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The thalassaemias are genetic disorders in globin chain production. The production
of either the alpha or the beta chains of haemoglobin may be reduced, resulting
in alpha and beta thalassaemia respectively. Alpha thalassaemia Major is incompatible
with life. Beta thalassaemia Major results in severe anaemia.
o Inheritance of an affected gene from both parents results in a disorder and
inheritance of only one affected gene results in a healthy carrier, sometimes
called a trait. There are other less serious thalassaemia disorders which can
be detected by the screening programme
The thalassaemias are the commonest genetic disorders in the world - 214.000
people in the UK carry the beta-thalassaemia gene - and occur in a very high
frequency in a tropical belt extending from Africa, throughout the Mediterranean
region, the Middle East, the Indian subcontinent, and throughout South West
Asia. They occur sporadically in every population. It is possible that the heterozygote
state provides protection against falciparum malaria, thus explaining its high
carrier rate in certain populations.
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