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Screening Tests for Newborns: Inherited (Genetic) Disorders
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Generally speaking, genetic tests fit into three categories: those considered because of a family history of the disease, those considered because the disease is common in the family’s ethnic groups, and those that may be random or be indicators of a future risk.
Family history: When parents are concerned that a certain disease runs in their families (for example, Duchenne muscular dystrophy, cystic fibrosis, fragile X syndrome, or other chromosome disorders), they may request that their newborn be tested for the disease. Often, a screening test can be done during pregnancy instead of after birth. While testing for cystic fibrosis may be ordered because of family history, its frequency in the population at large means that testing is now recommended for all newborns, and many states include this test in their newborn screening panel.
Ethnic group: When parents are concerned because a certain disorder is common among their ethnic groups (for example, Tay-Sachs disease, thalassemia, sickle cell anemia, cystic fibrosis, or congenital adrenal hyperplasia (CAH)), they may request that their newborn be tested. In this case, too, the parents may prefer, if possible, to have a screening test done during pregnancy instead of after birth. The national standards announced in 2006 by the American College of Medical Genetics advise screening all newborns for sickle cell anemia, hemoglobin S/beta-thalassemia, cystic fibrosis, and CAH. Currently, almost all states screen newborns for sickle cell anemia, and many screen for CAH and cystic fibrosis.
Other risks: Less frequently, some parents request that their newborn’s DNA be tested to identify a condition that may not become evident or have an effect until later in life (for example, Huntington disease, type 1 diabetes, and some forms of breast, ovarian, and colon cancer). Some parents value the information and want to be on the lookout for improvements in diagnosis, prevention, and treatment.
In some cases, one or both of the parents can be tested before or during a pregnancy to determine if they are carriers of these gene-based disorders. Fluids from the fetus can also sometimes be tested during the pregnancy to detect suspected conditions. See the articles Pregnancy and Prenatal Testing and The Universe of Genetic Testing for more information.
Genetic tests can be run on various types of body fluids and tissues. DNA testing, for example, can be done on a tiny sample of blood, skin, bone, tissue, or even hair. For some conditions, chromosomes are examined for abnormalities; for other diseases, a single gene is analyzed.
It should be noted that some genetic tests will identify a condition for which there is no treatment or cure and no changes can be made to improve the child’s quality of life. The value of such test results is controversial.
Sources
S1
National Newborn Screening and Genetics Resource Center. National Newborn Screening Status Report. Updated 17 Oct 2007. PDF available for download at http://genes-r-us.uthscsa.edu. Accessed 20 Nov 2007.
S2
Chicago Center for Jewish Genetics Disorders. Genetic screening and counseling. Available on the internet through http://www.jewishgeneticscenter.org. Accessed 27 Nov 2007.
S3
Genetic Science Learning Center, Eccles Institute of Human Genetics, University of Utah. What are genetic disorders? Available on the internet through http://gslc.genetics.utah.edu. Accessed 27 Nov 2007.
S4
National Women’s Health Resource Center Inc. Genetic testing. Last updated 12 May 2005. Available on the internet through http://www.healthywomen.org. Accessed 27 Nov 2007.
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This article last reviewed on March 16, 2008.
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