What type of testing is available to determine whether a child has a genetic birth defect?
The following chromosome studies may help to determine whether a child has a genetic birth defect: • Karyotype The chromosomes need to be stained in order to see them with a microscope. When stained, the chromosomes look like strings with light and dark “bands.” A picture (an actual photograph from one cell) of all 46 chromosomes, in their pairs, is called a “karyotype.” A normal female karyotype is written 46, XX, and a normal male karyotype is written 46, XY. The standard analysis of the chromosomal material evaluates both the number and structure of the chromosomes, with an accuracy of over 99.9 percent. Chromosome analyses are usually done from a blood sample (white blood cells), prenatal specimen, skin biopsy, or other tissue sample. Chromosomes are analyzed by specially trained healthcare personnel that have advanced degrees in cytogenetic technology and genetics. “Cytogenetics” is a word to describe the study of chromosomes. In a karyotype, the chromosomes can look bent or twist
