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Is Sickle Cell Disease a Genetic Defense Against COVID-19?
Dr. Msaouel answers questions from the Sickle Cell community. If the disease or trait evolved as a defense against Malaria, does the reported effectiveness of anti-malaria drugs like hydroxychloroquine (Plaquenil) mean that sickle cell patients have natural resistance to the novel coronavirus, COVID-19?
People with sickle cell disease (SCD) start to have signs of the disease during the first year of life, usually around 5 months of age. Symptoms and complications of SCD are different for each person and can range from mild to severe.
The reason that infants don’t show symptoms at birth is because baby or fetal hemoglobin protects the red blood cells from sickling. When the infant is around 4 to 5 months of age, the baby or fetal hemoglobin is replaced by sickle hemoglobin and the cells begin to sickle.
SCD is a disease that worsens over time. Treatments are available that can prevent complications and lengthen the lives of those who have this condition. These treatment options can be different for each person depending on the symptoms and severity.
Swelling in the hands and feet usually is the first symptom of SCD. This swelling, often along with a fever, is caused by the sickle cells getting stuck in the blood vessels and blocking the flow of blood in and out of the hands and feet.
Pain “Episode” or “Crisis”
Pain is the most common complication of SCD, and the number 1 reason that people with SCD go to the emergency room or hospital. When sickle cells travel through small blood vessels, they can get stuck and clog the blood flow. This causes pain that can start suddenly, be mild to severe, and can last for any length of time.
There are simple steps that people with SCD can take to help prevent and reduce the number of pain crises, including the following:
Drink plenty of water.
Try not to get too hot or too cold.
Try to avoid places or situations that cause exposure to high altitudes (for example, flying, mountain climbing, or cities with a high altitude).
Try to avoid places or situations with exposure to low oxygen levels (for example, mountain climbing or exercising extremely hard, such as in military boot camp or when training for an athletic competition).
Adults with severe SCD can take a medicine called hydroxyurea to help reduce the number of pain crises.
People taking hydroxyurea are checked often by a doctor to prevent complications, including an increased risk of infections.
Research shows that babies and children with SCD can also benefit from hydroxyurea therapy.
Anemia is a very common complication of SCD.
With SCD, the red blood cells die early. This means there are not enough healthy red blood cells to carry oxygen throughout the body. When this happens, a person might have:
Dizziness and lightheadedness
A fast heart rate
Pale skin color
Jaundice (yellow color to the skin and whites of the eyes)
People with SCD, especially infants and children, are more at risk for infections, especially those due to bacteria with capsules because of damage to the spleen. Pneumonia is a leading cause of death in infants and young children with SCD.
Acute Chest Syndrome
This can be life-threatening and should be treated in a hospital. Symptoms and signs are similar to pneumonia. Signs and symptoms include chest pain, coughing, difficulty breathing, and fever.
Adults with severe SCD can take a medicine called hydroxyurea to help prevent acute chest syndrome. People taking hydroxyurea are monitored closely with regular blood testing and dose adjustments to prevent complications.
A person who is on bed rest or has recently had surgery can use an incentive spirometer, also called “blow bottle,” to help prevent acute chest syndrome.
This can be life-threatening and should be treated in a hospital. It happens when a large number of sickle cells get trapped in the spleen and cause it to suddenly get large. Symptoms include sudden weakness, pale lips, fast breathing, extreme thirst, abdominal (belly) pain on the left side of body, and fast heartbeat.
Parents of a child with SCD should learn how to feel and measure the size of their child’s spleen and seek help if the spleen is enlarged.
For those who have had a very severe, life-threatening episode of splenic sequestration or who have had many episodes in the past, it might be necessary to have regular blood transfusions or the spleen can be removed (called splenectomy) to stop it from happening again.
Vision loss, including blindness, can occur when blood vessels in the eye become blocked with sickle cells and the retina (the thin layer of tissue inside the back of the eye) gets damaged. Some patients develop extra blood vessels in the eye from the lack of oxygen.
People with sickle cell disease should have their eyes checked every year to look for damage to the retina. If possible, this should be done by an eye doctor who specializes in diseases of the retina.
This usually occurs on the lower part of the leg. They happen more often in males than in females and usually appear from 10 through 50 years of age. A combination of factors cause ulcer formation, including trauma, infection, inflammation, and interruption of the circulation in the smallest blood vessels of the leg.
A stroke can happen if sickle cells get stuck in a blood vessel and clog blood flow to the brain. About 10% of children with SCD will have a symptomatic stroke. Stroke can cause learning problems and lifelong disabilities.
