Diagnosis of cystic fibrosis
Symptoms and signs of the disease are very specific, but may vary depending on the severity of the course.
These include:
■ Insufficiency of pancreatic function (observed in 85% of patients);
■ pulmonary insufficiency and bronchiectasis (abnormal bronchial dilatation), which develop as a result of the accumulation of adhesive mucus in the respiratory tract;
■ Digestive dysfunction associated with ineffective organ function leading to weight loss and weight loss.
Within the same family, the severity of lung damage in children may vary, but pancreatic dysfunction in most cases has the same severity. Lung infection is one of the main causes of death of patients suffering from cystic fibrosis. Most often this is due to a bacterial infection that is not amenable to treatment. The accumulation of viscous mucus in the airways creates ideal conditions for the development of microorganisms. People suffering from cystic fibrosis are particularly prone to infection with the bacterium Pseudomonas aeruginosa. Healthy lung cells are able to withstand invading microorganisms. In patients with cystic fibrosis, this function is impaired, resulting in a predisposition to the development of chronic pulmonary infections.
Treatment of cystic fibrosis
Improving the methods of treatment of cystic fibrosis, including antibiotic and physiotherapy, aimed at clearing the lungs of mucus, has increased the average life expectancy of patients up to 30 years. Most patients with cystic fibrosis are infertile. The cause of male infertility is the congenital absence of the vas deferens, the ducts through which the sperm comes from the testicles into the urethra. In women, infertility is associated with the presence of abnormal mucus in the cervix. However, at present such patients can have children with the help of artificial insemination. Among representatives of the white European race, one out of 25 people is a carrier of the cystic fibrosis gene. Since this gene is recessive, it must be inherited from both parents for the manifestation of disease symptoms. Among representatives of the white European race, the carrier of the defective gene of cystic fibrosis is approximately 1 person out of 25. Such people are called heterozygous. They have no clinical signs of the disease and the risk of developing cystic fibrosis. In such a population, the chances that both partners in the pair will be carriers of the defective gene are 1: 400 (that is, 1 pair out of 400). Each carrier has a 50% risk of transmitting the mutated gene to each child. When both partners in a pair are carriers, each child has a clear picture of the risk of inheriting a defective gene.
■ The risk of cystic fibrosis due to the inheritance of two defective genes is 1: 4.
■ The risk of becoming a carrier of a defective gene when inheriting one defective and one normal gene is -1: 2.
■ The chance to inherit two normal genes and remain unaffected by a defective gene-1: 4.
Individuals who inherited two defective genes are called homozygous, and those that inherited one gene are heterozygous, or carriers. Carriers have the risk of having a sick child if their partner also carries a defective gene. Individuals who are not carriers of the gene are not at risk of developing the disease in their future children. Couples, in which each is a carrier, have a probability of 1: 4 that they have a sick child. The severity of the disease can vary over a wide range. Most patients are diagnosed before the age of one year, but a mild form of the disease can be diagnosed in middle age, sometimes accidentally, when examined for infertility. The increased salt content on the skin surface can serve as a diagnostic indicator of cystic fibrosis. The modern "lot test" is a more complex analogue of the method previously used by midwives who licked the forehead of a newborn to detect an abnormally high level of salt in the sweat. Even then it was known that a high level of salt is an indicator of pulmonary insufficiency. Cystic fibrosis is one of the most common autosomal recessive hereditary diseases among representatives of the white European race and occurs on average in 1 out of 400 children born. Not all ethnic groups have such a high incidence rate. For example, in representatives of Hispanic or Latino origin, the incidence is 1 case for 9,500 newborns, and for Africans and Asians, less than 1 case per 50,000 children born. Most of the ethnic groups studied have lower incidence rates than representatives of the white European race. However, it is difficult to predict the level of morbidity in a mixed population. About 25% of the inhabitants of Northern Europe are carriers of the defective gene of cystic fibrosis. For example, in the UK, the disease occurs in 1 child from 4,000 births (including children of other races, except white).