For someone to have CF, their parents have to each carry one copy of the gene which causes it. My husband and I each are carriers of the delta f508 gene. There are thousands of other mutations, delta f508 is one of the most common.
It's also referred to as homozygous delta f508 -- homozygous meaning two copies.
Our son was born with meconium illeus -- bowel obstruction, etc. Is pancreatic insufficient and therefore requires digestive enzymes with most foods.