Congenital and Genetic Disorders
Newborn screening tests help to identify potentially treatable or manageable congenital disorders within days of birth. Life-threatening health problems, mental retardation, and serious lifelong disabilities can be avoided or minimized if a condition is quickly identified and treated.
Screening tests recommended for all newborns
The Secretary's Advisory Committee on Heritable Disorders in Newborns and Children (SACHDNC), part of the U.S. Department of Health and Human Services, recommends that all newborns be screened for 31 core disorders and 26 secondary disorders. The tests are organized into broad categories:
- Metabolic disorders (e.g., phenylketonuria (PKU), galactosemia)
- Endocrine disorders (e.g., congenital hypothyroidism [CH] and congenital adrenal hyperplasia [CAH])
- Hemoglobin disorders (hemoglobinopathies; e.g., sickle cell anemia)
- Other disorders (e.g., cystic fibrosis)
A table of the recommended tests, adapted from the SACHDNC web site, is available here.
For information on of the specific disorders, see the March of Dimes: Recommended newborn screening tests page.
In the U.S., states regulate their newborn screening programs, so the number of screening tests performed varies from state to state. To see a list of newborn screening tests required or offered by state, go to the National Newborn Screening and Genetics Resource Center web site.
Physicians and parents may request a "supplemental newborn screening" panel in addition to the state-required tests. At some hospitals, you can indicate your preference for this more extensive testing when you check in for the birth. Supplemental newborn screening tests can also be arranged, in advance of the birth, through one of several private laboratories offering this service.
Reminders to parents:
- Parents should also be aware that special collection techniques are used with newborns to minimize discomfort during specimen collection. In most cases, all the tests can be done using just a few drops of blood obtained from a pricked heel. Requesting supplemental tests will usually not require extra heelsticks or blood from your newborn.
- Newborn screening tests are usually performed within 24 to 48 hours of life. For some tests, such as phenylketonuria (PKU) and congenital hypothyroidism (CH), it is important that they not be run too soon after birth. They may not accurately reflect whether a disorder is present if performed within the first 24 hours of life. Since women and their newborns may be discharged within a day or two of the birth, it is possible that a newborn could be tested with a sample taken within those first 24 hours. Consequently, some states routinely recommend screening two times, once in the hospital and then about 2 weeks later.
Screening for inherited disorders in newborns at risk
Screening tests for certain inherited diseases that are not already covered by mandatory statewide screening may be requested based on family history or ethnic background. Testing typically involves detecting the specific gene(s) associated with a disorder that occurs frequently within a family or members of a specific ethnic group. Parents may decide to ask for supplemental tests for their newborn in these situations:
- Family history: When parents are concerned that a certain disease runs in their families (e.g., Duchenne muscular dystrophy, fragile X syndrome, or other chromosome disorders), they may request that their newborn be tested for the disease. While testing for certain conditions such as cystic fibrosis may be ordered because of family history, for example, its frequency in the population at large means that testing is now recommended for all newborns. Every state's newborn screening program includes a test for CF, although the method used may vary, with some states performing only a test to determine the blood level of a chemical called immunoreactive trypsinogen (IRT) and others performing both an IRT and a DNA test when the IRT level is high.
- Ethnic group: When parents are concerned because a certain disorder is common among their ethnic groups (e.g., Tay-Sachs disease, thalassemia, sickle cell anemia, cystic fibrosis, or congenital adrenal hyperplasia (CAH)), they may request that their newborn be tested. Again, several of these disorders are already included in many states' newborn screening programs.
- Other risks: Less frequently, some parents request that their newborn's DNA be tested to identify a condition or risk of developing 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. Amniotic fluid can also sometimes be tested during the pregnancy. See the articles Pregnancy and Prenatal Testing and The Universe of Genetic Testing for more information.
Genetic tests can be run on blood, other types of body fluids, and tissues. 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.
National Newborn Screening & Genetics Resource Center: National Newborn Screening Status Report (Contains a table with each state's current requirements)
Sources Used in Current Review
KidsHealth.org. Newborn Screening Tests. Available online at http://kidshealth.org/parent/system/medical/newborn_screening_tests.html# through http://kidshealth.org. Accessed May 2012.
Genetics Home Reference. Congenital hypothyroidism. Available online at http://ghr.nlm.nih.gov/condition/congenital-hypothyroidism through http://ghr.nlm.nih.gov. Accessed May 2012.
MedlinePlus Medical Encyclopedia. Newborn screening tests. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/007257.htm. Accessed May 2012.
March of Dimes. Newborn screening tests. Available online at http://www.marchofdimes.com/professionals/bringinghome_screening.html through http://www.marchofdimes.com. Accessed May 2012.
Cystic Fibrosis Foundation. Cystic Fibrosis Newborn Screening. Available online at http://www.cff.org/AboutCF/Testing/NewbornScreening/ScreeningforCF/ through http://www.cff.org. Accessed May 2012.