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.