Last edited 07/2018 and last reviewed 04/2019

The thalassaemias are a group of recessively autosomal inherited disorders in globin chain production (1).

  • it is charcterised by decreased or absence of  either the alpha or the beta chains of normal adult human haemoglobin molecule, resulting in alpha and beta thalassaemia respectively (1).
    • alpha thalassaemia major is incompatible with life, beta thalassaemia major results in severe anaemia.(2)

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. (3) There are other less serious thalassaemia disorders which can be detected by the screening programme

Classification of the disease is according to the clinical severity (phenotype) or type of mutation (genotype) (1).


  • thalassaemias are the commonest genetic disorders in the world - 150 million people 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