The information you are going to get from this Article are:
1. What is Thalassemia and when does it occur?
2. Anatomy of Hemoglobin.
3. Function of Hemoglobin.
4. Types of Thalassemia.
5. Alpha Thalassemia and its types.
• Silent Carrier.
• Trait or Carrier.
• Hb H Disease.
• Bart’s Syndrome.
If anyone has thalassemia, it means that there is a lack of an important protein called hemoglobin (a protein that helps the red blood cells to carry oxygen) in the blood of one’s body. Lack of hemoglobin destroys the red blood cells. Thalassemia only occurs when both the parents of the thalassemia patient are carriers (both the parents have one mutated gene). Due to this reason, thalassemia is also called an inherited blood disorder.
Anatomy of Hemoglobin
The bone marrow in the bones are is responsible for producing red blood cells, white blood cells, and platelets. Billions of red blood cells are made in our body per day. Hemoglobin is a protein that is present inside the red blood cells. Hemoglobins are made up of amino acids (molecules that produce proteins). Each hemoglobin consists of 4 polypeptide chains (when amino acids connect by peptide bonds, they form polypeptide chains). Two are alpha chains, each having 141 amino acids and two are beta chains, each containing 146 amino acids. Every hemoglobin contains Four heme groups and each heme is composed of one iron atom. In adults’ hemoglobin or HbA, there are alpha and beta chains of hemoglobin. The fetal (before birth) hemoglobin or HbF contains two alpha chains and two gamma chains. These gamma chains changed into beta chains after birth.
Function of Hemoglobin
Hemoglobin serves a very important function in the body. The iron present in hemoglobin helps it to bind the oxygen and transfer it from the lungs to the tissues of the body. Carbon dioxide is also released with the help of hemoglobin. The red color of blood is also due to hemoglobin.
Types of Thalassemia
There are two types of thalassemia alpha and beta-thalassemia. Both of these types have their minor and major forms.
1. Alpha Thalassemia
Thalassemia occurs due to a mutation in the genes that make hemoglobin. Alpha thalassemia is resulted due to the change in the genes that make an alpha chain. An alpha chain is formed when two genes are inherited from each parent to the child. Altogether, four genes are used to make an alpha chain. These genes are nearly present in the area of chromosome 16 and each chromatid has two genes. Alpha thalassemia is caused when a change occurs in these genes. There are four types of alpha thalassemia.
• Alpha Thalassemia Silent Carrier
When there is only one gene in the alpha chain is missing or damaged, then it will not cause any symptoms. Hemoglobin will work properly and the person will live a normal life. Due to having no signs, you can only detect a silent carrier by DNA test. A silent carrier needs no medical treatment but can pass the disorder to the offspring.
• Alpha Thalassemia Carrier or Trait
When two genes out of four are destroyed, the patient may have mild anemia or no symptoms. The patient can still live a healthy life but inherit the disorder in the next generation. For diagnosing DNA test is needed. The patient with an alpha thalassemia carrier may not need any treatment.
• Hemoglobin H Disease
This condition occurs due to the absence or destruction of three alpha genes and left behind only one normal gene. The reduction of alpha chains causes the production of tetramers of beta chains which results in HbH disease. The symptoms of having HbH are mild or severe anemia, jaundice (paleness of skin and yellow eyes), shortness of breath, poor growth, leg ulcer, etc. HbH disease can be diagnosed by electrophoresis test, microcytosis, etc. The treatment of HbH is given according to the severity of the condition. The doctor may prescribe doses of folic acid, some medicines to decrease the amount of extra iron in the body. The patient may need a blood transfusion, removal of the spleen by surgery, etc.
• Hb Bart Syndrome
This condition is also known as alpha thalassemia major. It is the most severe form of alpha thalassemia in which all of the four genes of the alpha chain are missing. Due to the damaged alpha genes, an excessive number of gamma genes are produced. The gamma genes have more affinity (liking) for oxygen than the alpha genes, because of which a very less quantity of oxygen is delivered to the tissues of the body. Bart’s syndrome only affects males because it is an X-linked disorder. We know that a boy is having X and Y chromosomes and a Y chromosome is smaller than the X chromosome. A girl has two X chromosomes. This disorder only occurs in males due to mutation in a gene called TAZ (Tafazzin). This gene occurs at some point on the X chromosome and does not have an adjusting area on the Y chromosome due to its small size. So, whenever in females a changed TAZ gene of one X chromosome is inherited, the other inherited normal TAZ gene of the other X chromosome provides enough function to avoid the expression of the disorder. The female then becomes a carrier without any symptoms. But, this does not happen in males because of two different chromosomes. Because a male is having only one X chromosome, and if a mutated TAZ gene is inherited the male will be affected with Bart’s disorder. Because a male is having only one X chromosome, and if a mutated TAZ gene is inherited the male will be affected with Bart’s disorder. Other complications that occur due to Bart’s syndrome are a weakness of the heart, weak muscles, poor growth, loss of white blood cells, etc. There is not a specific treatment for Bart’s disease. The doctor will prescribe the medicine or drug according to the symptoms a patient has.