, and 7 of unknown type) was studied by means of G-banding. Chromosomal abnormalities were found in 50 patients (72%). Chromosomes 8,21,5,7,11, and 19 were preferentially involved in the abnormalities, both in ANLL and in ALL. A high incidence of the characteristic rearrangement t(8;21) was noted in AML: (in 6 of 22 AMP patients). An identical reciprocal translocation--t(4;11)--was seen in 4 out of 34 ALL patients.

Results of chromosome studies of blood and bone marrow cells from 101 patients with Ph1 positive chronic myeloid leukemia (CML) confirm the assumptions that clinical and morphologic manifestations of the disease correlate with karyotype peculiarities of leukemia cells. Several variants of the clinical course of CML may be distinguished. One is the variant with a short chronic phase and a comparatively long terminal phase. In blastic crisis the blast cells are peroxidase negative and do not possess cytoplasmic inclusions. Acute transformation occurs without any additional chromosome damage. The second, more common form is less severe because of longer chronic phase but it has a short and grave acute stage. The blast cells present definite signs of myeloid differentiation, they have basophilic or neutrophilic cytoplasmic granules and are peroxidase positive. Marker i(17q) often combined with trisomy 8 is a characteristic chromosome abnormality in the terminal stage of this variant. The third type has an extremely long chronic phase but ends in a rapidly progressing severe and resistant to therapy "lymphoid" blastic crisis. Blast cells have typical "lymphoid" morphology, they are peroxidase negative and contain granular PAS positive substance. Various additional chromosome changes appear in the terminal stage. Future studies of a larger series of patients may possibly reveal more CML variants.

The karyotype of leukemic cells was studied in 88 acute nonlymphocytic leukemia (ANLL) patients. Chromosome abnormalities were discovered in 78.4% of all patients and in 72.5% of the 69 patients studied before treatment. Characteristic abnormalities: translocations 8;21, 15;17, 9;22 or 6;9, rearrangements of 11q, gain of chromosomes 8 or 21, and loss or deletion of chromosomes 5 or 7 were detected in 56 of 69 patients with abnormal karyotypes. Translocation 8;21 was revealed in 27 patients; 20 of them had M2 FAB-form, four had M1, and three had M4. In patients with t(8;21) the incidence of complete remission was higher and the duration of first remission and survival longer than in patients with other abnormalities or with a normal karyotype.

Rearrangement of the short arm of chromosome 6 with a breakpoint at 6p23 was found in five patients with myeloid leukemia. Three of them had different morphological variants of AML (M2, M3, M4) and two blastic crisis of Ph1 negative and Ph1 positive CML. Identical translocation, t(6;9)(p23;q34), was revealed in two patients. One of them had AML (M2), the other blastic crisis of Ph1 negative CML. The blast cells of the last patient were morphologically similar to those in the M2 variant of AML. Translocation (6;9)(p23;q34) was also detected in two AML patients of Rowley and Potter (1976). The role of the breakpoint at 6p23 in myeloid malignancies needs further investigation.