Cystic Fibrosis is a genetic disorder. All genes come in pairs, so everyone has two copies of each gene. One copy comes from your mother and the other from your father. Some genes do not function properly because there is a mistake in them. If a gene has a mistake, it is said to be altered or changed. For some diseases-like CF- both genes of the pair have to be altered for a person to have the disease.

If a person has one changed copy of a CF gene, that person is a carrier for CF. A carrier does not have CF. There is no known health problems associated with being a carrier of CF. If a person has two changed copies of the CF gene, they will develop CF.

When both partners in a couple are carriers, any child they have has a l in 4 (25%) chance to inherit a changed copy of the gene from each parent. A child with two changed copies of the CF gene will develop CF.