Neonatal screening and long-term follow-up of phenylketonuria: the French database

In France, neonatal screening of phenylketonuria (PKU) started in 1966. A national association was created in 1978 in order to organise the neonatal screening program and to control the efficacy of the screening and patients' follow-up.

To evaluate the results of the French PKU screening program in terms of hyperphenylalaninaemia epidemiology, efficacy of the screening procedure, management and outcome of the patients.

The national database has been filled-up first with the answers to questionnaires that were sent each year by the PKU patients' physicians, and second with the results of an additional inquiry, which was set up in 1994 in order to investigate diagnosis, treatment, and school outcome of all French PKU patients.

PKU was diagnosed in 81.6% of patients with hyperphenylalaninaemia (HPA), non-PKU HPA in 17.2% and cofactor deficiency in 1.1%. From 1980, incidence of PKU has been stable: 1 per 17,124 live births. Sensitivity of the screening procedure was 99.3%. Age at diet initiation regularly decreased to reach 14 days as a median in 1996. Until 1990, median age at diet discontinuation was 6 years of age. Later, strict diet was continued longer (at least, up to 8-10 years). PKU patients who entered to secondary school at normal age were characterised by an earlier age at diagnosis and at diet initiation and a later age at diet discontinuation, compared to those who entered 1 year or more behind normal age.

These data confirm the benefit of a nationwide organised screening program. They emphasise the importance of an early neonatal diagnosis and diet initiation in PKU patients and are consistent with the benefit of a longer period of strict diet in childhood.