Le dépistage néonatal généralisé par des tests d'analyse biologique

Abstract

Implementation of a generalized screening program for neonatal diseases obeys precise guidelines. The disease must be severe, recognizable at an early stage, accessible to an effective treatment, detected with a non expansive and widely applicable test and it must represent an important health problem. In case of positive results, treatment or prevention shall be offered immediately and any screening program has to be regularly evaluated. There is in France since 1978 a national screening program that depends on a private association (“Association française pour le dépistage et la prévention des handicaps de l'enfant”) and is supervised by the “Caisse nationale d'assurance maladie” and the “Direction Générale de la Sante”. Presently, five diseases are included in the screening program: phenylketonuria, hypothyroidism, congenital adrenal hyperplasia, cystic fibrosis and sickle cell disease, the latter only in at risk newborns. Toxoplasmosis represents a particular problem because screening takes place only in children of mothers that have not been controlled during their pregnancy or in case of seroconversion. Neonatal screening of phenylketonuria and hypothyrodism is unanimously recommended. That of congenital adrenal hyperplasia is approved in most countries. The cases of sickle cell disease and cystic fibrosis are more complex because: 1) all the children that carry the mutations are not affected with a severe disease; 2) there is no curative treatment; 3) parents given information are made anxious, sometimes wrongly if the disease is mild or asymptomatic. The supporters of the screening insist on the interest of an early diagnosis which makes longer the life time of these children, the possibility for the parents to utilize prenatal screening in case of a future pregnancy, and the information given to the heterozygous carriers following a familial screening. The question is raised of the extension of neonatal screening to other diseases. This is now possible due to technical progresses such as the tandem mass spectrometry that can detect about 50 diseases in an only testing. In addition of its cost and of the difficulty to ensure an efficient organization, increasing the number of the screened diseases will raise ethical problems including how the parents will be informed of an incurable disease or a late-onset disease or an entirely asymptomatic disease. It is unanimously admitted that only mendelian diseases should be detected excluding genetic polymorphisms. Analysis of the present situation suggests the following developments: 1) to actualize the guidelines for deciding of a new neonatal screening; 2) to experiment on a local scale any new screening before its extension to the whole country; 3) to create an evaluation committee including paediatricians and epidemiologists and to evaluate on the long term the future of the children; 4) to precisely define the conditions in which the heterozygous carriers will be informed following a familial investigation; 5) to store in a resource biological centre the blood samples in order to utilize this bank for epidemiology studies.