Adverse medical outcomes of early newborn screening programs for phenylketonuria

Despite the success of current newborn screening programs, some critics have argued that in the 1960s hundreds of children with false-positive results for phenylketonuria suffered death or disability from treatment with restrictive diets. Medically adverse outcomes after false-positive results may be a reason to be cautious when expanding current newborn screening programs. We sought to determine if newborn screening programs for phenylketonuria before 1980 led to adverse medical outcomes in children with false-positive results.

We examined the history of newborn screening programs for phenylketonuria in the United States. We reviewed the historical scholarship, conducted a systematic search for medical adverse outcomes, and interviewed key participants in the history of newborn screening programs.

We found no population-based studies of early screening programs for phenylketonuria. One author reported 2 infants treated with restrictive diets after false-positive results for phenylketonuria who were developmentally delayed, and there is unpublished evidence of 4 additional cases of inappropriate treatment, although adverse outcomes were not documented. There were also 4 published reports of adverse medical outcomes after treating children with phenylketonuria variants, as screening for phenylketonuria revealed infants with intermediate or transiently high levels of phenylalanine.

We found little evidence of death or disability that resulted from the inappropriate treatment of well children who were falsely identified by early newborn screening programs. Because the first decade of newborn screening typically reveals diagnostic and therapeutic complexity, systematic follow-up of screened populations and rapid dissemination of results may reduce morbidity/mortality rates.