Haemoglobin disorders or haemoglobinopathies are a group of conditions affecting the 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, such as α-thalassaemia, and β-chain (β-globin gene) diseases, such as β-thalassaemia major and sickle cell disease.
These genes are found on chromosomes 16 and 11 respectively, producing equal amounts of α and β chains respectively which match together to α2β2 to produce the normal adult haemoglobin (HbA, α2β2).
The major alpha (α-) thalassaemias are a group of inherited thalassaemias with varying clinical severity. The major a-thalassaemias are (1) HbH disease, (2) α-thalassaemia Hydrops Foetalis, (3) (=) Hb Bart’s Hydrops Foetalis.
Beta thalassaemia is the most severe form of thalassaemia. Patients with β-thalassaemia major cannot make normal adult haemoglobin and as a consequence cannot produce normal red blood cells (RBCs)
Sickle cell disease
SCD is caused by a haemoglobin defect, known as Haemoglobin S. In SCD, the bone marrow cannot produce enough healthy red cells. The red cells produced look like sickles, are not flexible and can stick on vessels’ walls causing blood clots and preventing oxygen from reaching the body tissues.
Transfusion Dependent Thalassaemias is a term used to label patients who do not need regular blood transfusions for survival but may need occasional or even frequent transfusions for defined periods of time.
At present, thalassemia can be cured in some children by bone marrow transplant. Gene therapy is being studied as a potential cure for some patients.
Clinical trials and updates
Clinical trials are experiments or observations carried out in clinical research, designed to answer specific questions about new treatments (such as novel vaccines, drugs etc.) for further study and comparison.