SICKLE CELL ANEMIA
What Are the Types of Sickle Cell Disease?
Hemoglobin is the protein in RBCs that carries oxygen. It is made up of two alpha chains and two beta chains. These are made by the alpha and beta genes. The four main types of sickle cell anemia are caused by different mutations in these genes.
Hemoglobin SS Disease
Hemoglobin SS disease is the most common type of sickle cell disease. It occurs when you inherit copies of the hemoglobin S gene from both parents. This forms hemoglobin known as Hb SS.
Hemoglobin SC Disease
Hemoglobin SC disease is the second most common type of sickle cell disease. It occurs when you inherit the Hb C gene from one parent and the Hb S gene from the other. Individuals with Hb SC have similar symptoms to individuals with Hb SS. However, the anemia is less severe.
Hemoglobin SB+ (Beta) Thalassemia
Hemoglobin SB+ (Beta) thalassemia affects beta globin gene production. The size of the red blood cell is reduced because less beta protein is made. If inherited with the Hb S gene, you will have Hemoglobin S Beta thalassemia.
What Causes Sickle Cell Anemia?
When both parents have a normal gene and an abnormal gene, each child has a 25 percent chance of inheriting two normal genes; a 50 percent chance of inheriting one normal gene and one abnormal gene; and a 25 percent chance of inheriting two abnormal genes.
People who inherit a sickle hemoglobin gene from one parent and a normal gene from the other parent have sickle cell trait. Their bodies make both sickle hemoglobin and normal hemoglobin.
People who have sickle cell trait usually have few, if any, symptoms and lead normal lives. However, some people may have medical complications.
People who inherit both sickle hemoglobin genes from both parents, develop Sickle Cell Disease. Their bodies make mostly sickle hemoglobin and normal haemoglobin also to a lesser percentage.
People who have sickle cell trait can pass the sickle hemoglobin gene to their children.
Who is at Risk for Sickle Cell Anemia?
Sickle cell anemia is most common in people whose families come from Africa, South or Central America (especially Panama), Caribbean islands, Mediterranean countries (such as Turkey, Greece, and Italy), India, and Saudi Arabia.
What are the Signs & Symptoms?
The signs and symptoms of sickle cell anemia vary. Some people have mild symptoms. Others have very severe symptoms and often are hospitalized for treatment.
Sickle cell anemia is present at birth, but many infants don't show any signs until after 4 months of age.
The most common signs and symptoms are linked to anemia and pain. Other signs and symptoms are linked to the disease's complications.
There are few signs called crisis, the patient usually presents with:
- Anemia: Anemia is a shortage of RBCs. Sickle cells is easily broken. This breaking apart of RBCs is called chronic hemolysis. RBCs generally live for about 120 days. Sickle cells live for a maximum of 10 to 20 days.
- Hand-foot syndrome (Veno-occlusive Crisis): Hand-Foot Syndrom eoccurs when sickle-shaped RBCs block blood vessels in the hands or feet. This causes the hands and feet to swell. It can also cause leg ulcers. Swollen hands and feet are often the first sign of sickle cell anemia in babies.
- Splenic Sequestration (Sequestration Crisis): Splenic sequestration is a blockage of the splenic vessels by sickle cells. It causes acute, painful enlargement of the spleen and drop in hemoglobin leading to sudden onset anemia. That is why parents are advised to palpate spleen at regular intervals and whenever they feel spleen is enlarging, they should immediately report to doctor.
- Acute Chest Syndrome: This is one life threatening complication of sickle cell disease. It is often predisposed by some infection. Patients develop marked respiratory distress & hypoxemia. It needs hospitalization and administration of IV fluids & IV antibiotics. Some patients may even need ventilator support.
- Stroke: Patients suffering from SCD may also develop stroke. This is due to damage caused to brain vasculature due to abnormal shape of red cells. These patients need regular red cell transfusion to keep sickle percentage below certain level to prevent further damage to brain vessels.
- Delayed Growth: Delayed growth often occurs in people with sickle cell anemia. Children are generally shorter but regain their height by adulthood. Sexual maturation may also be delayed. This happens because sickle cell RBCs can’t supply enough oxygen and nutrients.
- Severe pain in arms, back, abdomen and legs
- Fever
- Shortness of breath or difficulty in breathing
- Chest pain
- Severe infections
- Blood flow blockage in liver or spleen
- Pale skin
- Vision problems
- Kidney failure
Pulmonary Hypertension
How Is Sickle Cell Anemia Diagnosed?
- Complete Blood Count and PERIPHERAL Blood Smear: The characteristic finding of SCD is circulating sickle shaped red cells. Routine examination of the blood gives the diagnosis.
- Reticulocytosis i.e. increase in young red blood cells is almost always seen.
- Hemoglobin Electrophoresis: This is the cornerstone of diagnosis and is used to detect Hemoglobin S. HbA2 and often HbF are increased in patient with sickle cell-B thalassemia. Despite high level of HbF at birth, electrophoresis can detect HbS in the newborn.
Prenatal diagnosis may also be detected by examining the DNA from the chorionic villus biopsy or from the cells of amniocentesis.
How can Sickle Cell Anemia be prevented?
When the hemoglobin S gene is inherited from only one parent and a normal hemoglobin gene is inherited from the other, a person will have sickle cell trait. People with sickle cell trait are generally healthy. But people with sickle cell trait are carriers of a defective hemoglobin S gene. So, they can pass it on when they have a child. If the child’s other parent also has sickle cell trait or another abnormal hemoglobin gene (like thalassemia, hemoglobin C, hemoglobin D, hemoglobin E), that child has a chance of having SCD.
