Thalassaemia

Thalassaemia is an inherited form of anaemia with a wide spectrum of severity, varying from the perfectly healthy to the severely anaemia and sometimes stillborn.

Normal red blood cells contain haemoglobin which has 2 main types of melecular chain, alpha and beta. Production of these chains are controlled by genes. An inherited defect in one of these genes results in thalassaemia.

There are 2 main types of Thallassaemia :


(A) ALPHA-THALLASSAEMIA

In this group, there is defective synthesis of the alpha chain. As 4 genes control the formation of this chain, there are 4 types of alpha-thallassaemia according to the number of defective genes present :-

1. 1 defective gene - silient carrier
   Healthy, no anaemia.
   
   
2. 2 defective genes - Alpha-thallassaemia trait
   Healthy, may be mildly anaemia with red blood cell abnormally.
   
   
3. 3 defective genes - Hemoglobin H Disease
   Varies in severity, some may have no disability whilst others may develop anaemia which can be aggravated by certain infections and drugs. Disorder includes bone deformities, enlarged liver and spleen. However, it is usual for affected persons to live a normal life span.
   
   
4. 4 defective genes - Hydrops fetails
   Incompatible with life, results in fetal death before birth.
   
   

The above disorders are hereditary especially in the case of first 2 groups where symptons are not apparent and patients are generally not aware of the disorder until or unless they go through blood examinations.


(B) BETA-THALASSAEMIA

There are 2 main types of disorders from defective synthesis of the beta chain.

1. Beta-thalassaemia minor
   This is in the form of heterozygus or partial inheritance. There is no abnormal physical findings apart from mild anaemia. In most cases, patients become aware of their conditions only after having gone through blood examinations or upon the birth of a child.
   
   
2. Beta-thallasaemia major
   This is in the form of homozygus or complete inheritance, and is usually a severe disorder, through the degree of severity varies widely. Sufferers usually develop anaemia by the third month after birth, with enlargement of liver and spleen and followed by bone deformities and retardation of growth. The anaemia progressively becomes worse, prompting the need for regular blood transfusions. This causes excessive iron deposition in the body tissue and subsequently causes damage to the heart, liver and other organs. Death frequently occurs during adolescence.
   
   

DIAGNOSIS
As symptoms are not apparent in most thallasaemia patients other than those with thallasaemia major, diagnosis in only through blood tests.

Examination of the red blood cells can reveal certain abnormalities that indicate the presence of this disorder. The diagnosis is confirmed by a test called Haemoglobin Electrophoresis.



TREATMENT
People with thallasaemia minor require no treatment apart from receiving folic acid supplement and to avoid oxidant drugs in cases of patients with HbH disease. However, thallasaemia major sufferers often require regular blood transfusions to survive. This may cause an overload of iron in the body to toxic level, making chelation therapy to reduce absorption of iron necessary. Surgery to remove the speeln may be required when blood transfusion requirements become too excessive. The only known method to cure beta-thallasaemia major is by bone marrow transplantation. The success rate may exceed 80%.


PREVENTING
The incidence of thallasaemia can be reduced if carriers and people with thallasaemia trait are aware of their conditions and avoid marrying each other. If you have reasons to believe that any of your immediate family members (parents, siblings, children) could be an unfortunate sufferers of thallasaemia, you are advised to go for a blood test to determine your condition.

Couples who suspect that they could be at risk can now undergo early intrauterine diagnosis of thallasaemia, and where appropriate, termination of pregnancy.

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