Cystic fibrosis is the most common lethal autosomal recessive disease among Caucasians. Its incidence is 1:3,200 among Caucasians, 1:10,000 among Latinos, and 1:10,500 among African Americans. It results from mutations in the CFTR gene, which regulates ion transport across the cell membrane, leading to abnormally thick and stringy secretions that obstruct the airways. Typical symptoms include digestive manifestations (recurring pancreatitis, pancreatic failure, intestinal obstruction, and malnutrition), pulmonary manifestations with recurring pulmonary infections, bronchiectasis and decline of the pulmonary function, growth retardation, and male infertility.
The diagnosis of CF requires that both internationally accepted diagnosis criteria are met:
- Symptoms concordant with CF in one or more organs or positive result in neonatal screening tests or sibling with a cystic fibrosis diagnosis.
- CFTR gene dysfunction evidenced by an increase in the concentration of chlorine in sweat >60mmol/L or alteration in the nasal transmembrane potential or presence of two mutations related with CF in each of the gene’s alleles.
In addition to its implications for the diagnostic process, family study, and prenatal genetic counselling, testing for mutations in the CFTR gene is crucial for therapeutic decision-making because new CFTR modulators are indicated for patients with specific variants.