Cystic fibrosis: causes, symptoms and therapies

Rare inherited genetic disorder that causes progressive obstruction of the air and intestinal ducts.

Cystic fibrosis, also called mucoviscidosis or fibrocystic pathology of the pancreas, is the most common among rare inherited genetic diseases; is classified as autosomal recessive and affects about 100 thousand people in the world, 6 thousand only in Italy, without distinction between males and females.

Life expectancy has increased in recent years thanks to advances in scientific research: it is now around 40 years.

What are the causes of cystic fibrosis?

It is due to the mutation of a particular gene, the CFTR (Cystic Fibrosis Transmembrane Regulator), responsible for the synthesis of a protein that regulates the transport of sodium chloride through the membrane of epithelial cells and mucous glands. Changes in concentration inside and outside these structures influence by osmosis the water content and therefore the viscosity of secretions. The mutation of this gene results in the production of mucus much thicker than normal.

Being less fluid, the mucus progressively obstructs especially the bronchi and the pancreatic duct with consequent recurrent respiratory infections and difficult digestion of food due to the blockage of the passage of pancreatic enzymes. The accumulation of mucus, in the long run, also damages the tissue and the structure of the affected organs, compromising their functionality.

The disease occurs when the child inherits a copy of the mutated CFTR gene from both parents. The parents, having only one altered copy of the gene, do not develop the disease and are therefore defined as healthy carriers. When two healthy carriers (about 1 in 25/26 in the Western world) meet, the probability of having a child with cystic fibrosis is about 1 in 4.

Symptoms

The symptomatology of cystic fibrosis is wide since it affects not only the respiratory and digestive systems, but also many other organs and therefore can manifest itself differently from person to person.

When the airways and lungs are particularly affected, the main symptoms are:

• persistent cough
• very dense sputum
• recurrent respiratory infections, including pneumonia, chronic sinusitis or bronchitis.

Respiratory failure and the appearance of asthma or swelling of the nasal ducts are also frequent. In some cases, lung collapse, called pneumothorax, or hemoptysis, or coughing up blood, may occur.

If the disease particularly affects the intestine, it goes from loss of appetite and weight loss to vitamin deficiency and pancreatic insufficiency, which causes difficulties in digestion and absorption of food. In some infants, there may also be an intestinal obstruction called meconium ileus, while in older children diarrhea may appear.

To these symptoms related to the organs generally most affected, are also associated:

• liver disorders, such as cirrhosis of the liver, following blockage of the bile ducts
• increased risk of developing diabetes
• growth retardation
• “salty taste” of the skin due to sweating richer in sodium than normal.

Cystic fibrosis also affects the reproductive system. In men, viscous secretions obstruct the vas deferens, i.e. the channels that connect the testicles with the prostate, thus determining their sterility. Women, on the other hand, retain the ability to conceive and carry the pregnancy to term, despite being less fertile than others. However, it is important to remember that during gestation the symptoms of the disease increase; It is therefore necessary to consider all the possible risks of pregnancy. In addition, sometimes the use of contraceptives such as the pill, the transvaginal ring or the transdermal patch can also cause a worsening of the clinical picture.

Diagnosis

Although the symptoms are quite clear, it is still essential to conduct a timely and correct diagnosis considering above all the early onset and rapid course of the disease.

In most cases it is identified immediately after birth through a simple blood sample to which all newborns are routinely subjected. Cystic fibrosis is in fact part of the basic newborn screening program for genetic diseases, carried out free of charge and by specialized centers through trypsin testing. If this is positive, we proceed with the sweat test.

The trypsin test involves a small blood sample from the heel of the newborn in the first 48/72 hours of life and, as the name of the exam implies, evaluates the levels of trypsin, an intestinal degradation enzyme. High trypsin levels do not necessarily indicate the presence of cystic fibrosis, so the center contacts the family for a second checkup.

The sweat test remains the best diagnostic tool, being not only effective but also painless and non-invasive since it is performed by measuring the concentration of sodium chloride in the baby’s sweat.

If this exceeds 60 mEq / L the test is considered positive and therefore cystic fibrosis is diagnosed, while it is negative if the concentration of sodium chloride is less than 40 mEq / L. If the values are in the range between 40 and 60 mEq/L it is recommended to repeat the test.

To determine the level of severity of the disease, at these first two evaluations, if positive, the doctor usually recommends further tests focused mainly on the lungs, pancreas and intestines.

If you suspect you are a healthy carrier, you can carry out the so-called “carrier test” in order to identify any mutation. It is also recommended to conduct tests to any brothers and sisters or close cousins of the patient, even if they do not manifest the disease.

Early diagnosis is generally the best weapon to contain the disease, as it allows a timely start of therapy and a prognosis as favorable as possible.

Although they account for only 10% of cases, there are also less severe forms of cystic fibrosis that occur in adulthood.

What are the therapies for cystic fibrosis?

Despite important medical discoveries, to date there is still no definitive cure for cystic fibrosis, but only symptomatic treatments aimed mainly at:

• prevent infections
• reduce the amount and consistency of secretions
• maintain an adequate nutritional and/or caloric intake
• improve breathing and, in general, the quality of life.

Among the most common drugs and care strategies we find:

• antibiotics to contain the development of lung infections although they are not to be used for long periods as it is possible to incur antibiotic resistance or other fungal infections in the oral cavity
• mucolytics to thin mucus and make it easier to expectorate
• bronchodilators, which can be taken through inhalation or nebulization with the aim of keeping the respiratory tract open at the bronchial level and thus favoring the elimination of sputum
• oral therapy with digestive enzymes to ensure proper metabolism and absorption of nutrients
• analgesics to slow structural impairment of the lungs in some children
• bronchial drainage to manually remove mucus from the lungs with repeated taps on the chest and back. This maneuver can also be performed by the patient himself and sometimes must be repeated several times a day
• lung transplantation, an operation that has become the standard treatment for patients suffering from end-stage respiratory failure and which can also benefit those suffering from cystic fibrosis. To raise awareness of organ donation, an issue often seen as taboo, the Italian League of Cystic Fibrosis onlus (Lifc) has launched the #a18annipuoi campaign.

In addition to these treatments, there are also:

• the complete exclusion of smoking, both active and passive
• good body hygiene, with particular attention to frequent hand washing to reduce the risk of bacterial contagion.

It is also important to follow a correct and regular diet adapted to the needs of the individual. Normally it is a high-calorie diet to go partly to remedy the altered absorption of nutrients and thus avoid malnutrition. It is also advisable to consume small snacks at very short intervals of time (so as not to burden digestion) to be combined if necessary with supplements of fat-soluble vitamins (A, D, E and K) and calcium. Drinking plenty of fluids helps keep mucus more fluid, especially during the summer when sweating becomes more intense.

Even moderate, but constant, exercise has positive effects not only for the disease, but also to help the child feel “equal” to his peers. A very frequent aspect in subjects affected by cystic fibrosis is in fact to consider themselves “different” and unable to lead a normal life. Sport, with the help of parents and friends, is therefore fundamental in ensuring the serenity of the patient.

It is also important to maintain good contact with the family doctor and with the center specialized in the treatment of this pathology, as well as to perform all the necessary checks at the recommended times.

Finally, another valuable help is to follow the calendar of vaccination boosters, to be integrated with those for influenza and pneumococcus because, although the disease in question does not directly affect the immune system, the child is still more likely to get sick and incur further complications.