Cystic fibrosis

Although mutation detection rates have not universally reached the 95% detection level recommended by the American Society of Human Genetics and are not likely to exceed 90% for many populations in the foreseeable future, CF carrier screening will probably be offered routinely in the near future. Although CF carrier information will be of benefit to some individuals and couples, the inability of conventional prenatal diagnosis to provide definitive diagnostic outcomes to some couples, specifically those couples in which only one partner has a detectable mutation, will make for considerable anguish and concern for some. Because genetic screening and counseling is meant to provide information and alleviate concerns and fears, the potential for CF screening to result in such a contradictory effect is of a continuing concern to those who provide obstetric and genetic services. In a National Institute of Health-sponsored workshop, Menutti and colleagues recommended that those populations to which carrier screening should be offered might include individuals and couples in high-risk groups (e.g., Ashkenazi Jews, central or northern Europeans, one partner with CF, and individuals with a family history of CF) who seek preconception counseling, infertility care, or prenatal care. The workshop participants concluded, however, that before screening can be offered systematically to these individuals or couples, practice guidelines, educational materials for providers and patients, informed-consent protocols, and laboratory standards for testing must be developed. Further advances in DNA and protein analytic capabilities, such as microchip analytic systems and protein truncation assays, may make CF screening and diagnosis more accurate and less likely to result in equivocal outcomes. In addition, it is hoped that continuing improvements in CF therapies will increase the life expectancy and improve the quality of life for individuals affected with CF. Expanding our current knowledge of genotype-phenotype correlations will not only allow us better to predict clinical outcomes but also may improve our treatments for individuals with CF because more targeted therapies may be developed for CF caused by specific mutations. Nonetheless, educational and counseling issues will, for the foreseeable future, remain of critical importance to ensure appropriate clinical care to low- and high-risk individuals.