What is sickle cell disease?

It's in your genes

Sickle cell disease is a group of inherited red blood cell disorders that can clog blood flow when red blood cells break apart. Normal red blood cells are round like donuts and move through small blood vessels to deliver oxygen. Sickled blood cells are hard, sticky, and shaped like crescent moons or sickles. When these hard, pointed red cells go through small blood vessels, their shape can compromise blood flow and cause them to fragment. This can cause pain and damage to the organs they are running through, and result in a low red blood cell count, or anemia.

What makes the red blood cell sickle?

There is a protein in the red blood cell called hemoglobin that carries oxygen inside the cell. One little change in this protein causes the hemoglobin to form long rods in the red blood cell when it is stressed, such as when there are low oxygen levels, fever, or dehydration. These rigid rods give the red blood cell a sickle shape instead of the round shape:

Graph showing the causes of sickle cell anemia.
  • Sickle cell disease is caused when the patient inherits one gene for the disease from both parents: mother and father. Sickle cell trait occurs when the individual inherits one gene from one of his or her parents (either mother or father, but not from both). Sickle cell disease and sickle cell trait are both inherited conditions and cannot be ‘caught.’ If you have sickle cell disease or sickle cell trait you will have it for all your life, unless you have treatments that change your genes, such as a bone marrow transplant.

  • There are 3 common types of sickle cell disease in the United States.

    • Hemoglobin SS or sickle cell anemia

    • Hemoglobin SC disease

    • Hemoglobin sickle beta-thalassemia

    Each of these can cause sickle pain episodes and complications, but some are more common than others and some cause more severe disease than others. All of them may also be associated with an increase in fetal hemoglobin, which can reduce how much the red blood cell sickles and, in this way, help prevent complications. The medication hydroxyurea also increases fetal hemoglobin.

  • Complications from the sickle cells blocking blood flow and early breaking apart include:

    • Low red blood cell counts, called anemia

    • Yellow eyes or jaundice

    • Pain episodes

    • Stroke

    • Increased risk of infection

    • Bone damage, including damage to hips and shoulders thinning of the bone, called avascular necrosis

    • Gallstones at a young age

    • Lung disease, called acute chest syndrome

    • Kidney disease, called nephropathy

    • Nighttime bedwetting, called enuresis

    • Painful erections in boys and men called priapism

    • Blood blockage in the spleen or liver called sequestration

    • Eye damage, called retinopathy

    • Delayed growth and development

    • Leg ulcers

    • Difficulty having children

  • A patient with sickle cell disease should be under the care of doctors and other providers who understand sickle cell disease. All newborn babies with sickle cell disease should be started on daily penicillin to help reduce the risk of serious infections. All of the childhood immunizations should be given plus other vaccines to protect against certain bacteria that can cause serious infections in those with sickle cell disease. Parents should know how to check for a fever because this signals the need for an urgent medical checkup to look for a serious infection. The following are general guidelines to keep the patient with sickle cell disease as healthy as possible:

    • Twice daily penicillin until age 5 to reduce serious infection

    • Talk to your doctor and, if appropriate, take hydroxyurea every day

    • Drinking plenty of water daily

    • Avoiding too hot or too cold temperatures

    • Avoiding overexertion and stress

    • Getting plenty of rest

    • Getting regular check-ups from knowledgeable healthcare providers

    Patients and families should watch for the following conditions that need an urgent medical evaluation:

    • Fever

    • Chest pain

    • Shortness of breath

    • Increasing tiredness

    • Abdominal swelling

    • Bad headache

    • Any sudden weakness or loss of feeling in an arm or leg or the face

    • Pain that will not go away with home treatment

    • Priapism (painful erection that will not settle)

    • Sudden vision change