Toward a Realistic Assessment of PKU Screening

Newborn screening for the genetic disease phenylketonuria (PKU) is generally considered the greatest success story of applied human genetics. Even those generally skeptical of the value of genetic testing often comment enthusiastically on this program. In fact, PKU screening has been plagued with serious problems since its inception in the early 1960s. This essay describes some of these difficulties and asks what lessons they hold for other screening programs. It also argues that realism in our assessment of such programs requires that we pay greater attention to the concrete experience of families. How screening should work in theory is of less importance than how it does work in practice.