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 molecular chain, alpha and beta. Production of these chains are controlled by genes. An inherited defect in one of these genes results in thalassaemia.
Alpha – Thalassaemia
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-thalassaemia according to the number of defective genes present:-
a) 1 defective gene – silent carrier
Healthy, no anaemia.
b) 2 defective genes – Alpha-thalassaemia trait
Healthy, may be mildly anaemic with red blood cell abnormality
c) 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.
d) 4 defective genes – Hydrops fetails
Incompatible with life, results in foetal death before birth.
The above disorders are hereditary especially in the case of first 2 groups where symptoms are not apparent and patients are generally not aware of the disorder until or unless they go through blood examinations.
Beta – Thalassaemia
There are 2 main types of disorders from defective synthesis of the beta chain.
a) 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.
This is in the form of homozygous or complete inheritance and is usually a severe disorder, though 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 body tissues and subsequently causes damage to the heart, liver and other organs. Death frequently occurs during adolescence.
Diagnosis – As symptoms are not apparent in most thalassaemia patients other than those with thalassaemia major. Diagnosis is 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 thalassaemia minor require no treatment apart from receiving folic acid supplement and to avoid oxidant drugs in cases of patients with HbH disease. However, thalassaemia 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 spleen may be required when blood transfusion requirements become too excessive. The only known method to cure beta-thalassaemia major is by hone marrow transplantation. The success rate may exceed 80%
Preventing – The incidence of thalassaemia can be reduced if carriers and people with thalassaemia 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 unfortunate sufferers of thalassaemia, you are advised to go for a blood test to determine your condition.
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