1 Department of Pediatrics, Johns Hopkins Hospital, Baltimore, MD 21205
In Reply.
Our estimate that 16% of infants with phenylketonuria (PKU) could be missed by screening on the first day of age was not based on the data that Schoen claims, but on phenylalanine determinations in newborn siblings of known phenylketonurics, each of whom proved to have PKU.1 Reports of the phenylalanine concentrations in additional newborn siblings with PKU2,3 constitute (with the exception of Sepe et al,4 discussed below) the "heavy criticism" alluded to by Schoen.