How is Cystic Fibrosis inherited?

CF is an autosomal recessive condition, which means that both copies of the gene need to be altered to result in the condition.
It is only when two carriers have a child that has inherited both altered CFTR genes (one from each parent) that CF occurs. If both parents carry an altered gene, they have 1 in 4 (25%) risk of having a child affected with CF in each pregnancy they have together.