Mucoviscidosis (cystic fibrosis): symptoms and therapy

Mucoviscidosis (cystic fibrosis): symptoms and therapy

Cystic fibrosis is a hereditary disease in which the glands in the body produce viscous mucus. As the disease progresses, this can lead to various symptoms and permanently damage organs such as the lungs, pancreas, liver or small intestine. Although the disease, also known as cystic fibrosis, cannot be cured, early and consistent therapy increases life expectancy. Here, you can learn more about the metabolic disease, its causes and treatment, and newborn screening to test for cystic fibrosis.

What is cystic fibrosis?

Mucoviscidosis (also cystic or cystic fibrosis, in short, CF) is one of the most common congenital metabolic diseases in light-skinned people. Due to a gene mutation, the disease causes viscous mucus to form in the body’s glands, which is difficult to drain. This causes symptoms such as chronic bronchitis, indigestion and a malfunctioning pancreas. Even if the lungs are typically affected, cystic fibrosis is not just a lung disease but a multi-organ disease.

Overall, the disease is not very common:  around 200 to 300 children are born with this disease in Germany every year, and there are currently around 8,000 patients in Germany. Girls and boys are affected equally often.

 

Causes of Cystic Fibrosis

Cystic fibrosis is not contagious but is a hereditary disease. The cause is an inherited change in a gene on chromosome 7. This gene is also the CFTR (cystic fibrosis transmembrane conductance regulator). Different types of CFTR mutations can occur.

As a result of the mutation of this gene, there is a disturbed development of specific channels in the cells of the body’s glands. These channels are generally responsible for transporting specific salt components (chloride ions) out of the cell, resulting in the outflow of water from the cells. This liquefies the mucus produced by the epithelial cell. However, due to the altered production of these ion channels, chloride and water are not released into the glandular secretion or filtered out.

The result is a changed composition of the secretions: the sweat glands produce highly salty sweat, while the mucus in the lungs and intestines and the digestive juices of the pancreas are very viscous. This viscous mucus is difficult to remove, especially from the bronchial cells, and causes a build-up of secretion, impairs breathing and results in recurring infections.

Cystic fibrosis: heredity

Cystic fibrosis is inherited in what is known as an autosomal recessive mode of inheritance. This means a person only becomes ill if they inherit chromosome 7 with a defective gene from their father and mother. The disease does not break out in people with one affected and one healthy chromosome. However, they can pass the defective gene on to their children and are, therefore, referred to as healthy disease carriers.

 

What are the symptoms of cystic fibrosis?

Cystic fibrosis manifests through various symptoms, which can vary in severity depending on the exact expression of the gene mutation. Usually, the first symptoms appear as a child; only rarely is the diagnosis made when those affected are already adults.

Possible signs of the disease are:

Cystic fibrosis often leads to other diseases. These include, for example, frequent infections of the respiratory tract ( pneumoniabronchitissinusitis ), diabetes, gallstones, inflammation of the pancreas or liver, and osteoporosis. Salt loss syndrome can also occur: increased salt loss through sweating can cause muscle pain, headaches, dizziness, or muscle cramps, mainly due to fever and physical activity.

Below, we explain what causes these symptoms.

Airways particularly affected

The respiratory tract and lungs are usually particularly severely affected: Normally, foreign bodies and other disturbing substances are carried out by coughing with the help of the so-called cilia. However, the mucus produced by the bronchial glands in people with cystic fibrosis is so viscous that the ciliated bronchial tubes cannot transport it away. Despite chronic coughing, he is not coughed up.

This creates a secretion blockage, which forms an ideal breeding ground for fungi and bacteria. As a result, recurring infections such as pneumonia and chronic bronchitis occur. In addition, inflammation of the paranasal sinuses often occurs with cystic fibrosis since mucus drainage from the paranasal sinuses is also more difficult.

