Cystic fibrosis

Cystic fibrosis, also known as mucoviscidosis, is one of the most common genetic disorders in white people of Northern European ancestry.

It affects the body’s secretory glands, leading to damage in organs such as the lungs, pancreas, liver, and digestive and reproductive systems.

People with cystic fibrosis produce thick, sticky mucus, which clogs the airways and digestive tract, making it difficult to breathe and to properly absorb nutrients from food.

Cystic fibrosis is caused by mutations in the CFTR (cystic fibrosis transmembrane conductance regulator) gene, located on chromosome 7 (7q31.2).

The disease is inherited in an autosomal recessive pattern, which means a person must inherit the altered gene from both parents to have the disorder.

Carriers (individuals with only one altered gene) do not have the disease but can pass the altered gene to their children.

If both parents are carriers of a defective CFTR gene, each pregnancy has a 1 in 4 chance (25%) of resulting in a child with cystic fibrosis (if the child inherits the defective gene from both parents).

Approximately one in every 2,500 children is born with cystic fibrosis, and it is estimated that about one in 25 people carry the defective gene responsible for the disorder.

Cystic fibrosis presents with various clinical symptoms at different life stages, leading to a wide range of manifestations.

Depending on age, the disease is commonly associated with certain characteristic symptoms:

• Infants:
  • Recurrent respiratory infections
  • Dehydration
  • Hyponatremia and hypochloremia (low sodium and chloride levels)
  • Meconium ileus (intestinal blockage in newborns)
  • Pancreatic insufficiency
  • Rectal prolapse
• Children:
  • Allergic bronchopulmonary aspergillosis
  • Sinusitis
  • Nasal polyposis
  • Distal intestinal obstruction syndrome
  • Fatty liver (hepatic steatosis)
  • Kidney stones
• Adolescents and adults:
  • Hemoptysis (coughing up blood)
  • Pneumothorax (collapsed lung)
  • Respiratory failure
  • Intussusception (intestinal folding)
  • Bile duct fibrosis and cirrhosis
  • Digestive cancers
  • Delayed puberty
  • Osteoporosis
  • Kidney failure
  • Arthritis
  • Vasculitis

The diagnosis of cystic fibrosis is based on the presence of at least one of the following three criteria:

1. Respiratory, gastrointestinal, or urinary symptoms typical of the disease.
2. A sibling with a confirmed diagnosis of cystic fibrosis.
3. A positive result from newborn screening tests (part of routine neonatal screening).

In addition, at least one of the following findings must be present to confirm the diagnosis:

• Evidence of CFTR dysfunction, such as elevated sweat chloride concentrations confirmed by a sweat test (iontophoresis). People with cystic fibrosis secrete excessive salt in their sweat.
• Identification of two CFTR gene mutations through genetic testing on a blood sample.
• Abnormal nasal potential difference: This test is conducted when there is high suspicion of cystic fibrosis, but results from the sweat test or genetic tests are inconclusive. Electrodes are placed on the nose and forearm to measure electrical potential differences, which can indicate insufficient CFTR function if abnormal.

Additional tests are performed to assess the function of affected organs and monitor for potential complications. These may include:

• Pancreatic function tests.
• Lung imaging, such as X-rays and CT scans.
• Microbiological analysis to detect infections such as Haemophilus influenzae, Staphylococcus aureus, and Pseudomonas aeruginosa, especially in young children who are prone to severe and frequent infections.
• Lung function tests.
• Kidney function tests.

Currently, there is no cure for cystic fibrosis. However, advances in treatment have helped patients better manage symptoms, significantly improving life expectancy. Many people with cystic fibrosis now reach adulthood and can often enjoy an active and nearly normal life.

The future of cystic fibrosis treatment may lie in gene therapy, which aims to replace the defective gene with a functional one.

The main treatments are:

• Treatment for respiratory system involvement: Excessively thick mucus can obstruct the bronchi, leading to respiratory failure and repeated infections that damage lung tissue. Treatments typically include antibiotics (oral, nebulized, or intravenous), respiratory physiotherapy, and regular physical exercise to help keep the lungs as clear as possible. Nebulized DNase and hypertonic saline are also used to reduce mucus viscosity. In severe cases, a lung transplant may be necessary.
• Treatment for digestive system involvement: In cystic fibrosis, pancreatic enzyme flow to the duodenum is often blocked, resulting in poor absorption of proteins, carbohydrates, and fats, which causes digestive disorders, abdominal pain, and bloating. This leads to weight loss, malnutrition, and impaired growth. Treatment often includes pancreatic enzyme supplements, dietary supplements, and vitamin complexes. Liver issues, intestinal complications, and cystic fibrosis-related diabetes may also arise and are treated accordingly.
• Treatment for sweat gland involvement: People with cystic fibrosis lose excessive salt in their sweat, so they must take precautions in hot weather, during intense physical activity, or during fever. It is essential to stay hydrated, and salt supplements may be necessary.

Cystic fibrosis treatment requires a multidisciplinary team, including pediatricians, pulmonologists, gastroenterologists, cardiologists, microbiologists, dietitians, physiotherapists, psychologists, social workers, nurses, and support staff. Each specialist plays an important role in managing cystic fibrosis.

In many places, cystic fibrosis care is provided in specialized reference centers, which enable personalized monitoring and follow-up.

Family support is crucial, helping the patient maintain a sense of normalcy and responsibility regarding their treatment. Parent associations also play an important role in offering support and resources.