Sometimes known as a “PKU test,” a genetic screening for newborns actually checks for a wide range of genetic disorders.

Published: October 1, 2021 | Updated: March 1, 2023

Sometimes known as a “PKU test,” a genetic screening for newborns actually checks for a wide range of genetic disorders.

PKU, an abbreviation for phenylketonuria, is a rare inherited disorder that causes the phenylalanine amino acid to build up in the body and can lead to brain damage. It’s caused by a genetic defect that leads to a shortage of the enzyme that normally breaks down the amino acid.

As with many genetic disorders, a baby with PKU can avoid long-term health implications if the condition is addressed before symptoms develop. In the case of PKU, a special diet can start right away to prevent long-term issues.

Newborn metabolic screening tests and results typically are completed by about 7 days of age in Kentucky. In Kentucky and many other states, newborn screenings look for PKU and more than 50 other conditions, including congenital hypothyroidism, galactosemia and other inborn errors of metabolism, sickle cell disease, hearing loss, congenital heart anomalies, immunological disorders and neuromuscular disorders.

“Newborn screenings often allow children to get a jump-start on treatment that can slow the condition’s progress or allow for potentially lifesaving interventions shortly after birth,” said Kelly Jackson, M.S., CGC, a genetic counselor and manager of genetic services at Norton Children’s Genetics Center, affiliated with the UofL School of Medicine and an assistant professor of pediatrics at the UofL School of Medicine.

Spinal muscular atrophy is an example of a progressive disease that can be stopped with a new gene therapy following an early diagnosis before symptoms start. SMA affects the part of the nervous system responsible for carrying signals from the spinal cord to muscles.

Blood samples — usually from a small prick in the child’s heel — are taken shortly after birth. The sample is tested by the state lab, and if a child from the western half of the Kentucky is identified with a genetic abnormality, Norton Children’s Genetics Center is notified. The Norton Children’s Genetics Center has seven locations across the region.

Genetics counselors and other providers at the Norton Children’s Genetics Center will contact the family’s primary care physician and notify appropriate subspecialist physicians. Since a screening is not a diagnosis, additional testing will be conducted.

Some disorders can be so dangerous that treatment could begin even before the diagnostic confirmation. Other conditions begin treatment after a diagnosis is confirmed.