Thalassemia
What are thalassemias ?
Thalassemias are a heterogeneous group of hereditary blood disorders (transmitted from parents to children), whose common characteristic is a defect in the synthesis of one or more of the globin chains (which are the chains that form hemoglobin, the protein that carries oxygen, inside red blood cells). In adults, this protein is composed of four chains ( 2 α and 2 β and, very rarely, 2 α and 2 δ ).
In thalassemia, there is a genetic disorder that prevents the alpha or beta chains from forming properly and to varying degrees of severity. As a result, and depending on the type of thalassemia, the red blood cells containing this altered hemoglobin are smaller in size (microcytosis) and may have a greater tendency to rupture (hemolysis). This, in severe cases, produces anemia (hemolytic and microcytic anemia) that prevents the necessary oxygen from being transported to all the cells of the body, in addition to other alterations in different organs.
Thalassemia is the most common genetic disease in the world (although many people are carriers and do not have symptoms).
It is important to diagnose thalassemias (even the asymptomatic forms or those with very little clinical expressiveness), to make adequate genetic counseling, and prevent the appearance of severe cases of thalassemia.
The severity of symptoms varies depending on the type of thalassemia:
· If it is mild, it may be asymptomatic.
· If it is moderate or severe, it can manifest with jaundice, a feeling of satiety or abdominal discomfort, and, since there are not enough red blood cells and not enough oxygen reaches the body, tiredness, weakness, and difficulty breathing - anemia -.
· In the major forms of thalassemia, there may be enlargement or weakening of some bones, an enlarged spleen, and heart problems, which can lead to death.
Asymptomatic thalassemias do not require treatment, but moderate or severe thalassemias may require regular blood transfusions or even a bone marrow transplant.
What types of thalassemias are there?
Hemoglobin, which carries oxygen to all cells in the body, is made up of two different main parts or chains called alpha and beta globins. (There is also the delta, although less frequent). If the body does not produce either of these two proteins or does so in an inadequate amount, the hemoglobin that is formed does so in an unbalanced way, lacking the altered globin and generating an excess of what is normally produced. These precipitates are formed inside the cells (red blood cells or erythrocytes) and are responsible for their early destruction, both in the bone marrow itself (ineffective erythropoiesis) and in the peripheral blood (hemolysis). In addition, these red blood cells (RBCs) have a decreased volume, size, and amount of normal hemoglobin.
Each thalassemia is named after the chain that is no longer synthesized:
· Alpha-thalassemia. As its name suggests, genetic defects affect the production of the alpha globin chain.
· Beta-thalassemia . Genetic defects affect the production of the beta-globin chain.
Hundreds of mutations have been described that can give rise to different forms of thalassemias.
Human beings (like many other living beings) store genetic information in pairs (we have 23 pairs of chromosomes, half from the mother and half from the father). If the inheritance is heterozygous, only one of the chromosomes carries altered genes, this generally leads to a lower expression of the disease. If the alteration affects both chromosomes (homozygous) then the severity is greater. Thus, according to its severity, thalassemias can be classified as:
· minor. It does not cause symptoms.
· intermediate. Symptoms range from mild to severe.
· Elderly. The disorder is inherited from both parents (homozygous) and is a more severe form that requires treatment, sometimes periodic blood transfusions.
In summary, we can find:
Beta thalassemias:
· Beta thalassemia minor (or thalassemia trait): this is the most common form of β-thalassemia in the World, as well as in the countries on the Mediterranean coast. People who are carriers of the thalassemic trait generally do not present clinical manifestations, and their finding is usually incidental on the occasion of a routine hematological examination. There may be no anemia or very slight anemia (Hb 10-12 g/dl). Genetic analysis confirms the disease
· Intermediate beta-thalassemia: corresponds to forms in which there may be some signs and symptoms of different intensity, although they always present anemia (Hb between 8-10 g/l) with the hemolytic syndrome (red blood cell rupture) and splenomegaly (increase in the size of the spleen). These patients do not usually depend on transfusions and also, like all thalassemias, it can be confirmed by the genetic study.
· Beta thalassemia major: Transmission comes from both parents passing on the β chain alteration. The most severe form is Cooley's anemia., a very severe congenital hemolytic anemia (a consequence of premature destruction of red blood cells). The disease begins to manifest itself from the fifth-sixth month of life. During the first 2 years of life, these patients present pallor, irritability, sleep disturbances, food refusal, and recurrent infections. The anemia is very intense and complications progressively appear such as the enlargement of the spleen (splenomegaly) and enlargement of the liver (hepatomegaly). They also present bone alterations with deformities (long, thin bones) and spontaneous fractures. They usually require constant transfusions and their complications are the cause of death in these patients, generally before the age of 25.
Alpha thalassemias:
· Alpha+ thalassemia (silent carrier): appears when the mutation occurs in a single gene. They are healthy people, without clinical manifestations. It can only be detected by DNA study. It does not require treatment.
· Thalassemia alpha0 or thalassemia minor alpha (thalassemia trait): appears if the mutation is in two genes. It generally does not present clinical manifestations. It does not require treatment.
