Screening for cystic fibrosis: the practice and the debate

Cystic fibrosis is a serious disorder that has been defined on the basis of clinical description, physiological abnormality and more recently by DNA based testing. Newborn screening based upon measurement of immunoreactive trypsin with follow up by DNA testing is capable of detecting cases very often without the need of a sweat test and with the requirement for a second sample reduced to only I in 4,200 of those tested. While this efficient system avoids substantial parental anxiety, it does reveal a significant number of heterozygous parents who will require genetic counselling. There is some preliminary evidence for improved growth in the screened population; however, the main benefits of screening result from the improved efficiency of the healthcare system and reduction in the length of time required to make a diagnosis. The arguments relating to screening tor cystic fibrosis are more finely balanced than those of previous programmes such as phenylketonuria screening and the benefits of early intervention are less obvious. In addition, the potential harmful effects of unwanted genetic information are more apparent. Conclusion: On this basis while the case for screening appears justified the need to ensure properly informed consent appears even more pressing.