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Inversion of chromosome 16 and dysplastic eosinophils in accelerated phase of chronic myeloid leukemia
H Enright1, D Weisdorf, L Peterson
1Department of Medicine, University of Minnesota, Minneapolis.
Abstract:
Abnormalities of chromosome 16, including inv(16)(p13q22), del(16)(q22), and t(16;16)(p13;q22), have been reported almost exclusively in association with acute myelomonocytic leukemia and are characteristically accompanied by abnormal eosinophils with dysplastic granules in the bone marrow. We observed an inv(16)(p13q22) in two patients with typical Philadelphia chromosome positive chronic myeloid leukemia (CML). The appearance of the abnormality of chromosome 16 was associated with acceleration of disease or onset of blast crisis and with the appearance in the bone marrow of abnormal eosinophils. In both cases the marrow karyotypes were 46,XY,t(9;22)(q34;q11)/46,XY,inv(16)(p13q22),t(9;22)(q34;q11). In these two patients the temporal association of the acquisition of the inversion 16 and the appearance of monocytoid cells and dysplastic eosinophils in the bone marrow further supports the relationship of this karyotypic abnormality with leukemic monocytoid and eosinophilic evolution. This secondary cytogenetic change appears to be an infrequent manifestation of specific phenotypic disease progression in CML.
Insights
Chromosome 16 abnormalities, typically seen in acute myelomonocytic leukemia, were observed in chronic myeloid leukemia (CML) patients. This secondary genetic change correlated with disease acceleration and abnormal eosinophils.
Area of Science:
- Hematology
- Cytogenetics
- Oncology
Background:
- Chromosome 16 abnormalities, specifically inv(16)(p13q22), del(16)(q22), and t(16;16)(p13;q22), are strongly associated with acute myelomonocytic leukemia (AMML).
- These cytogenetic changes in AMML are characteristically accompanied by dysplastic eosinophils in the bone marrow.
Observation:
- An inversion of chromosome 16, inv(16)(p13q22), was identified in two patients with Philadelphia chromosome-positive chronic myeloid leukemia (CML).
- The emergence of the chromosome 16 abnormality coincided with disease acceleration or the onset of blast crisis in these CML patients.
Findings:
- Both CML patients presented with the karyotype 46,XY,t(9;22)(q34;q11)/46,XY,inv(16)(p13q22),t(9;22)(q34;q11), indicating a secondary cytogenetic event.
- The appearance of abnormal eosinophils and monocytoid cells in the bone marrow was temporally linked to the acquisition of the inv(16)(p13q22) abnormality.
Implications:
- The findings suggest that inv(16)(p13q22) can be a secondary cytogenetic abnormality in CML, not exclusively associated with AMML.
- This cytogenetic change appears to signify a specific phenotypic progression in CML, leading to leukemic evolution involving monocytoid and eosinophilic lineages.
- The study highlights an infrequent but significant mechanism of disease progression in CML, emphasizing the importance of comprehensive karyotypic analysis.