cystic fibrosis

cystic fibrosis
Name	Cystic Fibrosis
Caption	A chest X-ray showing characteristic hyperinflation in a patient.
Field	Pulmonology, Pediatrics, Medical genetics
Symptoms	Difficulty breathing, coughing up mucus, poor growth, fatty stool
Complications	COPD, Pancreatitis, Infertility
Onset	Childhood
Duration	Lifelong
Causes	Genetic (Autosomal recessive)
Risks	Family history
Diagnosis	Sweat test, Genetic testing
Treatment	Airway clearance therapy, Antibiotics, Pancreatic enzyme replacement therapy
Medication	Ivacaftor, Lumacaftor, Tobramycin
Prognosis	Variable (life expectancy into 40s-50s in developed nations)
Frequency	~1 in 3,000 newborns of European descent

cystic fibrosis is a life-limiting genetic disorder that primarily affects the lungs and digestive system. It is caused by mutations in the CFTR gene, which leads to the production of thick, sticky mucus that obstructs airways and ducts. The condition is inherited in an Autosomal recessive pattern, meaning an individual must inherit two defective copies of the gene, one from each parent. Management focuses on aggressive respiratory therapy, nutritional support, and, increasingly, CFTR modulator drugs that target the underlying genetic defect.

Introduction

The disease was first clinically described by Dorothy Hansine Andersen in 1938, who distinguished it from Coeliac disease. Historically, the life expectancy for individuals was very short, but advances in care have dramatically improved outcomes. The name derives from the characteristic scarring (fibrosis) and cyst formation observed in the pancreas during autopsies. Major organizations dedicated to the condition include the Cystic Fibrosis Foundation in the United States and the Cystic Fibrosis Trust in the United Kingdom, which have driven significant research and care initiatives.

Pathophysiology

The fundamental defect lies in the CFTR protein, a chloride channel found on the surface of epithelial cells in organs like the lungs, pancreas, liver, and intestines. Dysfunctional CFTR leads to impaired chloride and water transport, resulting in the production of dehydrated, viscous secretions. In the lungs, this mucus impairs cilial clearance, leading to chronic infection and inflammation by pathogens such as Pseudomonas aeruginosa and Staphylococcus aureus. Pancreatic duct obstruction causes Exocrine pancreatic insufficiency, malabsorption, and can lead to CF-related diabetes.

Diagnosis

Newborn screening programs, now widespread in countries like the United States, Canada, and Australia, initially measure levels of IRT in blood spots. A positive screen is followed by the definitive Sweat test, which measures chloride concentration in sweat, a procedure standardized by the Gibson and Cooke method. Confirmatory Genetic testing identifies mutations in the CFTR gene, with the most common being F508del. Prenatal diagnosis is available through procedures like Chorionic villus sampling for families with a known history.

Management

Treatment is multidisciplinary, involving specialists in Pulmonology, Gastroenterology, and Physiotherapy. Daily Airway clearance therapy techniques, such as chest physiotherapy and devices like the Acapella valve, are cornerstone practices. Inhaled medications include Dornase alfa to thin mucus and antibiotics like Tobramycin to combat infection. Nutritional therapy involves high-calorie diets, fat-soluble vitamins (A, D, E, K), and Pancreatic enzyme replacement therapy with products like Creon. Landmark CFTR modulator therapies include Ivacaftor (Kalydeco) and combination drugs like Lumacaftor/ivacaftor (Orkambi) and Elexacaftor/tezacaftor/ivacaftor (Trikafta).

Epidemiology

It is most common among people of Northern European ancestry, with a carrier frequency of about 1 in 25 and an incidence of approximately 1 in 3,000 live births. The incidence is lower in other populations, such as those of African or Asian origin. The World Health Organization notes significant regional variation in prevalence and access to care. Data from registries like the Cystic Fibrosis Foundation Patient Registry and the European Cystic Fibrosis Society Patient Registry are crucial for tracking outcomes and health trends.

Research

Research has been propelled by the work of the Cystic Fibrosis Foundation and collaborations with pharmaceutical companies like Vertex Pharmaceuticals. Current frontiers include next-generation CFTR modulators, Gene therapy approaches using vectors like AAV, and antisense oligonucleotides to correct specific mutations. Studies on the lung Microbiome and the role of inflammation are also active areas. The development of organoid models from patient cells, pioneered by groups like the Hubrecht Institute, allows for personalized drug testing.

Category:Genetic disorders Category:Pediatrics Category:Autosomal recessive disorders