PATHOLOGY

Detailed explanation-1: -Cystic fibrosis is an example of a recessive disease. That means a person must have a mutation in both copies of the CFTR gene to have CF. If someone has a mutation in only one copy of the CFTR gene and the other copy is normal, he or she does not have CF and is a CF carrier.

Detailed explanation-2: -Cystic fibrosis is a genetic disease. People with CF have inherited two copies of the defective CF gene-one copy from each parent. Both parents must have at least one copy of the defective gene. People with only one copy of the defective CF gene are called carriers, but they do not have the disease.

Detailed explanation-3: -If both parents are carriers there is a 1 in 4 (25 percent) chance that both will pass on the non-functioning gene, which would result in a pregnancy affected with cystic fibrosis.

Detailed explanation-4: -Cystic Fibrosis People with one normal copy of the CF allele are unaffected by CF, because they can produce enough CFTR to allow their cells to work properly. Two copies of the defective allele are needed to produce the disorder, which means the CF allele is recessive.