[Generalized neonatal screening based on laboratory tests].

Implementation of a generalized screening program for neonatal diseases must obey precise rules. The disease must be severe, recognizable at an early stage, amenable to an effective treatment, detectable with a non expensive and widely applicable test; it must also be a significant public health problem. Subjects with positive results must be offered immediate treatment or prevention. All screening programs must be regularly evaluated. In France, since 1978, a national screening program has been organized by a private association ("Association française pour le dépistage et la prévention des handicaps de l'enfant") and supervised by the "Caisse nationale d'assurance maladie" and "Direction Générale de la Sante". Five diseases are now included in the screening program: phenylketonuria, hypothyroidism, congenital adrenal hyperplasia, cystic fibrosis and sickle cell disease (the latter only in at-risk newborns). Toxoplasmosis is a particular problem because only the children of mothers who were not tested during the pregnancy or who seroconverted are screened. Neonatal screening for phenylketonuria and hypothyrodism is unanimously recommended. Screening for congenital adrenal hyperplasia is approved in most countries. Cases of sickle cell disease and cystic fibrosis are more complex because--not all children who carry the mutations develop severe forms;--there is no curative treatment;--parents may become anxious, even though the phenotype is sometimes mild or even asymptomatic. Supporters of screening stress the benefits of early diagnosis (which extends the life expectancy of these children, particularly in the case of sickle cell disease), the fact that it opens up the possibility of prenatal screening of future pregnancies, and the utility of informing heterozygous carriers identified by familial screening. Neonatal screening for other diseases is under discussion. Indeed, technical advances such as tandem mass spectrometry make it possible to detect about 50 diseases in a single run. In addition to issues of cost and organization, any increase in the number of screened diseases will raise ethical problems, such as how to inform parents of an incurable disease, a late-onset disease, or an entirely asymptomatic disorder. It is unanimously agreed that only Mendelian diseases should be screened for (excluding genetic polymorphisms). Analysis of the present situation suggests the following changes:--guidelines for choosing new diseases for neonatal screening should be updated;--all new screening programs should be tested locally before nationwide implementation;--an evaluation committee of paediatricians and epidemiologists should be created, and the children's long-term outcome should be studied;--the conditions in which heterozygous carriers are informed after familial investigations need to be precisely defined;--blood samples should be banked for epidemiological studies.