Children who are at risk for stroke can be identified using a special type of exam called, transcranial Doppler ultrasound (TCD). If the child is found to have an abnormal TCD, a doctor might recommend frequent blood transfusions to help prevent a stroke. People who have frequent blood transfusions must be watched closely because there are serious side effects. For example, too much iron can build up in the body, causing life-threatening damage to the organs.
Deep Vein Thrombosis (DVT) and Pulmonary Embolism (PE)
Sickling of red cells can increase blood coagulation and induce an increased risk of blood clot in a deep vein (DVT), or in the lung (PE) if the blood clot moves from the deep veins. People with SCD have a high chance of developing DVT or PE. DVT and PE can cause serious illness, disability and, in some cases, death.
Prevention and Treatment
Medication is used to prevent and treat DVT and PE. PE requires immediate medical attention. For more information on DVT and PE visit
Other Possible Complications
Damage to body organs (like the liver, heart, or kidneys), tissues, or bones because not enough blood is flowing to the affected area(s).
Malnutrition and growth retardation among adolescents can cause a delayed onset of puberty and, in males, infertility.
Painful erection of the penis, called priapism, can last less than 2 hours or more than 4 hours. If it lasts more than 4 hours, the person should get urgent medical help. It can lead to impotence.
A very rare form of kidney cancer (renal medullary carcinoma) has been associated with sickle cell trait.
SCD is diagnosed with a simple blood test. It most often is found at birth during routine newborn screening tests at the hospital. In addition, SCD can be diagnosed before birth.
Because children with SCD are at an increased risk of infection and other health problems, early diagnosis and treatment are important.
You can call your local sickle cell organization to find out how to get tested.
Following are the most common types of SCD:
People who have this form of SCD inherit two sickle cell genes (“S”), one from each parent. This is commonly called sickle cell anemia and is usually the most severe form of the disease.
People who have this form of SCD inherit a sickle cell gene (“S”) from one parent and from the other parent a gene for an abnormal hemoglobin called “C”. Hemoglobin is a protein that allows red blood cells to carry oxygen to all parts of the body. This is usually a milder form of SCD.
HbS beta thalassemia
People who have this form of SCD inherit one sickle cell gene (“S”) from one parent and one gene for beta thalassemia, another type of anemia, from the other parent. There are two types of beta thalassemia: “0” and “+”. Those with HbS beta 0-thalassemia usually have a severe form of SCD. People with HbS beta +-thalassemia tend to have a milder form of SCD.
There also are a few rare types of SCD:
HbSD, HbSE, and HbSO
People who have these forms of SCD inherit one sickle cell gene (“S”) and one gene from an abnormal type of hemoglobin (“D”, “E”, or “O”). Hemoglobin is a protein that allows red blood cells to carry oxygen to all parts of the body. The severity of these rarer types of SCD varies.
Sickle Cell Trait (SCT)
People who have SCT inherit one sickle cell gene (“S”) from one parent and one normal gene (“A”) from the other parent. This is called sickle cell trait (SCT). People with SCT usually do not have any of the signs of the disease and live a normal life, but they can pass the trait on to their children. Additionally, there are a few, uncommon health problems that may potentially be related to sickle cell trait.
More information coming soon.
SCD is a genetic condition that is present at birth. It is inherited when a child receives two sickle cell genes—one from each parent.
Abnormal hemoglobin, called hemoglobin S, causes sickle cell disease.
In the United States, most people who have sickle cell disease are of African ancestry or identify themselves as black.
About 1 in 13 black or African American babies is born with sickle cell trait.
About 1 in every 365 black or African American babies is born with sickle cell disease.
There are also many people who have sickle cell disease who come from Hispanic, southern European, Middle Eastern, or Asian Indian backgrounds.
About 100,000 Americans have sickle cell disease.
There is no single best treatment for all people with SCD. Treatment options are different for each person depending on the symptoms.
The only cure for SCD is bone marrow or stem cell transplant.
Bone marrow is a soft, fatty tissue inside the center of the bones where blood cells are made. A bone marrow or stem cell transplant is a procedure that takes healthy cells that form blood from one person—the donor—and puts them into someone whose bone marrow is not working properly.
Bone marrow or stem cell transplants are very risky, and can have serious side effects, including death. For the transplant to work, the bone marrow must be a close match. Usually, the best donor is a brother or sister. Bone marrow or stem cell transplants are used only in cases of severe SCD for children who have minimal organ damage from the disease.
More information coming soon.
More information coming soon.
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Sickle Cell information available to the public: https://medlineplus.gov/sicklecelldisease.html