Due to the frequent inflammation, lung tissue is damaged and scarred. As a result, the lung function gradually decreases. In the advanced stage, patients often suffer from lung weakness and a lack of oxygen supply. The chronic lack of oxygen can cause so-called watch glass nails and drumstick fingers.

Malnutrition due to indigestion

The digestive system is also usually affected in cystic fibrosis. The secretion produced by the pancreas is also viscous and blocks the so-called excretory ducts of the gland.

On the one hand, this means that the digestive enzymes contained in the secretion are not released into the small intestine, and the food cannot be adequately utilized. People with cystic fibrosis, therefore, often have vitamin deficiencies and growth disorders; children, in particular, are usually underweight and too small for their age. Diarrhea, constipation or fatty stools can also occur.

On the other hand, gland cells are damaged by the accumulation of secretions in the pancreas and replaced by connective tissue (fibrosis). In the long term, this leads to a loss of function of the pancreas, which can manifest itself in a chronic lack of digestive enzymes and diabetes mellitus.

Due to the viscous bile, gallstones and bile congestion can also occur. Possible consequences of this can be liver inflammation and, in the further course, cirrhosis of the liver, which may manifest as jaundice (icterus).

 

Infertility in cystic fibrosis

In addition to the respiratory and digestive systems, the sexual organs can also be affected, which is why many adults with cystic fibrosis have impaired fertility. In 98 per cent of the affected men, the vas deferens are either stuck together or entirely missing from birth. Both of these lead to the affected patients being unable to father children. Although sperm are produced in the testicles, they cannot be ejected during ejaculation.

Affected women usually have reduced fertility because the mucus in the cervix is ​​more challenging than in healthy women, making it difficult for the male semen to penetrate. Nevertheless, patients with cystic fibrosis may be able to conceive children naturally. However, artificial insemination can be an option for both sexes.

Intestinal obstruction in babies is the first sign.

In about 10 to 15 per cent of all children suffering from cystic fibrosis, an intestinal blockage (meconium ileus) immediately before or after birth is the first sign of the disease. Undigested amniotic fluid components in connection with tough intestinal mucus lead to the intestines sticking together. The babies show this vomit and do not pass the first bowel movement (meconium, child speech). In addition, the abdomen is often bloated.

To remove the blockage of the intestine, an enema with a contrast medium is usually performed under X-ray fluoroscopy. An operation is usually necessary if the intestinal obstruction persists or complications arise.

Diagnosis: Test for cystic fibrosis

Screening for cystic fibrosis in newborns has been standard in Germany since 2016. This newborn screening is a voluntary preventive service, the costs of which are borne by the statutory health insurance companies.

First, the level of a digestive enzyme in the pancreas – the so-called immunoreactive trypsin – in the blood is determined. If this test is positive, the laboratory conducts further tests (PAP and genetic tests for the most common CFTR mutations).

If the suspicion of cystic fibrosis persists, a sweat test  (pilocarpine iontophoresis test) is conducted to confirm the diagnosis. The salt content in the sweat is measured. If this is significantly increased, this confirms the diagnosis of cystic fibrosis.

However, if the test results are unclear and need to be clarified, a so-called potential difference measurement can also be carried out. For this purpose, a tissue sample is taken from the nasal mucosa or the rectum, and its electrical properties are determined. If the disease is cystic fibrosis, the electrical potential on the mucous membrane is changed due to the cells’ disturbed water and salt balance.

 

Other tests for cystic fibrosis

In addition to these tests, which can be performed on children and adults, a genetic blood test can detect the CFTR mutation in the genome. The type of mutation is also determined, which can provide more precise information about the severity and severity of the disease.

A prenatal diagnosis of cystic fibrosis only makes sense if there is already a sick child in the family, a parent is sick themselves, or if relatives have the disease and the parents are healthy carriers. Genetic testing of the amniotic fluid (amniocentesis) or a sample of the child’s part of the placenta (chorionic villus biopsy) can identify the genetic defect in the child’s genome.

Once the condition has been diagnosed, measuring the oxygen level in the blood and checking lung function can help determine the extent of lung impairment.

