Sickle Cell Anemia
Problem
Sickle cell anemia is an autosomal recessive disease where the body produces stiff and sticky red blood cells that become sickle shaped in a low oxygen levels. They cause blockages in blood vessels causing severe pain and even organ damage. The body also suffers from anemia, since sickle cells only survive for 10 to 20 days and the bone marrow is unable to make red blood cells fast enough to replace the old ones.
Cause Normal Hemoglobin Beta Gene Sequence
AA= Normal person CTG ACT CCT GAG AAG AAG TCT
SA= Sickle cell trait Abnormal Hemoglobin Beta Gene Sequence
SS= Sickle cell anemia CTG ACT CCT GTG AAG AAG TCT
Hemoglobin is composed of two α-globin and two β-globin chains. Hemoglobin S is a result of a point mutation in the β-globin gene located on chromosome 11 (11p15.5 ). Adenine is converted into thymine, resulting in Valine replacing Glutamic acid. This now codes for a mutant β-globin. Two α-globins and two mutant β-globin associate, to form hemoglobin S. The change into Valine creates a hydrophobic region on the surface of the β-globin that sticks to the hydrophobic region on the hemoglobin molecule next to it, in low oxygen levels. Polymerization of hemoglobin S molecules forms rigid fibers creating the sickle shape of the red blood cells.
Statistics
Sickle cell anemia is found in 1 of 600 African Americans. It is most common among Africans, Indians and other areas where malaria is present. Having the sickle cell trait is actually beneficial to patients with malaria
Symptoms
Symptoms appear after 6 months of age when fetal hemoglobin is gone, but when they do, they include:
Hand-foot syndrome- Blockages in blood vessels preventing blood from flowing in those areas and causes swelling.
Fatigue, paleness, and shortness of breath- Due to low red blood cell count.
Eye problems- Blockages can damage retina causing vision problems and,even blindness.
Jaundice-Due to the rapid death rate of sickle cells, there is an accumulation of bilirubin (released when red blood breaks down) in the body, resulting in jaundice.
Frequent infections- The damaged spleen can’t destroy bacteria so patients are vulnerable to infections.
Crises- Crises are episodes of pain that occur due to an obstruction caused by sickle cells.
Leg ulcers- Leg ulcers typically occur towards the lower end of the leg
Delayed growth- The reduction of healthy red blood cells results in a shortage of oxygen and nutrients for the body’s cells.
Diagnostic tests
Hemoglobin electrophoresis is a blood test that measures the different types of hemoglobin in your blood. Healthy adults will have high levels of hemoglobin A or A2 while patients with sickle cell anemia will have a significant level of hemoglobin S.
Treatment
To manage symptoms, patients take pain medications as well as adequate liquid intake for crisis. Folic acid is taken to promote the production of red blood cells reducing the effects of anemia. Antibiotics are taken to help prevent infections. Hydroxyurea increases the amount of fetal hemoglobin to reduce the frequency of crises.
Cure
Currently, the only cure is receiving a bone marrow transplant. However, there are risk involved, so it is only suggested for those with a severe form of the disease. The patient's bone marrow is first destroyed using radiation and replaced with a donor’s bone marrow. It’ll take a few weeks for the new bone marrow to grow to a sufficient size. During this time period, the patient is susceptible to infections with a chance of possible death.