PKU Test: Preventing Intellectual Disabilities

PKU test administered to infant.
Inspired by his mentally disabled son, Robert Guthrie simplified the method for screening infants for PKU.

Inspired by his mentally disabled son, Robert Guthrie, MD, PhD, became a tireless advocate for individuals with intellectual handicaps. He devoted much of his career to researching the prevention of mental and developmental disabilities.

To that end, the longtime UB professor of microbiology and pediatrics set out to produce a simpler method for screening infants for phenylketonuria (PKU), a genetic disorder characterized by an inability of the body to break down the amino acid phenylalanine.

Recognizing that the earlier treatment begins for PKU, the better the prognosis for intellectual growth, he developed a way to collect discs of whole blood from infants: sticking the baby’s heel and blotting the emerging drops of blood with filter paper.

The first screening took place in 1961 in Jamestown, New York. With funding from the Maternal and Child Health Division of the U.S. Children’s Bureau, Guthrie then launched a widespread testing initiative.

“We rented a house next to Children’s Hospital [of Buffalo] and established a little factory to prepare materials for testing one million infants,” said Guthrie. “Our goal was to package the test so that everything would be instant—like instant coffee. In that way, the laboratories testing for PKU would not have to employ trained bacteriologists, but could easily mix the ingredients and perform the test with existing personnel.”

Guthrie, who died in 1995, declined to patent his test or accept royalties from its sales, which allowed hospitals to quickly and inexpensively implement PKU screening on a large scale.

In time, the filter test—which is estimated to have spared 300,000 children from the effects of mental disabilities—came to be used by all 50 states to screen for PKU.

Furthermore, Guthrie’s dried-blood spot testing method spread to almost every field involving blood collection and has made possible the multiple newborn screening routinely conducted today.