Chromosome analysis or karyotyping is a test that evaluates the size, shape, and number of chromosomes. Extra or missing chromosomes, or abnormal locations of chromosome pieces, can cause problems with growth, development, and physical functions. Chromosome analysis is usually a helpful test to determine the genetic contribution to a constellation of medical and/or developmental problems. In addition, stem cells in culture can accumulate changes including chromosomal abnormalities. Alterations in the genome can lead to changes in gene expression and cellular functions, increasing the risk of stem cell tumorigenesis. Therefore, it is crucial to monitor a culture for any chromosomal abnormalities, particularly in stem cells intended for therapeutic use.
Traditional karyotyping uses dye to stain the chromosomes of a metaphase cell in distinct banding patterns. The most common method is Giemsa staining, also known as G-band karyotyping or G-banding, other methods include C-banding (constitutive heterochromatin staining), Q-banding (quinacrine staining), R-banding (reverse Giemsa staining), and T-banding (telomeric staining).
- Classic karyotyping
- Spectral karyotyping
- Digital karyotyping
The karyotyping examines a person's chromosomes to determine if there is a right number and to determine if each chromosome appears normal. It requires experience and expertise to perform properly and to interpret the results. Although theoretically almost any cells could be used for testing, in practice it is usually performed on fresh blood, bone marrow, prenatal specimens, solid tissue specimens, and fixed specimens.
