What Is Sickle Cell Disease
Sickle cell disease is a group of inherited blood disorders in which the body produces abnormally-shaped red blood cells that look like crescent moons or sickles. Sickle cells have a shorter-than-normal life span; their premature destruction results in shortage of red cells, known as anemia.
Signs of Anemia
Signs of anemia include shortness of breath, fatigue, and delayed growth in children. Unlike normal red cells which are pliant, sickle cells are rigid and also sticky. They may clump together and stick to the walls of blood vessels, causing obstruction in small vessels and subsequent reduced oxygen supply to various organs. This happens repeatedly and manifests as periodic episodes of pain, called crises, which can last hours to days, and may result in organ damage, especially in the eyes, lungs, kidneys, bones and brain. The spleen has to handle large numbers of dead red cells and becomes enlarged and fibrous, its immune function declines, making the body more vulnerable to infections.
In an attempt to compensate for blood cell loss, the bone marrow tries to produce more cells and grows larger, causing bones to weaken.
Other Signs of Sickle Cell Disease
Other signs include jaundice, a result of rapid destruction of heme( a part of hemoglobin).
Hemoglobin is the major component of red blood cells and is responsible for oxygen transport.
There are 2 major forms of hemoglobin – hemoglobin A( adult, normal) and hemoglobin S( sickle).
Hemoglobin S has the tendency to form polymers under low oxygen conditions. This process is called sickling, or gelation.
Apart from oxygen tension, the presence of other hemoglobins also seems to affect the sickling process. Normal adult hemoglobin inhibits sickling and this explains why heterozygous parents, who produce both mutated hemoglobin S and normal hemoglobin A, do not usually develop the disease.
Infants (less than 6months) with sickle cell disease don’t usually have crisis
Fetal hemoglobin F, which has 2 gamma chains in place of 2 beta chains, also suppresses sickling. Infants born with the condition seem to benefit from high levels of fetal hemoglobin in the first few months of life: they do not develop symptoms until the age of 6 months or so, when fetal hemoglobin levels drop.
Cure for Sickle Cell Disease
Bone marrow transplantation is currently the only known cure for sickle cell disease. It involves replacing the diseased stem cells in the bone marrow with healthy cells from an eligible donor, usually a relative.
The procedure however is complex and finding a suitable donor can be difficult.
Other Treatment
In most cases, treatments aim to avoid crises, relieve symptoms and prevent complications. These include:
– Prophylactic antibiotics, vaccinations to prevent infections,
– Pain medication to relieve pain,
– Drugs that promote formation of fetal hemoglobin, to suppress sickling,
– Periodic blood transfusions, to reduce anemia and prevent crises,
– and early detection and treatment for complications when these occur.
Prevention
Premarital/prenatal counselling and testing for HB genotype of intending parents is very important.
This is to ensure genotype compatibility of the parents and prevents giving birth to offsprings with sickle cell disease.
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