This section is dedicated to beta (β-) thalassaemia syndromes of which β-thalassaemia major, also known as Mediterranean anaemia or Cooley’s Anaemia, is the clinically most severe one.
THE MAJOR BETA (β-) THALASSAEMIA SYNDROMES ARE:
- β-thalassaemia major
- β-thalassaemia intermedia
- Other rare thalassaemias
Many diseases in humans are caused by abnormalities in the blood and these are categorized according to the component of the blood which is affected: white cell diseases, platelet diseases and red cell diseases.
Haemoglobin disorders or haemoglobinopathies are a group of conditions affecting human blood – more specifically an important substance or protein called haemoglobin contained in the red blood cells, hence the name haemoglobin disorders or haemoglobinopathies.
Haemoglobin is a protein that consists of the alpha (α) and beta (β) parts or chains and which are in turn produced by the α-globin genes and β-globin genes respectively. Hence the diseases caused by haemoglobin abnormality either with regards to its production or its structure are divided into α-chain diseases (or α-globin gene) diseases and β-chain (β-globin gene) diseases. These genes are found on chromosomes 16 and 11 respectively.
Patients with β-thalassaemia major, the most severe form of thalassaemia, cannot make normal adult haemoglobin, which is made up of equal numbers of α- and β-chains, and as a consequence cannot produce normal red blood cells (RBCs). In these individuals, i.e. those with β-thalassaemia major, each red blood cell contains much less haemoglobin, because the β-globin genes are not working or functioning properly and thus do not or produce very small amounts of β-chains. Consequently, there are far fewer red cells than the normal range. This causes anaemia, which is severe in these patients, as shown in the figure below on the right hand side.