Laron's syndrome is a pathological condition in which the body is not able to perceive and use growth hormone. The most common sign of this disorder is dwarfism. Other symptoms include muscle weakness and decreased stamina, childhood hypoglycemia, delayed sexual development, shortened limbs, and obesity. Most often, pathology is caused by changes (mutations) in the gene responsible for growth. It is inherited by an autosomal recessive trait.
Symptoms
Laron's syndrome is a fairly rare disorder. With this diagnosis, newborn children, as a rule, have average statistical indicators of growth and weight, however, in the future their physical development slows down sharply. If untreated, adult men reach a maximum height of 130 cm. The height of women does not exceed 120 cm.
In addition to low growth, the following symptoms indicate the presence of pathology:
- muscle weakness, lack of endurance;
- hypoglycemia in childhood;
- delayed puberty;
- disproportionately small genitals;
- thin, weak hair;
- violations of the structure of teeth;
- shortened limbs;
- obesity;
- distinctive features (protruding forehead, sunken nose, blue sclera syndrome).
Causes
Laron’s syndrome causes mutations in a gene that contains a growth hormone receptor — a protein located on the outer shells of cells throughout the body. The growth hormone receptor is designed to recognize and activate somatotropin, thereby initiating cell growth and division. Mutations in the gene interfere with the normal functioning of this biological mechanism and lead to impaired cell development. Many symptoms of pathology are caused by the inability to produce a secondary hormone - an insulin-like growth factor.
Heredity
In most cases, Laron’s syndrome in children is inherited in an autosomal recessive manner. This means that the violation is caused by mutations in both copies of the affected gene in each cell. Parents of a patient with a pathology usually carry one mutated copy of the gene and rarely suffer from typical manifestations of the disorder. When a child is born in two carriers of an autosomal recessive disease, the risk of inheriting a pathology is 25%; the probability of becoming a passive carrier, like each of the parents, is 50%; the chance to inherit neither pathology nor the mutated gene is 25%.
According to some reports, there are families in which Laron’s syndrome is inherited in an autosomal dominant manner. In such cases, a mutation in one copy of the affected gene in each cell is sufficient to transmit the disease. Sometimes, on this basis, the child adopts the pathology from the sick parent. There are also known cases of new, non-hereditary genetic mutations, when the disorder is diagnosed in children whose families have not had a single case of the disease. A person with a confirmed pathology passes the mutated gene to his children in 50% of cases.
Diagnostics
After an initial assessment of the obvious signs and symptoms, a specialist can diagnose Laron’s syndrome (see the article for photos of people with pathology). To confirm this diagnosis and effective differentiation, additional examinations are carried out, including a blood test for specific hormones. Most often, in people with this disorder, an increase in the level of growth hormone is observed simultaneously with a decrease in the insulin-like growth factor. In some cases, doctors prescribe genetic studies to confirm the fact of a gene mutation. The results of diagnostic measures can accurately determine Laron's syndrome.
Treatment
Modern medicine is not yet able to completely cure this pathological condition. Innovative therapy is primarily focused on the acceleration of growth, which is provided by the method of subcutaneous injection of the missing insulin-like hormone. The substance stimulates linear growth (in height), accelerates the development of the brain and prevents the occurrence of metabolic disorders caused by a protracted deficiency of essential proteins. In addition, such injections raise blood sugar, prevent the accumulation of cholesterol and significantly tone up muscle tissue. Treatment with an insulin-like growth factor should be carried out under the vigilant supervision of specialists, since exceeding the required dosage can lead to serious health problems.
Forecast
The long-term outlook is most often quite optimistic. Laron's syndrome in no way affects life expectancy. Moreover, carriers of this hereditary pathology are much less at risk for cancer and non-insulin-dependent diabetes mellitus. Extensive research is currently underway to identify the links between Laron syndrome, genetic mutations, growth hormone, and the development of malignant tumors. It is possible that it is in such gene changes that the key to victory over cancer lies.