[Epidemiological data. Neonatal and prenatal screening].

Unlike what is generally thought, cystic fibrosis is not the most frequent hereditary disease. Its frequency is approximately 1/3 200 and varies with the geographic area. The frequency of heterozygous subjects is about 1/28. No country has established a generalized neonatal screening programme, for technical reasons and because there has been no demonstration of a beneficial effect from early care. It would nevertheless be useful to develop experimental programmes defining which protocols might best be established. Antenatal screening can be based on detecting heterozygous subjects, a technically feasible operation, although answers to a large number of questions would be required.