As the twins got older, their mother was diagnosed with cystic fibrosis. Mom took the test to find
out if she carried the mutated cystic fibrosis gene (CFTR). The test came back positive. Normally, the CFTR gene regulates mucus clearance from the respiratory tract. But some mutations in the CFTR genes prevent this clearance and mucus builds up in aireways making it hard to breathe. Everyone has two copies of the CFTR gene, one copy inherited from their mother and one from their father. The CFTR gene follows a pattern complete dominance.
F= No cystic fibrosis (DOMINANT)
f= Cystic fibrosis (RECESSIVE)
What is the phenotype of an individual with the genotype Ff?