Deficiency of hemoglobin
Normally hemoglobin consists of four protein chains (globins), each of which is associated with an oxygen-transporting molecule - heme. There are two types of globins - alpha and beta globins. Uniting in pairs, they form a molecule of hemoglobin. The production of different types of globins is balanced, so they are present in approximately equal amounts in the blood. With thalassemia, the synthesis of alpha- or betaglobins is disrupted, which leads to a disruption in the construction of the hemoglobin molecule. It is the lack of normal hemoglobin in the blood that leads to the development of anemia and other symptoms of thalassemia.
There are two main types of thalassemia:
- beta-thalassemia - is associated with a violation of beta-chain production globin;
- alpha-thalassemia - is characterized by a violation of the synthesis of alpha chains of globin. Both diseases have a number of subtypes, differing in severity. Alfa-thalassemia in all its forms has a much lighter course.
There are three forms of beta-thalassemia: small thalassemia, intermediate thalassemia and large thalassemia. Symptoms of small thalassemia are minimal, but carriers of defective genes risk transferring it to their children in a more severe form. The cases of beta-thalassemia are registered all over the world, but it is more common in the Mediterranean and the countries of the Middle East. Almost 20% of the population of these regions (more than 100 million people) have thalassemia gene. It is the prevalence of this disease in the Mediterranean countries that explains its name ("thalassemia" translates as "Mediterranean anemia").
Blood tests
Patients with small beta-thalassemia usually feel normal and do not look sick. Most often, it is detected by accident in a general blood test. Moderate anemia is observed in patients. The microscopic picture of blood is very similar to the widespread iron deficiency anemia. However, additional research makes it possible to exclude the presence of a deficiency of this trace element. At the expanded analysis the abnormal quantitative parity of components of a blood is revealed.
Forecast
A child who has a small beta-thalassemia develops normally and does not need treatment, but he may be predisposed to anemia in the distant future, for example, during pregnancy or during infectious diseases. Small beta-thalassemia plays a role as a protective factor against malaria. This may explain the high prevalence of thalassemia in the countries of the Middle East. Large beta-thalassemia occurs when the child has inherited the defective genes responsible for the synthesis of beta-globin from both parents, and his body does not produce beta-globin in a normal amount. At the same time synthesis of alpha chains is not broken; they form insoluble inclusions in erythrocytes, as a result of which these blood cells decrease in size and become pale in color. The lifetime of such erythrocytes is less than usual, and the development of new ones is significantly reduced. All this leads to severe anemia. Nevertheless, this type of anemia, as a rule, is not manifested until the age of six months, since during the first months of life the so-called fetal hemoglobin predominates in the blood, which is subsequently replaced by ordinary hemoglobin.
Symptoms
A child with a large thalassemia looks unhealthy, he is apathetic and pale, may lag behind in development. Such children may have decreased appetite, they are not gaining weight, they start to walk late. A sick child develops severe anemia accompanied by characteristic disorders:
- a typical facial structure (the so-called Mongoloid face);
- characteristic changes in bones - the so-called "hairy skull" symptom (needle-shaped periostosis) associated with bone marrow hyperplasia is radiological;
- thinning and fractures of bones.
Thalassemia is an incurable disease. Patients suffer from associated disorders throughout life. Modern methods of treatment can prolong the patient's life. The basis for the treatment of large beta-thalassemia are regular blood transfusions. After the diagnosis, the patient is given blood transfusions, usually a groove in 4-6 weeks. The purpose of such treatment is to increase the amounts; blood cells (normalization of the blood formula). With the help of blood transfusions, control over anemia is provided, which allows the child to develop normally and prevents characteristic deformations of the bones. The main problem associated with multiple blood transfusions is excessive iron intake, which has a toxic effect on the body. Excess iron can damage the liver, heart and other organs.
Treatment of intoxication
To eliminate intoxication, intravenously injected drug deferoxamine. Usually prescribe eight-hour infusions deferoxamine 5-6 times a week. To speed up the removal of excess iron, oral intake of vitamin C is also recommended. This mode is extremely burdensome for the patient and his loved ones, so it is not surprising that patients often do not adhere to standard treatment regimens. Such therapy significantly increases the life expectancy of patients with large beta-thalassemia, but does not cure it. Only a small proportion of patients survive to 20 years of age, the prognosis for them is unfavorable. Despite ongoing treatment, children with this type of thalassemia rarely reach puberty. A frequent manifestation of thalassemia is the enlargement of the spleen, accompanied by the accumulation of red blood cells in it, leaving the bloodstream, which aggravates anemia. To treat patients with thalassemia, they sometimes resort to surgical removal of the spleen (splenectomy). However, in patients who have undergone splenectomy, there is an increased susceptibility to pneumococcal infection. In such cases, vaccination or lifelong prophylactic antibiotics is recommended. In addition to small and large beta-thalassemia, there are also intermediate beta-thalassemia and alpha-thalassemia. Examination of pregnant women with signs of small thalassemia reveals the presence of severe forms of the disease in the fetus. There is a third type of beta-thalassemia, known as intermediate beta-thalassemia. This disease in severity is between small and large forms. In patients with intermediate thalassemia, the hemoglobin level in the blood is somewhat reduced, but sufficient to allow the patient to lead a relatively normal life. Such patients do not require blood transfusions, so they are at a much lower risk of complications associated with excess iron in the body
Forecast
There are several types of alpha-thalassemia. At the same time, there is no clear division into large and small forms. This is due to the presence of four different genes responsible for the synthesis of alpha globin chains that make up hemoglobin.
Disease severity
The severity of the disease depends on how many of the four possible genes are defective. If only one gene is affected, and the other three are normal, the patient usually does not show significant abnormalities in the blood. However, with the defeat of two or three genes progressively worsens. Like beta-thalassemia, alpha thalassemia is prevalent in areas that are endemic for malaria. This disease is typical of Southeast Asia, but is rare in the Middle East and the Mediterranean.
Diagnostics
The diagnosis of alpha-thalassemia is based on the results of a blood test. The disease is accompanied by severe anemia. In contrast to beta-thalassemia, with alpha-thalassemia there is no increase in hemoglobin HA2. Large beta-thalassemia can be detected before birth. If, on the basis of the history or results of the planned examination, the woman is the carrier of the gene for small thalassemia, the future father is also examined for thalassemia. When a gene for small thalassemia is detected in both parents, an accurate diagnosis can be made in the first trimester of pregnancy on the basis of fetal blood. When a fetus is diagnosed with signs of large beta-thalassemia, abortion is indicated.