Sickle cell anaemia is a disorder of the blood caused by an inherited abnormal hemoglobin (an oxygen-carrying protein within the red blood cells). The abnormal hemoglobin causes distorted (sickled) red blood cells.The sickled red blood cells are fragile and prone to rupture. When the number of red blood cells decreases from rupture, anaemia is the result.
Figure 1: Difference between normal red blood cells and sickle cells
this sickle cells will have difficulty to pass through the small blood vessels. When sickle-shaped cells block small blood vessels, less blood can reach that part of the body. Tissue that does not receive a normal blood flow eventually becomes damaged. this is the complications of the sickle cell anaemia. currently, there are no any cure for sickle cell anaemia.
Figure 2: sickle cells blocking the blood vessels
People with sickle cell conditions make a different form of hemoglobin A called hemoglobin S (S stands for sickle). Red blood cells containing mostly hemoglobin S do not live as long as normal red blood cells (normally about 16 days). They also become stiff, distorted in shape and have difficulty passing through the body’s small blood vessels. When sickle-shaped cells block small blood vessels, less blood can reach that part of the body. Tissue that does not receive a normal blood flow eventually becomes damaged. This is what causes the complications of sickle cell disease. There are several types of sickle cell disease. The most common are: Sickle Cell Anemia (SS), Sickle-Hemoglobin C Disease (SC), Sickle Beta-Plus Thalassemia and Sickle Beta-Zero Thalassemia. like our hair color, blood type, eye color and other physical traits, this sickle cells also inherited from our parents.. how it is actually inherited from the parents???
Sickle cell anemia is inherited as an autosomal (meaning that the gene is not linked to a sex chromosome) recessive condition whereas sickle cell trait is inherited as an autosomal dominant trait. This means that the gene can be passed on from a parent carrying it to male and female children. In order for sickle cell anemia to occur, a sickle cell gene must be inherited from both the mother and the father, so that the child has two sickle cell genes. The inheritance of just one sickle gene is called sickle cell trait or the "carrier" state. Sickle cell trait does not cause sickle cell anemia. Persons with sickle cell trait usually do not have many symptoms of disease and have normal hospitalization rates and life expectancies. which means, the carriers of sickle cell genes will never suffer from the disease...
Figure 3: the inheritence of sickle cell anaemia
Sickling of the red blood cells in patients with sickle cell anaemia results in cells of abnormal shape and flexibility. The sickling is promoted by conditions which are associated with low oxygen levels, increased acidity, or low volume (dehydration) of the blood. These conditions can occur as a result of injury to the body's tissues, dehydrating states, or anesthesia. Even certain organs are predisposed to lower oxygen levels or acidity, such as when blood moves slowly through the spleen, liver, or kidney. Also, organs with particularly high metabolism rates (such as the brain, muscles, and the placenta in a pregnant woman with sickle cell anaemia) promote sickling by extracting more oxygen from the blood. These conditions make these organs susceptible to injury from sickle cell anaemia.
figure 4: blockage of the blood vessels
blood check-up can reveal whetehr someone is having sickle cell anaemia or not. the blood taken must undergo a lab technique known as Haemoglobin Electrophoresis. this technique will determine the type of haemoglobin the person has. The hemoglobin electrophoresis test precisely identifies the hemoglobins in the blood by separating them. The separation of the different hemoglobins is possible because of the unique electrical charges they each have on their protein surfaces, causing them each to move characteristically in an electrical field as tested in the laboratory. there are many symptomps for who suffers with this sickle cell anaemia. the major symptoms of sickle cell anaemia will be :-
•Fatigue and Anemia
•Pain Crises
•Dactylitis (swelling and inflammation of the hands and/or feet) and Arthritis
•Bacterial Infections
•Splenic Sequestration (sudden pooling of blood in the spleen) and Liver Congestion
•Lung and Heart Injury
•Leg Ulcers
•Aseptic Necrosis and Bone Infarcts (death of portions of bone)
•Eye Damage
Virtually all of the major symptoms of sickle cell anaemia are the direct result of the abnormally shaped, sickled red blood cells blocking the flow of blood that circulates through the tissues of the body. The tissues with impaired circulation suffer damage from lack of oxygen. Damage to tissues and organs of the body can cause severe disability in patients with sickle cell anaemia. The patients endure episodes of intermittent "crises" of variable frequency and severity, depending on the degree of organ involvement. most of the features occurs in certain group of age. Sickle cell anaemia usually first presents symptoms in the first year of life. Infants and younger children can suffer with fever, abdominal pain, pneumococcal bacterial infections, painful swellings of the hands and feet (dactylitis), and splenic sequestration. Adolescents and young adults more commonly develop leg ulcers, aseptic necrosis, and eye damage. Symptoms in adult typically are intermittent pain episodes due to injury of bone, muscle, or internal organs.
