PKU is a genetic disease that manifests at birth and results from an inability to break down phenylalanine (phe), an amino acid that is commonly found in many foods. Left untreated, high levels of ...

In 1957, Guthrie met Robert Warner, a specialist who diagnosed individuals with mental disabilities. Warner told Guthrie about phenylketonuria (PKU), now known to affect roughly 1 in 10,000 children.