Cytogenetics is the microscopic study of chromosomes, which can show abnormalities that represent genetic defects in the DNA that they contain. These abnormalities can be numerical (loss or gains of chromosomes) or structural (eg. translocations, inversions, deletions).
Chromosomal abnormalities can be associated with a specific constitutional abnormality that is in turn linked to a particular syndrome or phenotype.
Chromosome abnormalities can also confirm the presence of a specific disease or cancer and can often suggest a more specific diagnosis or prognosis. The abnormalities can be used to monitor remission and diagnose relapse, transformation or secondary disease. Increasingly, cytogenetic abnormalities indicate specific and targeted treatment regimes.
Conventional cytogenetic analysis relies on the culture of cells to produce metaphase chromosomes, where individual chromosomes can be visualised. Tissue therefore needs to be as fresh as possible with viable disease cells. Cells are processed and stained using “banding” techniques to produce a karyotype.