Frequency of detection of carrier partners

The risk of having a child with cystic fibrosis (CF) is reduced, but not eliminated, when both members of the couple are tested and no CF mutations are identified. This table shows the proportion of high-risk couples (couples in which each member carries a CF gene) that are correctly identified according to the percentage of CF cases accounted for by the mutations in the screening panel. If each member of the couple is tested only for F508del-CFTR, which accounts for 75 percent of all CF cases, 56 percent of couples who are truly at risk of having a child with CF will be correctly identified; if each member is tested for mutations that account for 90 percent of all CF cases (the screening panel that is most commonly used), 81 percent of at-risk couples will be correctly identified.