Neonatal screening for cystic fibrosis in Brittany, France: assessment of 10 years' experience and impact on prenatal diagnosis

Background Neonatal screening for cystic fibrosis has been a subject of deb ate over the past few years. This study assesses 10 years of neonatal scree ning in Brittany, France, and examines its impact on prenatal screening of subsequent pregnancies in couples with an affected child. Methods The study included all the neonates screened for cystic fibrosis in Brittany from Jan 1, 1989, to Dec 31, 1998. The screening consisted of an immunoreactive trypsinogen assay from dried blood spots, plus, from 1993, m utation analysis. Data were collected on incidence of cystic fibrosis, and genotypic and biochemical characteristics. The use of prenatal screening of subsequent pregnancies in affected families was also investigated. Findings Of the 343 756 neonates screened, 118 children with cystic fibrosi s were identified, giving an incidence of one in 2913. All mutated alleles were characterised: 34 different mutations resulting in 36 genotypes were d etected, The introduction of DNA analysis into the protocol greatly reduced the recall rate and increased the sensitivity of the test. The mean cost o f the screening programme was US$2.32 per screened child. 39 (34%) of the f amilies identified by neonatal screening opted for subsequent prenatal diag nosis at least once. 12 couples would have benefited from this procedure wh ile their first child was still symptom-free. 42 healthy children were born , and 18 pregnancies were terminated (therapeutic abortion rate of 100%). Interpretation We have shown the feasibility of neonatal screening for cyst ic fibrosis in Brittany. Through the detection of a large range of mutation s, neonatal screening provides the opportunity for more reliable prenatal d iagnosis and cascade screening. The neonatal screening programme described here could provide a good model for other countries intending to initiate s uch a scheme.