NOW it's possible to test for the genes your baby has inherited before giving birth. There are three ways of finding out if your unborn baby has sickle cell:
Chorionic villus sampling (CVS): Doctor takes a small sample of the placenta for DNA testing from 11 weeks of pregnancy.
Amniocentesis: A sample of the amniotic fluid surrounding your baby is tested, between weeks 16-20 of pregnancy.
Fetal blood sampling: Later in pregnancy, doctor can take some blood sample from the umbilical cord for testing.
Finding out baby has sickle cell disease can come as a shock. You may feel frightened and that you don't know what to expect. You may feel responsible for your baby's condition, too, but neither mother nor father is to blame.
These prenatal diagnosis are considered to be the only solution to prevent sickle cell disease all over the world. The procedure has been simplified by both obstetric and laboratory techniques, and can be carried out with safety in many countries, early enough to allow elective termination of pregnancy.
What about future pregnancies?
If a couple does decide to terminate their pregnancy after either an amniocentesis or a CVS test, this should not affect their fertility in future pregnancies. The couple may well wish to be referred to their genetic clinic to discuss the risk of an affected baby next time.
How is Sickle Cell Anemia Treated by Bone Marrow Transplant (BMT)?
A bone marrow transplant (BMT) is a procedure to replace damaged or destroyed bone marrow with healthy bone marrow stem cells. It is the soft, fatty tissue inside your bones which produces blood cells. Stem cells are immature cells in the bone marrow that give rise to all of your different blood cells. BMT procedure involves transplanting blood stem cells, which travel to the bone marrow where they produce new blood cells and promote growth of new marrow which in turn gives a normal & healthy life to the patient.
ALLOGENEIC BMT was first carried out in 1980 in a patient with Acute Leukemia who also had Sickle Cell Disease. Subseuqently, multicentric studies on BMT in Sickle Cell Disease has taken place in USA, France and Belgium.
This shows that 90% of the most severely affected patients with Sickle Cell Disease are cured with BMT from Matched Family Donors. However, very few patients with Sickle Cell Disease have a Matched Family Donor. The Unrelated Donor Registries rarely offer a full matched donor for these patients.
BMT in Sickle Cell Disease has produced the best results one can expect in any severe inherited disorder. Despite such encouraging results, BMT in Sickle Cell Disease had hit a roadblock due to lack of suitably matched donors.
But now, worldwide studies and Bone Marrow Transplants at our centre have shown that Haploidentical BMT can cure the majority of patients with Sickle Cell Disease without any severe complication.
Bone marrow transplant is the only curative option for sickle cell disease. Children who develop any of the below mentioned complications are candidates for BMT:
- Acute chest syndrome
- Stroke
- Frequent veno-occulsive episodes
- Poor access to medical care
- Frequent Pain Crisis
- Recurrent priapism
Initially patients who had matched sibling donors were considered to be candidates for bone marrow transplant but with improved techniques & strategies patients who lack matched sibling or related donor but need transplant can also be transplanted using half matched donors i.e., Haplo-identical Transplant.
Is bone marrow (stem cell) transplant the only treatment for sickle cell disease?
It is the only cure for sickle cell disease at this time. Results of many studies show that transplants from matched related donors offer about an 85- 90 percent chance of cure. Other temporary treatment choices are as follows. These treatments may lessen the complications of sickle cell disease, but they do not cure the disease.
- Antibiotics like penicillin may be given from 2 months of age to 5 years. They help prevent pneumonia in sickle cell patients.
- Pain medication is used to relieve the pain during a sickle crisis. You may need over-the-counter drugs or strong prescription pain medication like morphine.
- Hydroxyurea (Droxia, Hydrea) helps to increase production of fetal hemoglobin. It may reduce the number of blood transfusions.
- Immunizations can help prevent infections. Patients tend to have lower immunity.
- Surgery may be used to treat persistent painful erections.
- Blood transfusions can also treat sickle cell anemia. Packed red cells are removed from donated blood and given to patients. This improves transport of oxygen and nutrients.
- Supplemental oxygen is given through a mask. It makes breathing easier and improves oxygen levels in the blood.
- Home Care- There are things you can do at home to help your sickle cell symptoms.
- Heating pads and relaxation may help you deal with pain.
- Daily supplementation of folic acid and a healthy diet can help you make new RBCs. Fruits, vegetables, and whole-wheat grains are important.
- Increased water drinking can reduce chances of a sickle cell crisis.
- Avoiding extreme temperatures can also reduce the chance of a crisis. Exercising regularly and reducing stress may help as well.
Support groups can help you deal with this condition. Learn all you can about the disease.
What are the benefits of bone marrow (stem cell) transplant?
Bone marrow (stem cell) transplant is the only treatment available today that can cure sickle cell disease. If the transplant is successful, the patient is cured from sickle cell disease. For some Sickle Cell Anemia sufferers, the condition is debilitating.
A bone marrow transplant (BMT) is a procedure to replace damaged or destroyed bone marrow with healthy bone marrow stem cells. It is the soft, fatty tissue inside your bones which produces blood cells. Stem cells are immature cells in the bone marrow that give rise to all of your different blood cells. BMT procedure involves transplanting blood stem cells, which travel to the bone marrow where they produce new blood cells and promote growth of new marrow which in turn gives a normal & healthy life to the patient.
Our Bone Marrow Transplant Team offers a cure for the condition, and a chance to live a healthy, pain free life.
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