Published Online: 19 APR 2010
Copyright © 2001 John Wiley & Sons, Ltd. All rights reserved.
How to Cite
Weatherall, D. J. 2010. Thalassaemias. eLS. .
- Published Online: 19 APR 2010
The thalassaemias are the commonest genetic disorders in humans and present an increasing public health problem in the tropical countries in which they occur at a high frequency. There are many different forms of thalassaemia, all resulting from mutations of the genes which are responsible for regulating the structure and synthesis of haemoglobin. These diseases are all transmitted in a Mendelian fashion; parents, who are symptomless carriers, each pass on a defective gene to a severely affected offspring. The extremely high frequency of these diseases reflects natural selection whereby symptomless carriers are more resistant to different forms of malaria. A better understanding of the genetic basis of these diseases has led to improvements in their prevention and symptomatic treatment.
The haemoglobinopathies, thalassaemia and sickle cell disease, are by far the commonest genetic disorders.
These diseases have reached their high frequency mainly due to natural selection through heterozygote protection against malaria.
Thalassaemias consist of several different disorders, each due to many different underlying mutations of the globin genes.
All the severe forms of thalassaemia show a remarkable clinical variability which reflects both genetic modifiers, adaption to anaemia and the environment.
All the different forms of thalassaemia can be identified in fetal life and hence prenatal diagnosis is possible.
A cure of thalassaemia is only possible by bone marrow transplantation when suitable donors are available.
Most serious forms of thalassaemia are amenable to symptomatic treatment with transfusion and drugs to remove excess iron.