Neonatal screening for cystic fibrosis: present and future.

Despite there being effective tests for detecting cystic fibrosis (CF) using newborn screening blood samples, screening in neonates has not had universal approval because of uncertainty about its benefits. After up to 18 y experience, at a recent conference in Caen several aspects attracted universal agreement. There is still major delay in clinical diagnosis after the onset of symptoms. There is short-term benefit in early diagnosis by screening, with reduced morbidity in the first 2 y, evidence of significant nutritional benefits up to the age of 10 y, and probable respiratory benefit over this time frame. There is great potential for research into treatment modalities and no evidence of significant psychological harm to CF babies from early diagnosis. With a screening protocol that includes a DNA test there is some unwanted carrier detection and careful genetic counselling is needed. There is no evidence yet that screening will extend the life of CF patients, so some doubts remain as to its overall effectiveness, and there have been no good studies on comparative costs in screened and unscreened cohorts. Even so, the weight of evidence suggests very worthwhile advantages for screened babies and their families. Because of this, it is unlikely that further trials will take place. It may be that the onus now is on those who do not support screening to justify this stance to parents who may favour it.