Cystic fibrosis

Cystic fibrosis is a disease caused by defects in the expression of the CFTR protein, which is essential in certain epithelial cells of the respiratory, digestive, reproductive and sweat gland systems.

Cystic fibrosis (CF) is an autosomal recessive inherited disease that mainly damages the respiratory system and other organs such as the pancreas, intestine, liver and sweat glands. Specifically, it affects the epithelial or lining cells, which generate mucous secretions causing them to produce thicker fluids that are more difficult to expel and can eventually lead to obstruction, infection and inflammation of the bronchi or other tissues.

The disease is caused by a defect in the CFTR gene that codes for a protein involved in the transport of chloride ions and water in the epithelium.

CF is the most frequent pathology of genetic origin in the Caucasian population. It is estimated that the prevalence of CF in the general population is approximately 1 case per 9,000 inhabitants and in Europe, its incidence is one case per 2,000-3,000 births.

Symptoms

CF is a chronic, progressive disease whose symptoms usually appear after birth, although it can have a later onset, and mainly affects the respiratory and digestive systems.

Symptoms can range from moderate to severe and include:

  • Thick secretions and chronic lung infections.
  • Pulmonary fibrosis.
  • Malabsorption in the gastrointestinal system caused by obstruction of the pancreatic and biliary canaliculi.
  • Lipid intolerance and weight loss, as bile salts and pancreatic enzymes essential for lipid absorption in the duodenum are not released.
  • Diarrhea
  • Short stature
  • Diabetes associated with CF
  • Biliary cirrhosis
  • Hepatomegaly or enlargement of the liver
  • Infertility in males

Disease management

Treatments are aimed at improving patients' quality of life and focus on increasing airway mucosal clearance, controlling infections and correcting nutritional deficits. Thanks to advances in the therapies used, the life expectancy of CF patients has been extended to over 40 years.

Drugs have been designed to improve lung function in CF patients. The first to be developed was Ivacaftor, which acts as a CFTR enhancer and is used in patients with a certain type of CFTR mutation. In some cases (homozygotes for F508del), Ivacaftor can be combined with other drugs such as Lumacaftor and other second-generation CFTR modulators, such as Tezacaftor, which in addition to being effective in the prevention of CF complications have fewer adverse effects.

Genes analyzed

CFTR

Bibliography

Bienvenu T, Lopez M, Girodon E. Molecular Diagnosis and Genetic Counseling of Cystic Fibrosis and Related Disorders: New Challenges. Genes (Basel). 2020 Jun 4;11(6):619.

Cutting GR. Cystic fibrosis genetics: from molecular understanding to clinical application. Nat Rev Genet. 2015 Jan;16(1):45-56.

Fonseca C, Bicker J, Alves G, Falcão A, Fortuna A. Cystic fibrosis: Physiopathology and the latest pharmacological treatments. Pharmacol Res. 2020 Dec;162:105267.

Hanssens LS, Duchateau J, Casimir GJ. CFTR Protein: Not Just a Chloride Channel? Cells. 2021 Oct 22;10(11):2844.

Savant A, Lyman B, Bojanowski C, Upadia J . Cystic Fibrosis. 2001 Mar 26 [updated 2022 Nov 10]. In: Adam MP, Everman DB, Mirzaa GM, Pagon RA, Wallace SE, Bean LJH, Gripp KW, Amemiya A, editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2023.

Sosnay PR, Siklosi KR, Van Goor F, et al . Defining the disease liability of variants in the cystic fibrosis transmembrane conductance regulator gene. Nat Genet. 2013 Oct;45(10):1160-7.

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