Changes in Cancer

Cytogenetic Changes in Cancer

Aneuploidy and Aneusomy

Initially, most of the cytogenetic studies of tumor progression were carried out in leukemias because the tumor cells were amenable to being cultured and karyotyped by standard methods. For example, when CML, with the 9;22 Philadelphia chromosome, evolves from the typically indolent chronic phase to a severe, life-threatening blast crisis, there may be several additional cytogenetic abnormalities, including numerical or structural changes, such as a second copy of the 9;22 translocation chromosome or an isochromosome for 17q. In advanced stages of other forms of leukemia, other translocations are common. In contrast, a vast array of chromosomal abnormalities are seen in most solid tumors. Cytogenetic abnormalities found repeatedly in a specific type of cancer are likely to be driver chromosome mutations involved in the initiation or progression of the malignant neoplasm. A current focus of cancer research is to develop a comprehensive cytogenetic and genomic definition of these abnormalities, many of which result in enhanced proto-oncogene expression or the loss of TSG alleles. Whole-genome sequencing is replacing cytogenetic analysis in many instances, because it provides a level of sensitivity and precision well beyond detection of cytologically visible genome changes.

Gene Amplification

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Nov 27, 2016 | Posted by in GENERAL & FAMILY MEDICINE | Comments Off on Changes in Cancer

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