The conclusions which must be drawn from the data on early detection of phenylketonuria (PKU) reported by Berry et al in The Journal of Aug 24, 1964 (189:641), are different from those reported by Allen and Wilson in The Journal of May 25, 1964 (188:720). On the basis of three phenylketonuric patients who had positive ferric chloride tests in the first eight days of life (and seven others aged 17 to 54 days with positive tests) Allen challenged the accepted view that the ferric chloride test is not of great value in early infancy. An editorial in The Journal (188:748 [May 25] 1964) commenting on Allen's paper stated, "It is recommended that a positive blood test should always be followed by a urine test, and treatment should not be initiated until the urine test becomes positive...."
Berry et al tested 17 newborn sibs of known phenylketonurics. Of
Efron ML, MacCready RA. Phenylketonuric Families. JAMA. 1965;191(5):391-392. doi:10.1001/jama.1965.03080050037010