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What is cystic fibrosis?

The life expectancy of cystic fibrosis patients has increased notably thanks to advances in treatments, aiming to reduce the complications of this serious inherited disease.

Cystic fibrosis is a condition where there is an alteration in the concentration of sodium chloride (salt) in essential secretions of sweat, mucus, and gastric juices, disrupting the function of these organs where they occur and leads to fibrosis and formation of cysts in the pancreas as part of a self – destructive phenomenon, and infections chronic lung by altering defenses.

Cystic fibrosis is a genetic disease due to a series of mutations in the gene that encodes CFTR (cystic fibrosis transmembrane conductance regulator), a protein responsible for regulating chlorine transport through the membrane of epithelial cells. Exocrine (such as sweat glands). The alteration of CFTR affects the regulation of the organism’s chlorine channels, causing a decrease in water secretion, and consequently an increase in the viscosity of secretions., which are thus more difficult to eliminate, obstructing the ducts of the organs that have altered epithelial cells, such as the pancreas, the lung, the intestine, and the sex glands. The most affected are the sweat glands, which leads to an increase in the salt content of sweat, which is the data that allows establishing the diagnosis of cystic fibrosis.

The Role of Heredity in Cystic Fibrosis

Cystic fibrosis is a hereditary disease in the white race, affecting one in every 2,000 live births of this race, while the percentage is reduced to one in 17,000 live births of the black race. Patients have a risk of having a sick child of 1% (which is much higher than expected in the rest of the population). The disease is transmitted in a recessive autonomic way, which means that an affected child has his parents as healthy carriers, and the risk that his offspring suffer from the disease is 25%. There are 5% of people who have the own gene for the disease but who, nevertheless, are healthy and have not developed the pathology.

Years ago, cystic fibrosis was a disease confined to childhood due to the short life expectancy of people born with the condition. However, patients’ life expectancy has increased notably, mainly due to the progress achieved in treatments (especially respiratory infections and nutritional status). From a 2014 report by the Cystic Fibrosis Foundation, a mean life expectancy is estimated to be around 39 years.

Also, there are patients who, probably due to an alteration of the genes involved, have milder symptoms, which is why they are diagnosed later (at puberty or even in adulthood). In populations where initially this disease was not frequent or was not known, there is currently an increase in the incidence, probably due to further development of detection methods and an improvement in techniques to diagnose atypical or milder forms of cystic fibrosis.

Causes of cystic fibrosis

Cystic fibrosis is a genetic disease caused by a series of mutations in the gene encoding a protein called transmembrane conductance regulator cystic fibrosis (CFTR). The CFTR is in charge of regulating chlorine transport through the membrane of exocrine epithelial cells (such as sweat glands). When CFTR is altered, there is a disorder in regulating the organism’s chloride channels, which causes a decrease in water secretion, which increases the viscosity of the secretions, which are thus more difficult to treat. Eliminate, and produce an obstruction of the ducts of the organs that have altered epithelial cells, such as the lung, pancreas, intestine, and sex glands.

The sweat glands are the most affected, leading to an increase in the salt content of sweat; This information allows the diagnosis of cystic fibrosis to be established.

Likewise, the gene mutation for this protein alters the different local defense mechanisms of some affected organs, such as the lung. For example, lysozyme and lactoferrin, which are found naturally in the airways and have some antibacterial power, are altered if the sodium chloride concentration is high due to cystic fibrosis. Thus, there is a greater vulnerability for infections in these people.

The activity of the microscopic cilia or hairs found in the mucosa of the respiratory tract and which has a defensive purpose and the elimination of mucus also appears to be altered for the same reason. This function is altered as well.

It is postulated that in the pancreas, the alteration in chlorine concentration, sodium, and bicarbonate thickens the secretion generated in this viscera, progressively obstructing and self-destructing it.

And finally, the CFTR gene mutation is the cause of the plugging of the vas deferens due to the same alteration described, causing the male sterility that usually accompanies these patients.

Cystic fibrosis symptoms

Cystic fibrosis is a disease that affects various organs, mainly the digestive, respiratory, and reproductive systems. Learn in more detail about the symptoms of cystic fibrosis that affect each of these body systems:

Manifestations and symptoms of cystic fibrosis affecting the digestive system

Cystic fibrosis can alter all digestive organs that have a secretory function, that is, that produce some substance, such as the pancreas, affecting exocrine function (release of hormones that intervene in the process of digestion), and less endocrine (which is involved in the release of insulin).

The intestinal affection can be manifested from birth by meconium ileus (intestinal obstruction caused by the increased viscosity of intestinal secretions). This is due to a decrease in the intestinal content’s fluidity due to the decrease in the amount of water it contains. There is also a reduction in the release of pancreatic enzymes that, under normal conditions, are responsible for digesting and making the meconium more liquid (the baby’s first stools ) to facilitate its expulsion. The clinic, therefore, is characterized by pain and increase in the abdomen, vomiting, and absence of meconium stools, during the first days of life (that is, the child does not have a bowel movement in these first days after birth when the normal thing is that after 24-48 hours he/she would have already had a bowel movement / is).

Equivalent meconium syndrome

This intestinal involvement is due to an increase in intestinal content consistency, usually associated with a slowing down of intestinal transit. Its prevalence is highly variable, less than 2% in children under 5 years of age and between 7 and 12% in patients between 5 and 30 years of age. The clinic is usually based on severe abdominal pain, which appears before the intestinal obstruction (several weeks or months before). Constipation is also common, although in some cases, there may be diarrhea.

Pancreatic involvement

It is present in 90% of patients with cystic fibrosis (practically all have evidence of pancreatic insufficiency, but 10% have respected pancreatic function).

Diabetes, which afflicts about 10% of patients, their frequency increases with increasing age of patients, and the average age of the diagnosis of diabetes associated with cystic fibrosis is about 20 years.

Author

Sue P. Simon