As humans, we have two copies of every gene. We inherit one copy from our mother and one copy from our father. CF carriers have one copy of a CF mutation and one copy of a normal, functional CF gene.
Carriers do not have CF, but if they have a child with another carrier, there is a chance -- 1 in 4 (or 25%) -- that the child will inherit both of the genetic changes that cause CF.
Over 10 million people in the United States are CF carriers, and most do not know it. If someone is a carrier or has a family member with CF, other family members are at increased risk for carrying the same genetic changes.
Who Is At Risk for Being a CF Carrier?
Some ethnic groups have higher CF carrier rates than others. To learn more about why some ethnic groups have increased risks for certain genetic mutations, read more about the Founder Effect and Beneficial Mutation Theory.
The table below shows the risks, based on broad ethnic groups in the United States, for carrying one CF mutation.
| Ethnicity | Carrier Risk |
| Caucasian (white, European ancestry) | 1 in 25 |
| Ashkenazi Jewish | 1 in 25 |
| Hispanic | 1 in 46 |
| African American | 1 in 65 |
| Asian | 1 in 90 |
Since many people are of mixed ancestry in the United States, it can be difficult to give exact risks based on race and ethnicity. In addition, some smaller groups have not had extensive studies, so the risks of being a carrier are not yet clear.
For this reason, the American College of Obstetrics and Gynecology and the American College of Medical Genetics recommend that CF carrier screening should be offered to all individuals who are pregnant or planning a pregnancy, and all those of Caucasian ancestry.