Cystic fibrosis must be differentiated from other diseases that can initially cause similar symptoms (differential diagnosis). These include, for example, lung diseases such as asthma, bronchitis, but also celiac disease.

Therapy for cystic fibrosis

There is no cure for cystic fibrosis, but nowadays, there are numerous therapeutic options to treat the symptoms of the respective organ systems:

  • For the airways, mucus-loosening procedures are in the foreground: Physiotherapeutic treatments such as tapping massages and learning self-cleaning techniques such as autogenous drainage facilitate mucus transport from the lungs. In addition, regular inhalations with expectorant, antibacterial and bronchodilator drugs are helpful.
  • Breathing training and special exercises can improve the function of the lungs. If the lung function is severely restricted, supportive oxygen therapy may be necessary. In some cases, however, the lungs are so severely damaged in the advanced stage of the disease that a lung transplant must be considered.
  • To treat and prevent infections, consistent therapy with antibiotics is usually necessary.
  • Pancreatic enzymes can be taken in pill form to help digest food. High-calorie food, vitamin preparations and other food supplements can also counteract malnutrition.
  • In the case of liver inflammation or impairment of the bile ducts, medication containing the active ingredient ursodeoxycholic acid can be taken to prevent liver cirrhosis.
  • People with cystic fibrosis are entitled to nutritional therapy at the expense of statutory health insurance companies. You should also ensure that you drink enough fluids to liquefy the mucus. In addition, electrolytes can be taken if, for example, there is increased salt loss through sweating on hot days.

In addition to a lung transplant, a transplant of other organs, such as the liver, may also be necessary. Treatment often occurs in special outpatient clinics or centres for cystic fibrosis. In such centres, affected families also receive tips on living with cystic fibrosis.

Generally, the earlier the treatment starts and the more consistently it is carried out, the better the prognosis.

Drugs for cystic fibrosis

Even if the genetic defect cannot be remedied with medication, there are various medications for treating cystic fibrosis, so-called CFTR modulators. These can support symptomatic treatment.

The active substance ivacaftor can help to improve the function of the faulty ion channels and thus normalize the salt and water balance. Ivacaftor (trade name Kalydeco®) is approved from four months of age. However, the agent is only effective on specific CFTR mutations.

In addition, the active ingredients ivacaftor and lumacaftor can be used in patients with specific CFTR mutations to support the effect of ivacaftor. As so-called correctors, they can reduce the construction of faulty ion channels.

Other treatment approaches, such as gene therapy, are currently the subject of research.

 

Improve performance through sport.

Sport is not forbidden with cystic fibrosis; on the contrary, physical activity can positively affect the course of the disease. Exercise can improve the body’s resilience and strengthen heart and lung function. Gentle endurance sports such as cycling or walking are usually suitable. Before starting the training, however, those affected should seek medical advice.

The ability to perform in the case of cystic fibrosis varies significantly from person to person. For example, there are repeated reports of those affected who run a marathon thanks to consistent therapy and intensive training.

Prognosis: Life expectancy has increased significantly

After cystic fibrosis was long considered a childhood disease, the life expectancy of those affected has increased significantly in recent decades. With early diagnosis and careful treatment, severe infections and consequential damage to the organs can often be prevented today. While just a few decades ago, most sick children died before the age of ten, people with cystic fibrosis who are born today have a good chance of living to over 40 years of age.

How do you die from cystic fibrosis?

Cystic fibrosis is a progressive disease that leads to irreversible damage to organs over time, for example, through scarring of the lung tissue. In the final stages of the disease, the lungs (or other organs) can no longer do their job. Failure to replace it with a lung transplant in time will result in lung failure. Therefore, cystic fibrosis is always fatal.

A variety of complications can also occur, such as pneumothorax, which causes the lungs to collapse, or heart failure. Due to the accumulation of secretions in the organs, especially the lungs, pathogens cannot be transported away, often leading to pneumonia and other life-threatening infections.

 

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