· Intermediate grade alpha thalassemia (or hemoglobinopathy H): This appears if the mutation is of three genes. Symptoms and signs are similar to those of beta thalassemia intermedia. It is common that if these patients suffer from infections (such as flu, urinary tract infections, or angina) hemolytic anemia increases. Anemia can also increase if certain drugs are taken that are contraindicated (antimalarial drugs, some vitamins such as K, and some antibiotics). Due to this, they are patients who require periodic control by the doctor. Sometimes they require transfusions.
· Alpha thalassemia major (Bart's hemoglobinopathy): it appears if the mutation of the four genes occurs. It is almost exclusive to Southeast Asian countries (China, Philippines, Thailand). It is a very serious form, incompatible with life. Death occurs before or immediately after birth.
What symptoms does thalassemia produce?
As has been mentioned, the symptoms of thalassemias can vary from being an asymptomatic carrier, suffering from it without symptoms and only changes in blood tests, or suffering from mild symptoms and signs or even certain types with life threats. Each type of thalassemia presents different signs and symptoms since thalassemia is not a single disease as such but a group of diseases, thalassemia.
However, the signs and symptoms of thalassemias may include:
· Alterations in blood analysis: they can range from the occasional finding, without clinical repercussions, to microcytic and hemolytic anemia. Depending on its severity, it can cause weakness and a sensation of suffocation.
· Difficulty concentrating.
· Paleness or jaundice -yellowing of the whites of the eyes and skin.
· Enlargement of the spleen, which can lead to a feeling of fullness and abdominal discomfort.
· Ulcers on the skin.
· Darkening of the urine.
· Gallstones.
· Widening and enlargement of some bones, especially those of the head and face, which can lead to facial deformities.
· Weakening of the long bones of the arms and legs, which are easily fractured.
· Slower growth in children with beta-thalassemia major and delayed puberty.
· Accelerated heart rate.
What complications can they have?
People with thalassemia may accumulate too much iron due to increased absorption and frequent blood transfusions. The excess minerals can deposit in the heart and lead to iron overload disease, heart failure, or premature death.
Thalassemia can also damage the liver and the endocrine system and, therefore, the glands that regulate body processes, such as the thyroid and adrenal glands, through the production of hormones.
Also, thalassemias can increase the risk of infections or be aggravated as a result of them.
How is thalassemia treated?
If the person with thalassemia has no or mild symptoms, treatment is usually not necessary. In case they are moderate or severe, the following therapeutic measures can be used:
· Blood transfusions, accompanied by medication that prevents iron overload.
· Folic acid supplements.
· Bone marrow transplant, also called a stem cell. According to SEMERGEN, it is the only treatment that currently cures the disease and its average survival rate of more than 5 years is 75-90%.
· Finally, in the case of an enlarged spleen, it may be necessary to remove this organ (splenectomy).
Who does thalassemia affect?
The most frequent form in World is β-thalassemia minor, although its distribution is very irregular.
According to data published by the World Society of Primary Care Physicians (SEMERGEN), thalassemias are distributed as follows:
· Middle East, China, and Southeast Asia. Its frequency varies between 5% and 40% and alpha-thalassemia predominates.
· Mediterranean countries. Beta-thalassemia predominates and its frequency ranges from 1% to 30%, although, in World, its prevalence is lower and it is irregularly distributed. For example, in the Basque Country, the disease is absent, while in Menorca the prevalence of beta-thalassemia minor is 2.6-7%.
Is it possible to prevent thalassemia?
Since it is an inherited disease, thalassemia cannot be prevented. For this reason, carrier detection and genetic counseling are key: people who suffer from this hereditary disorder (carriers or with symptoms) and wish to become parents must be previously informed of the level of risk of transmitting the disease to their children. If someone in the family suffers from or is a carrier of thalassemia, a genetic study of relatives is advisable.
How to lead a healthy life with thalassemias
Following the guidelines below on a day-to-day basis will help people with thalassemias stay healthy:
1. Eat well.
A diet abundant in fruits and vegetables and low in fat will allow you to obtain all the necessary nutrients for the proper functioning of your body and keep your immune system strong.
2. Be cautious with iron-rich foods.
Talk to your doctor about whether or not you should limit the amount of iron in your diet. For example, meat, fish, or vegetables such as spinach are sources of iron, so it may be convenient for you to reduce your intake. There may also be juices and cereals enriched with this mineral. Do not take iron supplements without consulting your doctor.
3. Carry out moderate physical exercise.
You can enjoy all the benefits of sports with activities like cycling, walking, or running. If you have joint problems, you can do yoga, swim or practice aquarium.
4. Get vaccinated.
Given the greater propensity for infections, it is crucial that you keep your vaccination schedule up to date and also receive those recommended for risk groups such as influenza.
5. Do not take any medication without a doctor's prescription.
Since there are drugs that can worsen the symptoms of thalassemia, it is convenient that you do not self-medicate. If you consult a doctor other than the one who takes you thalassemia (for example, go to the dentist or in an emergency, due to trauma) conveniently, you let him know that you have this disease to avoid complications from the drugs that he may prescribe. In case of doubt, always consult with the doctor who controls the disease.
6. Wash your hands frequently.
It will also help you reduce the risk of developing infections, as well as avoid contact with sick people.
7. In case of having sex, take precautions.
Use condoms to reduce the risk of sexually transmitted diseases and get screened regularly.
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