Sickle cell disease is a phenomenon where the red blood cells take the shape of a sickle or a crescent moon. It makes it difficult for these cells to move around easily through the blood vessels. This slows down or could even block the adequate flow of oxygen and blood to the different parts of the body causing health problems.
In adults the haemoglobin is of three variants
- HbA: This involves a significant portion of 95 to 98 per cent
- HbA2: This involves 1.5 per cent to 3.5 per cent
- HbF: This involves less than 2 per cent and is age dependent
Haemoglobin is a tetrameric protein composed of two pairs of globin chains each with a heme group.
In sickle cell disease or sickle cell anaemia, there is a point mutation of the beta-globin chain, thus impacting in replacement of glutamic acid to valine residue in the beta-globin which causes sickling of the RBC. The type of haemoglobin responsible for sickle cell disease is HbS. It leads to micro- vasculature obstruction and tissue damage.
Sickle cell disease affects millions of people globally. The most common ways to treat this disease is through blood transfusions and bone marrow transplant.
Sickle cell disease is an inherited disorder causing red blood cell distortion, destruction. The inheritance is homozygous for sickle cell disease if transferred from both the parents.
If inheritance from one parent impacts in the milder form, it is called sickle cell trait (Hb AS). The HbSS molecules (RBC) build up into polymers when deoxygenated, yet giving rise to chronic haemodialysis, microvascular occlusions at the same time tissue damage.
During deoxygenation, the cytoplasm in red blood cell/RBC turns from free-flowing liquid into viscous gel and assemble themselves into long needle-like fibres within RBC and produce a sickle shape.
Young patients will show signs of the following:
- Jaundice (due to RBC destruction)
- Painful bones (due to hypoxia caused by microvascular occlusion due to haemolysis)
- Fever, cough and chest pain if the lungs are involved
- Erectile dysfunction in males after puberty
- Retinopathy, loss of vision and blindness
- Shock due to rapid splenic enlargement
- Worsening of anaemia and aplasia if there is an infection by a virus, especially parvovirus B19
- The patient loses the ability to concentrate urine and thus becomes dehydrated and the vicious cycle continues