Affected infants do not develop symptoms in the first few months of life because the hemoglobin produced by the developing fetus (fetal hemoglobin) protects the red blood cells from sickling. This fetal hemoglobin is absent in the red blood cells that are produced after birth so that by 5 months of age, the sickling of the red blood cells is prominent and symptoms begin.
figure 5: the symptoms of sickle cell anaemia
The life expectancy of persons with sickle cell anemia is reduced. Some patients, however, can remain without symptoms for years, while others do not survive infancy or early childhood. Nevertheless, with optimal management patients can now survive beyond the fourth decade. Most patients suffer intermittent pain crises, fatigue, bacterial infections, and progressive tissue and organ damage. Impaired growth and development is the end result of the physical and emotional trauma that is endured by children with sickle cell anemia. Causes of death include bacterial infection (the most common cause), stroke or bleeding into the brain, and kidney, heart, or liver failure. The risk of bacterial infections does diminish after three years of age. Nevertheless, bacterial infections are the most common cause of death at any age. Therefore, any signs of infection in a person with sickle cell anemia must be reviewed with a doctor to prevent damage and save lives. Interestingly, the sickle cell gene somewhat protects against malaria infection. This makes those with sickle cell trait (gene carriers) at least partially resistant to malaria. Furthermore, the geographic distribution of the sickle cell gene is similar to that of malaria infection. Sickle cell anemia is a lethal condition that threatens life. But there may be a selective advantage to being a sickle cell carrier (trait) if the person resides in an area of the world where malaria is very common. though there are no any cure for sickle cell anaemia patients, but there are certain treatments that can help all those atients to cope up with the disease. Health maintenance for patients with sickle cell disease starts with early diagnosis, preferably in the newborn period and includes penicillin prophylaxis, vaccination against pneumococcus bacteria and folic acid supplementation. Treatment of complications often includes antibiotics, pain management, intravenous fluids, blood transfusion and surgery all backed by psychosocial support. Like all patients with chronic disease patients are best managed in a comprehensive multi-disciplinary program of care. Blood transfusions help benefit sickle cell disease patients by reducing recurrent pain crises, risk of stroke and other complications. Because red blood cells contain iron, and there is no natural way for the body to eliminate it, patients who receive repeated blood transfusions can accumulate iron in the body until it reaches toxic levels. It is important to remove excess iron from the body, because it can gather in the heart, liver, and other organs and may lead to organ damage. Treatments are available to eliminate iron overload.
figure 6: Organs may be affected by iron overload
Recent research is examining further ways to promote the development of the fetal hemoglobin that delays the development of sickle cell in the newborn. Bone marrow transplantation is being used for patients with severe sickle cell anemia who have a genetically identical sibling that can offer the transplant marrow. Future treatments may involve genetic engineering where cures might be achieved. Finally, genetic counseling can be helpful for parents and families to prevent sickle cell anaemia.
References
•Aplatt, 2010. Sickle Cell Information Center [Online]. Available from: [Accessed 11 July 2010]
•Pearson H (Aug 1977). "Sickle cell anaemia and severe infections due to encapsulated bacteria" (Free full text). J Infect Dis 136 Suppl: S25–30. ISSN 0022-1899. PMID 330779 : [Accessed on 12 July 2010]
•Powars DR, Elliott-Mills DD, Chan L, et al. (Oct 1991). "Chronic renal failure in sickle cell disease: risk factors, clinical course, and mortality". Ann. Intern. Med. 115 (8): 614–20. ISSN 0003-4819. PMID 1892333 : [Accessed on 12 July 2010]
