Types of Sickle Cell Disease

When you think of a red blood cell, think of a round flat disk with smooth raised edges. Think of a donut or a gummy candy without a hole. It’s this very shape and size of 6-8 µm in diameter which allows it to move easily throughout the body’s intricate circulation system. If a red blood cell changes in either of these characteristics, a person will become symptomatic and if there is also a reduction in the number of total red blood cells they will become anemic

There are several types of anemia which can occur in the body. Our focus is on the various types of sickle cell disease and the clinical research which is improving the lives of those who have been diagnosed with it. It is a lifelong illness. A blood and bone marrow transplant is currently the only cure for this condition, but there are effective treatments that can reduce symptoms and prolong life.

Sickle cell anemia can be diagnosed in young children because its symptoms present early in life. You may notice a child has jaundice, fatigue, or painful swelling of the hands and feet. These signs can be present in a child as young as five months old. A definitive diagnosis can be done through blood tests and the condition is confirmed by the presence of red blood cells which are shaped like sickles or crescent moons, instead of round disks. 

These sickled cells are inflexible, rigid, and cannot move through blood vessels smoothly or easily. They burst open in transit and last only 10-20 days as compared to a normal red blood cells lifespan of 90-120 days. Their unique shape also causes them to stick to blood vessels and over time create clots, which can cause a slowing down or blockage of blood flow to organs. The blocked blood flow can lead to serious problems including stroke, eye problems, infections, and severe pain referred to as “pain crises”. 

There are four types of sickle cell disease, differentiated from each other because of varied gene expression. 

  • Hemoglobin SS disease – This is the most common and severe type of sickle cell anemia.  It occurs when you inherit a copy of the hemoglobin S gene from each parent. 


  • Hemoglobin SC disease  – This is the second most common sickle cell subtype and you will have similar symptoms to individuals with Hb SS but with less severe anemia.


  • Hemoglobin SB+ (beta) thalassemia – In this type of anemia, 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 and symptoms are not as severe. 


  • Hemoglobin SB 0 (Beta-zero) thalassemia -This is the fourth subtype of sickle cell anemia and it has similar symptoms to Hb SS anemia. However, sometimes the symptoms of beta zero thalassemia are more severe and the prognosis is poor.


Although there is no cure for sickle cell at this time other than bone marrow transplants, there is hope for a healthy life with lowered disease symptoms. Eating healthy, staying hydrated, and controlling severe temperature exposure can prevent a pain crisis. Currently used medications primarily focus on managing pain, preventing infections, reducing anemia, and prolonging red blood cell life. While bone marrow transplants are a cure for sickle cell, they are not commonly used because of complications involved with transplants themself. In addition to these, there are clinical researchers investigating the use of genetic therapies to prevent the occurrence of disease by correcting problems within the DNA. With more research and research participation, scientists hope to find a cure! The ongoing clinical trials such as this, are just one example of an opportunity for you to become an active participant in finding a future cure. 


By Nadia Bhatti

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