Sickle cell anemia (HbSS) is a genetic blood disorder that is the most common, severe type of sickle cell disease, in which the red blood cells, instead of being flexible and round, are rigid, sticky, and shaped like sickles or crescent moons (C-shaped). This rigidity and stickiness of red blood cells makes the hemoglobin in the cells carry less oxygen and get stuck in small blood vessels, while slowing or blocking blood and oxygen to the body tissues. Sickle cells additionally die early, causing a chronic shortage of red blood cells. When sickle cells get stuck in small blood vessels, they can cause pain, infection, acute chest syndrome, and stroke. In the United States, sickle cell anemia occurs most frequently in African Americans and Hispanic Americans.

There are several alternative names for sickle cell anemia, including HbSS, sickle cell disease (SCD), sickle cell disorder, and sickling disorder due to hemoglobin S.

Sickle cell anemia is an inherited (genetic) disorder present at birth when the infant has received two sickle cell hemoglobin S genes (hemoglobin SS; HbSS), one from each parent. Sickle cell anemia is caused by a genetic mutation in the gene (HBB) that controls the production of hemoglobin, which is the iron compound that makes red blood cells that carry oxygen from the lungs to the rest of the body, causing the cells to become misshapen, rigid, and sticky. If a child only inherits one sickle cell gene, then they will be a carrier of the sickle cell trait, meaning they can pass the disease on to their children, with the body making both normal and sickle cell hemoglobin, however, generally without any symptoms of the disease.

Signs and symptoms of sickle cell anemia appear around 5-to-6 months of age and can vary and change over time in different individuals. Symptoms of sickle cell anemia include fatigue, dizziness, irritability, reduced oxygen, rapid heartbeat (tachycardia), shortness of breath (dyspnea), yellowing of the skin and whites of eyes (jaundice), a shortage of red blood cells (anemia), swelling of the hands and feet (Hand Foot Syndrome), delayed growth or puberty, vision problems, frequent infections, episodic pain (pain crises) in the chest, abdomen, joints, and bones lasting from a few hours to weeks, or chronic pain, and pulmonary hypertension (high blood pressure in major artery of the lungs).

While sickle cell anemia is a lifelong illness and there is no cure for most people with the disease, treatment can help to relieve pain, prevent complications, and prolong life. Treatment for sickle cell anemia is focused on avoiding and relieving pain and symptoms as well as preventing complications and includes medications, blood transfusions, and, for a small number of select patients, blood and bone marrow transplant (stem cell transplant), which is currently the only cure for sickle cell anemia. For patients with sickle cell anemia who have had a severe episode of splenic sequestration (trapped sickle cells in the spleen), removal of the spleen (splenectomy) may be necessary. Medications – Medications used to treat sickle cell anemia include hydroxyurea (Droxia, Hydrea, and Siklos) and l-glutamine oral powder (Endari), cirzanlizumab (Adakyeo), all of which help to decrease the number of pain crises; Voxelotor (Oxybryta), which helps improve anemia; and pain-relieving medications, such as ibuprofen and aspirin or opioids for severe pain. Children with sickle cell anemia between the ages of 2 months-to-5-years-old may be given penicillin to prevent infections, such as pneumonia, while some adults with sickle cell anemia may need lifelong penicillin, especially if they have had pneumonia or their spleen removed (splenectomy). Children with sickle cell anemia are especially at risk for childhood illness; therefore, vaccinations for pneumonia, meningitis, and an annual flu shot are necessary. Blood transfusions – Red blood cell transfusions are administered to patients with sickle cell anemia in order to increase the number of normal red blood cells and reduce symptoms and complications. Patients with sickle cell anemia who have frequent blood transfusions may be given iron chelation therapy to reduce excess iron levels (hemosiderosis) that can damage the liver, heart, pancreas, and other organs. Bone marrow transplantation (Stem cell transplantation) – In selected patients, usually children with sickle cell anemia who have significant symptoms and complications, bone marrow transplantation, also know as stem cell transplantation, may be performed using healthy bone marrow from a matched donor, such as a sibling, after which immunosuppressant drugs must be taken for life.

There are several online, local, national, and international support groups for sickle cell anemia, including the following: American Sickle Cell Association - http://www.ascaa.org/support-groups.php Sickle Cell Disease Foundation - http://www.scdfc.org/supportnetwork-groups.html Sickle Cell Society - https://www.sicklecellsociety.org/supportgroups/

Sickle cell anemia is a lifelong disease that is progressive and can lead to several complications; however, early and regular treatment can help to prevent complications and provide an improved quality of life.

Sickle cell anemia has several possible complications, including the development of leg ulcers, anemia, acute pain crisis (vaso-occlusive crisis), aplastic crisis (infection that stops production of red blood cells), chronic pain, acute chest syndrome (lung infection), organ damage, delayed growth and puberty, gallstones, pulmonary hypertension (high blood pressure in the main artery of the lungs), joint complications, kidney problems, liver complications (sickle cell intrahepatic cholestasis), splenic sequestration crisis (sickle cells trapped in spleen), priapism (painful, long-lasting erections in men), impotence, stroke, complications of pregnancy, heart problems, vision problems, and blindness.

In the United States, newborns are routinely screened for sickle cell anemia; however, if your infant or child develops any of the following symptoms, such as fever, infection, unexplained episodes of severe pain in the abdomen, chest, joints, or bone; swelling in the hands or feet; abdominal swelling and tenderness; pale skin or nail beds; or yellowing of the skin or whites of the eyes (jaundice), call the doctor immediately. If your child displays any signs or symptoms of stroke, such as one-sided paralysis in the arms or legs or facial weakness, confusion, trouble talking or walking, sudden vision changes, or unexplained numbness, call emergency services immediately.

Sickle cell anemia can only be prevented by speaking with a genetic counselor before attempting to conceive if you carry the sickle cell trait. Early diagnosis and regular treatment can help to prevent the complications of sickle cell anemia and provide a better quality of life. Individuals with sickle cell anemia can help prevent and reduce the number of pain crises by drinking plenty of water, avoiding hot and cold temperatures, avoiding high altitudes, such as flying, mountain climbing, or cities set in high altitude areas, and avoiding exposure to low oxygen levels, such as mountain climbing, extreme exercise, and military boot camp.