Over 1,800 mutations have been described within the CFTR gene. These mutations can be readily detected using PCR and DNA sequencing technologies. Prenatal genetic testing is available to identify 'carriers', and thus detect the risk of CFTR-related disorders.

If a pregnant mother was tested and tested negative for any known disease-causing CFTR mutations, can it be assumed that the child born will be wild-type with respect to the CFTRphenotype? Explain.

a. No. If the father is a carrier and passes along a mutant allele to the child, the child will develop cystic fibrosis.
b. It depends on the genotype of the father.
c. Yes. Since this is a recessive disorder, even if the father is a carrier, the mother will contribute a wt allele, ensuring the child is wt.