Haemoglobinopathies are abnormalities in the normal structure of the haemoglobin molecule. Normal haemoglobin is made up of four polypeptide chains each containing a haem group. HbA is the main adult form comprising two α chains and two β chains. Adults also have a minor haemoglobin HbA2, which makes up around 2% of the circulating haemoglobin and consists of two α chains and two δ chains. Abnormal haemoglobins result from:
· Abnormal globin chain production such as thalassaemia.
· Abnormal structure of the globin chain in sickle cell disease.