Routine neonatal screening for phenylketonuria in the United Kingdom 1964-78. Medical Research Council Steering Committee for the MRC/DHSS Phenylketonuria Register.

From 1964 to 1968, despite a general policy of routine neonatal screening for phenylketonuria that was usually carried out using the Phenistix nappy test, half to one-quarter of all cases reported to the register had been missed in the screening programme and had not been detected before the age of 4 months. In about two-thirds of the "missed" cases no screening test had been carried out, and in one-third a urine test had been performed but had given a false-negative result. In 1968-9 the screening programme was reorganised according to recommendations made in a Government circular (HM (69) 72), which proposed that a specimen of blood should be obtained by heel prick from all newborn infants between the 6th and 14th day of life and be tested in a central laboratory for the presence of raised blood phenylalanine concentrations. The senior medical officers of the various regions were made responsible for ensuring that all infants were tested. By 1974 only 1 to 2% of surviving infants were not being tested for phenylketonuria in the neonatal period, and only five of the 357 cases born between 1974 and 1978 and notified to the register had been diagnosed after the age of 3 months.