Testing for Birth Defects There are many types of tests that may be performed to determine whether a child has a genetic birth defect. Listed in the directory below are some, for which we have provided a brief overview. If you cannot find the information in which you are interested, please visit the Medical Genetics Related Web sites page to view a list of Web sites that may contain additional information on that topic. Chromosome Studies: Karyotype, Extended Banding, Fluorescent In Situ Hybridization (FISH) Studies for Single Gene Defects: DNA (Direct and Indirect) Biochemical Genetic Testing Return to the Genetics Home Page Return to the Disorders, Diseases and Organ Topics Home Page