Definition of thalassemia
Thalassemia is a genetically transmitted blood disease, in which the body synthesizes an abnormal form of hemoglobin.
As is known to most, hemoglobin is a protein contained in red blood cells, essential for the transport of oxygen in the blood. In subjects suffering from thalassemia, the mutated form of hemoglobin causes the gradual but inexorable destruction of red blood cells, up to anemia.
From medical statistics it can be seen that thalassemia affects mainly the inhabitants of Middle Eastern countries, African countries and all those who inhabit swampy places (not by chance, thalassemia is also called Mediterranean anemia ).
Classification and causes
Depending on the defective protein sub-unit (which makes up hemoglobin), two forms of thalassemia can be distinguished; before proceeding with the analysis, let's take a step back to clarify some very important concepts.
Hemoglobin is the carrier par excellence, used to transport oxygen in the blood; it consists of two proteins, known as alpha-globulin and beta-globulin.
Thalassemia occurs when one or more genes that control the production of one or both of these proteins are defective (mutated).
Thalassemia is caused by a DNA mutation of the proteins that make up hemoglobin: these alterations heavily affect the physiological hemoglobin synthesis and, destroying erythrocytes, result in anemia.
The classification of thalassemia must be made on the basis of two important factors:
- Number of mutated genes inherited from parents
- Type of protein involved (alpha or beta hemoglobin)
Alpha Thalassemia
In the "alpha" form of thalassemia - in which the 4 "alpha" globular subunits of hemoglobin can be mutated (at the level of chromosome 16) - one or more defective genes are involved; every globular sub-unit is clearly encoded by a gene, so there are 4 genes that can be involved.
The general symptom picture becomes more serious when three or four genes are involved: in the first case, we speak of " hemoglobin H disease " (with moderate or severe symptoms). When all four genes are involved, the disease is called alpha-thalassemia major : in similar situations, the newborn dies shortly before birth or immediately afterwards.
Beta Thalassemia
The beta form of thalassemia, as can be guessed, occurs when the genes involved in the composition of beta chains (at the level of chromosome 11) are changed: in this case, only two genes can be affected. If only one gene is changed, it is called beta-thalassemia minor, in which the patient does not complain of relevant symptoms. Similar to the alpha variant, the involvement of both genes constituting the beta chains of hemoglobin causes a beta-thalassemia major (or Cooley anemia ), which reflects severe and severe symptoms; in this case, however, the symptoms generally begin a couple of years after birth.
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To learn more: Symptoms Thalassemia
Thalassemia is a very serious hereditary disease, so that some of its variants, such as alpha-thalassemia major, can cause the death of the child during childbirth or immediately after birth. However, newborns with beta-thalassemia major can survive and develop the first symptoms within a couple of years of birth (severe anemia).
If only one gene is altered, both in the alpha form and in the beta form of thalassemia, patients do not complain of any appreciable symptoms; only by microscopic analysis of a blood sample taken from the patient can an anomaly be observed in the shape and structure of the erythrocytes, which are much smaller than normal.
In addition to anemia, patients with thalassemia may experience one or more of the following symptoms: fatigue, mood alteration (irritability), growth deficit, deformity of facial bones, jaundice, shortness of breath and dark urine.
In cases of severity, the symptomatic picture of a patient suffering from thalassemia can degenerate, creating real bone deformities, especially on the face and skull; thalassemia can favor an abnormal expansion of the bone marrow, both by weakening the bone mass and by enormously increasing the risk of bone fractures.
One of the complications of thalassemia is the possible accumulation of iron (hemochromatosis), an expression of both the disease itself and the recurrent blood transfusions that the patient needs.
Thalassemia is often the cause of splenomegaly, that is to say an exaggerated volumetric increase in the spleen: often, this pathological clinical condition requires splenectomy, the surgical removal of the organ. As we know, the spleen is an important organ used for the synthesis of white blood cells and antibodies, in addition to infection control: its removal clearly favors a reduction in the defense function against bacterial and viral insults, making the subject more sensitive to infections . However, it should be pointed out that thalassemia itself also increases the risk of contracting infections: in the case of excision of the spleen in the context of thalassemia, the chances of infection increase excessively.
Diagnosis
If the father and / or mother are affected by thalassemia, the probability of transmitting the disease to the offspring is very high. We have analyzed that not all forms of thalassemia begin with a precise symptomatology at birth: in similar situations, in case of suspected thalassemia, it is possible to subject the patient to a series of specific tests and examinations, aimed at diagnostic assessment (such as the determination of hemoglobin A2, which is high in healthy subjects carrying Beta-thalassemia genes).
Among the physical examinations, the medical palpation of the spleen can ascertain, at times, a thalassemia: splenomegaly, as previously mentioned, constitutes a first warning signal for Mediterranean anemia. Blood tests are more specific and precise: in a blood sample of a thalassemia, red blood cells, when viewed under a microscope, appear small and have an abnormal shape. Again, a careful blood count of a patient suffering from thalassemia reveals severe anemia: this test is useful for blood iron counts, to perform DNA analysis for the diagnostic assessment of the disease and to evaluate the possible mutation of the 'hemoglobin.
Instead, hemoglobin electrophoresis reveals the abnormal form of oxygen transport proteins.
Some variants of thalassemia cannot be diagnosed with electrophoresis: in this case, the patient will be subjected to the "mutational analysis" test, useful for detecting and ascertaining thalassemia.
Medications and treatments
See also: Medicines for the treatment of thalassemia
Being a genetically transmitted disease, it is understandable that - for the moment - there is no drug capable of reversing the disease; however, symptoms can be controlled, improving the patient's quality of life. The choice of a cure rather than another depends on the type of thalassemia and the severity of the symptoms.
In the mild variant of thalassemia (in which, for example, only one gene is changed), no drugs are needed, since the patient does not complain of symptoms. In such circumstances, it is advisable to carry out the necessary checks regularly; occasionally, occasional blood transfusions are useful (especially in the case of surgery and childbirth).
For the symptomatic forms, of moderate or serious entity, the therapeutic approach is different, and may require frequent blood transfusions or, in the most serious cases, stem cell transplantation.
- Blood transfusions: even this therapeutic approach can create serious complications, since frequent transfusions can favor a pathological accumulation of iron in the blood (hemochromatosis), which requires specific treatment aimed at eliminating iron storage, known as therapy chelator (with drugs like Deferasirox and Deferiprone). For further information: read the article on drugs for the treatment of hemochromatosis.
- Bone marrow transplant: reserved for the most serious cases, in which thalassemia creates heavy dysfunctions in the body.
