Haemoglobin disorders or haemoglobinopathies are a group of conditions affecting the molecule haemoglobin which is contained in the red blood cells. The globin part of haemoglobin is a protein that consists of the alpha (α) and beta (β) parts or chains, which are produced by the α-globin genes and β-globin genes. These genes are found on chromosomes 16 and 11 respectively.
Any disturbance of this structure of the haemoglobin molecule, reduces the capacity of the haemoglobin to carry oxygen to the tissues, but also disturbs the whole structure of the red blood cell containing the haemoglobin. There are various abnormalities which can arise due to changes (mutations) in the genes that regulate the production of these proteins.
Mutations can cause reduced production of the proteins, either the α-globin chains or the β- chains. The resultant disorders are known as the thalassaemias.
Other mutations may allow production of adequate quantities of the proteins but alter their structure. These are known as haemoglobin variants and they alter the function of the whole haemoglobin molecule. The most common of these are the sickle cell mutation (HbS) and the haemoglobin E (HbE) mutation. There are many others less common and some very rare.