Chromosome Analysis
For the first half-century of clinical cytogenetics, analysis of chromosomes was an exercise in microscopy. This century, molecular methodologies are holding sway. However, it behoves the counselor to have a good understanding of how things used to be, not least because one often needs to make reference to the historical literature; albeit that it goes without saying, one must keep abreast of new developments. Modern cytogenomic reports are sophisticated documents, and those who read them, and who interpret them to patients and families, need to be well informed. This chapter provides a basic overview of the ways in which chromosomes may be analyzed. The particular distinction is made between the classical methodologies of the twentieth century, and the new molecular approaches largely developed in the twenty-first century.