Sickle Cell Disease

Sickle Cell Disease is a group of disorders that are inherited and affect red blood cells.  It is inherited by both parents passing a Sickle Cell gene to the child.  Normally, red blood cells are round, smooth, and can bend.  Because of these qualities and the presence of Hemoglobin, red blood cells are able to carry Oxygen within blood and travel well in blood vessels.  The Sickle Cell gene causes the red blood cell to change shape to look like a sickle (GBT, 2020).  The change in shape of the red blood cell causes it to not be able to bend.  This lack of flexibility causes the red blood cells to block blood vessels and therefore, they get "stuck" in blood vessels and obstruct them (CDC, 2020).  Their decreased ability to travel in blood vessels affects their ability to deliver Oxygen to the body.  The change in shape also affects the length of time they are viable.  Typically, red blood cells remain in the body for up to 120 days.  Sickled red blood cells only remain in the body for 10 - 20 days (JHM, 2021).  The shorter life of sickled red blood cells causes an individual to suffer from chromic anemia.  Additionally, as they are filtered through the spleen, which filters the blood and is important in the immune system, they get stuck and damage the spleen. The damage to the spleen causes someone to be at an increased risk for infections (JHM, 2021).

There are several types of Sickle Cell Disease.  The most common is Sickle Cell Anemia (HbSS).  With HBSS, an individual has inherited two sickle cell genes (S), one from each parent.  This is the most severe form of Sickle Cell disease as symptoms occur more often and are more severe.  Other types of Sickle Cell Disease include:

• HbSC disease:  individual inherits a sickle cell gene (S) and an abnormal Hemoglobin gene (C).  This form is milder than HbSS.
• HbSBeta Thalassemia: individual inherits a sickle cell gene (S) and a Beta Thalassemia gene.  Because there are two types of Beta Thalassemia, + and 0.  HbSB+ is a mild form of Sickle Cell Disease.  HbSB0 is a severe form similar to HbSS.
• HbAS: also known as Sickle Cell Trait.  Individual inherits one Sickle Cell gene (S) and 1 normal gene (A).  There are usually no symptoms of disease. (CDC, 2020)(Healthline. 2017)

Symptoms typically begin within the first year of life.  Symptoms and complications of Sickle Cell Disease include:

• Fatigue
• Fussiness in babies
• Bedwetting - due to kidney problems
• Jaundice
• Hand - Foot syndrome - swelling and pain in hands and feet.  Accompanied by fever.
• Frequent infections - there is increased risk, especially of bacterial infections due to splenic damage.  A leading cause of death in infants and children is Pneumonia.
• Acute Chest Syndrome - chest pain, coughing, difficulty breathing, and fever.  Can be life-threatening.
• Anemia - due to red blood vessels dying after 10 to 20 days.
• Delayed growth or puberty
• Vision issues - sickle cells block blood vessels in eye damaging retina.
• Pain Crisis - sickled red blood cells get stuck and block blood vessels causing sudden mild to severe pain.
• Splenic Sequestration - occurs when many sickle cells get stuck within the spleen causing it to enlarge.  This enlargement causes sudden weakness, pale lips, fast breathing, extreme thirst, abdominal pain and fast heartbeat.
• Leg ulcers - several factors cause ulcers, usually in lower leg.  They occur more commonly in men and between 10 to 50 years old.
• Stroke - occurs when sickle cells block blood vessel to brain.
• Deep Vein Thrombosis (DVT) & Pulmonary Embolism (PE): sickled cells contribute to blood coagulation and increase risk of blood clots either in deep veins or lungs.
• Gallstones: the increased rate at which sickled red blood cells die cause increased byproducts that form gallstones.
• Pregnancy problems: increased risk of Hypertension and blood clots during pregnancy. (CDC, 2021)(Healthline, 2017)

Approximately 90% of those diagnosed with Sickle Cell Disease in the United States are of African descent with about 1 in every 365 individuals of African descent being affected and 1 in 13 having Sickle Cell Trait (NIH, 2020).  In order to be diagnosed with Sickle Cell Disease, a blood test must be done which is typically done as one of the screening tests done with newborns (CDC, 2021).  Blood tests can also determine type of Sickle Cell Disease.

There are several treatments for Sickle Cell Disease including:

• Medications:
• Voxelotor - prevents sickle shape.
• Crizanlizumab - tmca - used to treat pain crises.
• Penicillin - decreases risk of severe infections particularly by pneumococcus bacteria.
• Hydroxyurea - decreases complications and should not be used during pregnancy.
• L - glutamine oral powder -  decrease pain crises.
• Hydration - help to keep cells from deforming.
• Regular exercise and reducing stress - reduce pain crises
• Transfusions - help to treat and prevent complications.
• Blood and Bone Marrow Transplant: the only cure for Sickle Cell Disease.  Risky in adults.  Individual must have a matched donor. (Mayo, 2020)(Healthline, 2017)

To learn more about Sickle Cell Disease, watch our Youtube video:

For more information on Sickle Cell Disease, view the CDC factsheet at https://www.cdc.gov/ncbddd/sicklecell/documents/SCD-factsheet_What-is-SCD.pdf

CDC. (2021) What is Sickle Cell Disease?.  Center for Disease Control and Prevention.  Retrieved from https://www.cdc.gov/ncbddd/sicklecell/facts.html

GBT. (2020) Sickle Cell Disease.  Global Blood Therapeutics.  Retrieved from https://www.gbt.com/research/sickle-cell-disease/

  

Healthline. (2017) Sickle Cell Anemia.  Healthline.  Retrieved from https://www.healthline.com/health/sickle-cell-anemia#risk-factors

JHM. (2021) Sickle Cell Disease.  John Hopkins Disease.  Retrieved from https://www.hopkinsmedicine.org/health/conditions-and-diseases/sickle-cell-disease

Mayo Clinic. (2020) Sickle Cell Anemia.  Mayo Clinic.  Retrieved from https://www.mayoclinic.org/diseases-conditions/sickle-cell-anemia/diagnosis-treatment/drc-20355882

NIH. (2020) Sickle Cell Disease.  National Heart, Lung, and Blood Institute.  Retrieved from https://www.nhlbi.nih.gov/health-topics/sickle-cell-disease