Carrier screening is a type of genetic testing performed on people who display no symptoms for a genetic disorder but may be at risk for passing it on to their children. A carrier for a genetic disorder has inherited one normal and one abnormal allele for a gene associated with the disorder. A child must inherit two abnormal alleles in order for symptoms to appear. Prospective parents with a family history of a genetic disorders are candidates for carrier screening.
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Carrier screening is really a specific type of genetic screening, again, that we apply to a large population of people who don't have any symptoms of the disease. But they may be at risk for passing it along to their children or potentially may develop the disease later in their life. When we think of carrier screening, we think of it in the context of both autosomal recessive conditions and X-linked recessive conditions, because in each case, the parent carries a single copy of the poorly functional gene, them not being affected with the condition, yet their children are at risk for having the condition. Some of the examples of diseases that we do carrier testing for are things like cystic fibrosis, Tay-Sachs disease, sickle cell disease, hemophilia, and Fragile X syndrome.
Donald W. Hadley, M.S., C.G.C.
Associate Investigator, Social and Behavioral Research Branch, Public Health Genomics Section; Associate Director, Office of Clinical Liaison, Office of the Clinical Director
Mr. Hadley is a genetic counselor and a clinical researcher. As a genetic counselor, he provides education and counseling for people participating in NIH clinical protocols who have or at risk for inherited diseases. As a researcher, he evaluates methods for educating and counseling families with genetic conditions. His research is performed within the Public Health Genomics Section. Mr. Hadley strives to understand the psychological and behavioral outcomes of the counseling and testing process. His clinical role gives him insight into concerns of families considering genetic testing and the issues they deal with following their decisions.