Genetic Testing for Newborns

newborn genetic testing

Original image courtesy of nickmealey (Flickr)

If you live in the U.S. and most other western nations, your newborn will undergo a series of genetic tests at birth. Depending on where you live, the extent of genetic testing for newborns can vary. These tests are designed to keep your baby healthy by finding potential disorders very early. None of this is nearly as frightening as it sounds. The disorders that newborn screening programs test for are very rare, and they’re virtually all actionable — meaning that if your child has one, some form of treatment is available.

In this article, we’ll cover the essentials you need to know about genetic testing for newborns and provide links to reliable sources for additional information.

How Are Newborns Tested?

Generally, it happens like this: a nurse takes a tiny blood sample by heel stick when your baby is about 24 hours old. The blood sample will be sent to a newborn testing lab for genetic screening. The results will be returned to the hospital and your baby’s pediatrician in about 10-14 days. There may be additional follow-up tests required, which can take several more days.

The results of your newborn’s tests will be sent to your pediatrician. You may never hear anything, but you should ask the doctor if they’ve come back yet, just to be sure.

Genetic Conditions Tested For

The conditions that newborns are screened for vary from state to state, and in many states, the list is growing. Right now, there are around 30 “core” conditions recommended for testing by the National Newborn Screening & Global Resource Center, and they generally fall into these categories:

  • Amino acid disorders. These are deficiencies in enzymes that normally process amino acids, which are the “building blocks” of proteins. Phenylketonuria (PKU) is a well-known amino acid disorder in which the body can’t break down phenylalanine. 
  • Fatty acid oxidation disorders. In general, these are disorders in breaking down fat into energy for use by the body, and they occur because one of the required enzymes is missing or not working properly.
  • Organic acid disorders. Deficiencies of certain enzymes that the body makes, such as methylmalonic acid, can lead to problems processing the protein in foods that we eat.
  • Other inherited disorders. These include well-known genetic diseases such as cystic fibrosis, sickle cell disease, and alpha thalassemia.

Importantly, most of these disorders are rare, and nearly all are recessive (meaning that two defective copies of a gene must be inherited to cause them).

Why We Screen Newborns for Disorders

Some parents have concerns about tests of these nature being performed on their baby. In many states this is irrelevant, as newborn screening tests are mandated by law. Even if you live in a state that allows you to opt-out, I sincerely hope that you won’t. Newborn screening is a good thing: it identifies very rare, very serious inherited conditions so that doctors can intervene.

Let’s take phenylketonuria (PKU) as an example. This is a rare, autosomal recessive disorder caused by mutations in the gene for phenylalanine hydroxylase (PAH). If you have one non-functional copy of the gene, you’re fine. If you have two, your body is unable to break down the amino acid phenylalanine into another (crucial) amino acid, tyrosine.

Without treatment, PKU can cause mental retardation, seizures, and a host of other serious issues. However, management of the condition (with diet and possibly medication) allows your baby’s brain to develop normally. Even though it’s a rare disorder (1 in 10,000 among Caucasians in the U.S.) it’s certainly something parents should know about.

If Your Newborn Is Affected

If any of the tests come back positive, the hospital and/or your pediatrician may order a follow-up, confirmatory test. They will also begin discussing the results with you. Most states only screen for “actionable” disorders, meaning that there’s something to be done for a newborn that has one. You can and should find out everything about this disorder, first from your doctor, then from trusted resources such as the NIH’s National Center for Biotechnology Information.

Don’t rely blindly on Google! There’s way too much information out there, and most of it goes unvetted.

Genetic Testing and Genetic Counseling

Genetic information is rapidly becoming available to anyone who wants it. Advances in DNA sequencing technology, and direct-to-consumer services like 23andMe have raised concerns that genetic information could be mis-used if it fell into the wrong hands. In 2008, U.S. legislators passed the Genetic Information Non-Discrimination Act (GINA) which made it illegal for insurance companies and employers to discriminate based on genetic information. Similar laws have been passed in many countries. This should be a comfort to parents whose child has a rare genetic condition.

Also, before I forget: There are trained professionals out there called genetic counselors. These can be wonderful resources for learning about the relative risks of genetic disorders. If you have concerns (even before starting a family), ask your pediatrician to refer you to one.