Newborn screening (NBS) is a public health service provided by each state. The purpose of this population screening effort is to identify pre-symptomatic infants (meaning the infant appears healthy and there are no symptoms yet) with conditions for which early treatment can prevent or reduce the severity of the clinical features. About 4 million babies undergo NBS each year in the United States. More than 1 in 300 newborns have a treatable condition identified through NBS1.
What is the difference between a screening and diagnostic test?
A screening test is given to those who have no symptoms of the condition in question. A diagnostic test is used to confirm a suspected condition once initial testing has revealed its possibility. Therefore, NBS cannot confirm or rule out a condition. Instead, if a positive newborn screen is detected, a newborn’s pediatrician will immediately be notified so diagnostic follow-up testing can be performed.
A brief history on newborn screening:
1960s: The first simple, inexpensive NBS for phenylketonuria (PKU) was developed1.
1990-1993: Tandem mass spectrometry (a laboratory method) was developed to be used in NBS2.
2005: The American College of Medical Genetics (ACMG) determines the Recommended Uniform Screening Panel (RUSP), a list of conditions all states should screen3.
2007: The Newborn Screening Saves Lives Act was established creating grants for follow-up care and public health education1.
2011: The Center for Disease Control declares NBS as part of the “Ten Great Public Health Achievements.4”
What are the newborn screening procedures?
Testing is generally performed when a baby is between 24-48 hours old5. NBS is required and not dependent on parent’s health insurance status. While all states require NBS, most will allow screening refusal for religious purposes6. NBS consists of three tests5:
Blood test (heel stick): The baby’s heel is pricked to collect drops of blood onto the filtered paper card. The dried blood spots are then sent to the state laboratory for analysis.
Hearing screen: The Otoacoustic Emissions (OAE) Test and/or Auditory Brain Stem Response (ABR) Test are performed. The OAE test determines if certain parts of the baby’s ear respond to sound and the ABR test evaluates the auditory brain stem and the brain’s response to sound.
Pulse oximetry: A non-invasive test that measures how much oxygen is in the blood.
What is the process and clinical impact of a positive newborn screening?
To illustrate the process and clinical impact of NBS, we will use PKU as an example. PKU is a condition in which the body cannot break down an amino acid called phenylalanine (Phe). Phe is found in many foods and in an artificial sweetener called aspartame. If left untreated, individuals with PKU will have Phe build up in the blood which causes permanent nervous system and brain damage, seizures, psychiatric problems, severe intellectual disability, or even death. However, when detected by NBS early treatment can begin and these individuals can live healthy lives5.
Phe levels are tested in the dried blood spots collected from the heel stick. If an infant has an out-of-range screening result they will need to be seen by their pediatrician for confirmatory testing. It is important to remember an out-of-range screening result does not mean an infant has PKU, as there can be false positives. Confirmatory tests include checking blood and urine levels, and may also include genetic testing to identify the mutations that cause PKU in the PAH gene. After a diagnosis is confirmed, the infant will be placed on a restricted diet that includes phenylalanine-free medical formula as well as foods modified to be low in protein.
What conditions are included in newborn screening?
The conditions included vary between states. Most states test for conditions included on the RUSP. Some states have additional conditions on their NBS panel. Determine what conditions are included on the NBS panel in your state here. Of note, not all genetic conditions for which early detection is important are evaluated as a part of NBS. For example, there are hundreds of deletion and duplication syndromes that can cause neurodevelopmental delays, early onset seizures, congenital (present from birth) abnormalities, and other health concerns. These deletion and duplications syndromes are identified through diagnostic testing such as the MyDevelopingChild Essential test.
Can new conditions be added?
ACMG also came up with procedures for adding conditions to the RUSP, namely that a condition should meet three minimum criteria3:
The condition can be detected 24 to 48 hours after birth, when it cannot usually be detected by a doctor's exam.
It has a test that is specific and sensitive for the condition.
Its early detection, timely intervention, and effective treatment offer proven benefit.
Early detection through NBS can prevent severe health problems or even death.
Every baby born in the United States will be screened unless a parent decides to opt out for religious reasons.
The conditions newborns are screened for differ by state.
NBS does not diagnose a child with a condition. If a positive screen is detected, parents will be notified immediately and follow-up testing will be done.