Abnormal Chromosomes in Cancer
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Picture A
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A normal cell contains 46 chromosomes, consisting of 22 pairs (one from each parent) plus the X and Y chromosome (male) or X and X (female), for a total of 23 pairs. When the chromosomes are "painted" to aid researchers with analysis, each of the 23 pairs is distinguished by a distinct color, as in picture A. Picture A depicts an orderly array of chromosomes from the largest to smallest pair, cut from a metaphase spread of blood lymphocytes from a normal healthy individual. This is known as a karyotpe.
(Metaphase is the stage of cell division in which duplicated chromosomes become aligned along the center of the cell prior
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Picture B1
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to their moving to the poles followed by cell division.)
Picture B1 depicts a metaphase spread of a multiple myeloma plasma cell. Picture B2 depicts a karyotype of the same cell. The karyotype is abnormal; the number of chromosomes in this case is much higher than normal, which is consistent with numerous chromosome duplications. In some cases fewer than two chromosomes can be seen, indicating that a chromosome deletion has occurred (deletion of chromosome 13 is common in myeloma). Many chromosomes are multicolored, indicating that chromosome fusions, or so called "translocations," have occurred.
Researchers at the Myeloma Institute are working to understand the basis for this genetic chaos by differentiating which karyotypic abnormalities typically recur and likely harbor "driver" genes. Through a combination
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Picture B2
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of spectral karyotyping and gene expression profiling, which measures the activity of the thousands of genes buried in each chromosome, Myeloma Institute researchers are making significant strides in unraveling the mysteries of myeloma development. The goal is to use these insights to apply current treatments as effectively as possible and to develop new therapies based on knowledge of the molecular abnormalities that cause myeloma.
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