Detecting chromosomal abnormalities is important for prenatal diagnosis, detection of carrier status, and for general diagnostic purposes. One of the ways to determine whether chromosomes are normal or abnormal is by obtaining an individual's karyotype. A karyotype is a technique that allows geneticists to visualize metaphase chromosomes under a microscope.

Karyotype analysis can be performed on virtually any population of rapidly dividing cells either grown in tissue culture or extracted from tumors. Chromosomes derived from peripheral blood lymphocytes are ideal because they can be analyzed three days after they are cultured. Lymphocytes can be induced to proliferate using a mitogen (a drug that induces mitosis) like phytohemagglutinin. Skin fibroblasts, bone marrow cells, chorionic villus cells, tumor cells, or amniocytes also can be used but require up to two weeks to obtain a sufficient amount of cells for analysis. The cultured cells are...