Not just the ‘PKU test’ anymore!
Many healthcare providers still refer to newborn screening as “the PKU test”, since PKU (phenylketonuria) was the first and only condition screened for
beginning in 1965. Thanks to the development of the blood spot card in 1963 by Dr. Robert Guthrie ,
all babies have a few drops of blood taken from their heel shortly after birth. We started out by looking for only PKU, and in the past 50 years, countless
individuals with PKU have been identified and started on treatment – treatment that has prevented intellectual disability, seizures, and growth problems,
and that’s amazing!
But newborn screening didn’t stop there!
Today’s test is so much more thanks to a combination of new technologies and new treatments. Technology has rapidly advanced in the 50-plus years of the
newborn screening era, allowing us to detect many more disorders. A lot gets done with those few drops of blood – metabolic testing, hemoglobin testing,
and more. Testing for some of the newest additions to the newborn screen, lysosomal storage disorders, only requires a tiny fraction of the blood collected
from each baby, but requires new, high-tech instruments in the laboratory. Newborn screening now goes even beyond the blood test with non-invasive
equipment used to check hearing and pulse oxygen (to identify heart disease).
Thankfully, along with advances in diagnosing these conditions, progress is also being made in the development of effective treatments.
The original treatment for PKU was (and still is) dietary management. With the right advice from geneticists and metabolic dietitians and a lot of careful
attention to food intake from the family, the adverse effects of PKU can be avoided. This is not extraordinarily high-tech, but is very effective .
Many other conditions detected by newborn screening can be managed with diet and supplements or with a single medication (like thyroid hormone replacement
for patients with congenital hypothyroidism). Patients with hearing loss identified at birth may benefit from the early use of hearing aids or
cochlear implants, leading to not only better hearing, but also improved development and speech. Congenital heart defects that may have gone undetected
for months, or even years, can often be surgically corrected right away. Other disorders, like cystic fibrosis and sickle cell disease don’t have
a single treatment yet, but do have improved outcomes with early detection and comprehensive medical care.
For some of the most recent additions to our newborn screening panel, patients are unable to make a needed enzyme, so novel treatments like enzyme
replacement therapy (replacing the missing enzyme with a medication) or bone marrow transplant (introducing healthy cells that can make the missing
enzyme) are improving symptoms and quality of life. Advancing technology has made these medications and procedures available and they can be life-saving
for patients with these rare diseases.
So, how did we get to the 50+ conditions that South Carolina currently screens?
Each state determines which conditions are on their newborn screen, but all states now try to follow the national Recommended Uniform Screening Panel (RUSP) of 34 core conditions and 26 secondary conditions. Anyone can nominate a condition for the RUSP, and often this is a combination of parents/advocates
and researchers. Conditions are added to the RUSP after a committee reviews the scientific knowledge about the condition and the screening test.
The reviewers are looking for an overall benefit of screening and whether it can be practically implemented, including things like:
- The condition is a serious health issue
- Enough is known about the rare disorder to be certain about the diagnosis
- An effective treatment exists
- Screening can provide quick results
- States can provide the screening with reasonable expenses
- Most or all babies with the condition will be detected, without too many false-positive results
Not all conditions will be approved, but as we continue to better understand how these conditions can be diagnosed and treated, the list is sure to
keep growing. For example, Pompe disease was initially declined because of a few pieces of lacking evidence, but about 5 years later it was added
to the RUSP. Soon newborns in South Carolina will be screened for this condition and given the chance to receive early treatment with a synthetic
enzyme that will improve survival and quality of life.
Where are we going from here?
As new testing methodologies and treatment options become available, more and more conditions will be recommended and approved for newborn screening.
It is truly an exciting time to be in genetics, as we are in the midst of amazing research and discoveries that are not only treating patients
after symptoms develop, but with early detection, can prevent children and their families from the devastating effects of many of these conditions.
Dr. Guthrie likely couldn’t dream of the number of lives his innovation would save! The ‘PKU test’ has come a long way, and we are excited to see how
families will continue to benefit as progress continues.
By: Jennifer Stallworth, MS, CGC