Types of Sickle Cell Disease

What are the different types of sickle cell? And for people like me that don't always have crises except on rare occasions, what category are we classified in?


There are many types of sickle cell disease and many factors the influence how severe this disease is.


There are hundreds of types of hemoglobin, some are just curiosities; they transport oxygen normally, with some small change in the structure. There are other abnormal structural hemoglobin types that can cause disease, such as hemoglobin S.  Some people are born with no normal beta hemoglobin genes (beta thalassemia major).  The common types of hemoglobin are: A (normal), S, C, E, thalassemia (many different types).  Uncommon hemoglobin types causing disease with S are: OArab, DLos Angeles, CHORI.


With the exception of sickle cell trait (AS), some people would call any hemoglobin combined with S to be “sickle cell disease”, even if there were no “disease” associated with the combination.


You could have hemoglobin S with a rare hemoglobin type that does not cause severe disease, like SE which is a combination that is usually without problems; especially in children.


It is more complicated than this.  Other genetic factors influence how severe your sickle cell disease is.  Hemoglobin is made of two proteins beta hemoglobin (where the mutations for sickle cell diseases are) and alpha hemoglobin (mutations cause other types of hemoglobin disorders).  If you are missing an alpha gene (the most common gene mutation worldwide) and have SS (sickle cell anemia) your hemoglobin is higher and you are protected against some complications of sickle cell disease.  If you have a mutation that causes an increase in fetal hemoglobin (the hemoglobin babies have before they are born) this will protect you against many complications of sickle cell disease.  The more fetal hemoglobin you have the fewer complications you are likely to have.


Hemoglobin S beta thalassemia is another group of sickle cell diseases that are sometimes lumped together, but are not the same.  As I noted above there are hundreds of hemoglobin mutations some causing different types of thalassemia.  The range of thalassemia mutations is from having no hemoglobin A (S beta zero thalassemia: S b0 thalassemia), to having some hemoglobin A (S beta plus thalassemia: S b+ thalassemia).  S b0 thalassemia is pretty straightforward: you have S with no A, so that is the same as SS in severity.  S b+ thalassemia is a different story.  There are 14 different moderate to mild thalassemia mutations that are found in African Americans out of the hundreds that are seen worldwide.  Some of these  b+ thalassemia mutations are minor and a higher amount of hemoglobin A is made (closer to sickle cell trait, but never nearly as much A) and some are severe with almost no hemoglobin A made (closer to S beta zero thalassemia).  It has not been reported, but the amount of hemoglobin A could determine the severity of your symptoms.


For people who love hemoglobin, and like details, it can get even more complex.


If you want to know why you have “sickle cell disease” and have few symptoms see your healthcare provider (or a hematologist specializing in sickle cell disease) and ask that you have: hemoglobin electrophoresis, alpha gene mapping, and testing for your beta gene mutation if it turns out you have S b+ thalassemia.


Bottom line: Take care of yourself if you have sickle cell disease of any kind.  You need to act like it is serious and do all of the things other people with sickle cell disease are supposed to do.  See your healthcare provider on a regular basis and have a hematologist who knows about sickle cell disease as one of your healthcare providers.  Remember, there have been deaths in people with sickle cell trait during heavy exercise and splenic sequestration at high altitudes.  AND: know your diagnosis.



My daughter has sickle beta-thalassemia and I get told that it is a more mild version of sickle cell. However, she has seemed to have had so many complications in her life. She has had acute chest syndrome multiple times, her gallbladder has been removed, she has some infarction in her lungs due to the pneumonia and acute chest syndrome, she has an enlarged heart, and she has had multiple pain crises. She's only eight years old and has been admitted to Children's Hospital on the average of 4 to 5 times a year. In 2015 we were in the hospital every month except for two months of the entire year.


My question to you is, do you believe that this is a more mild version of sickle cell? And if my daughter has a bone marrow match with her sibling should we pursue that even though we're being told that with the more mild version she doesn't need to have this done?


Is there “mild” sickle cell disease?  Technically: yes.  Really: no.  Sickle cell disease is unpredictable.


Obviously, Jordin does not have “mild” sickle cell disease no matter what her hemoglobin combination.  There are children who have a “mild” form of sickle cell disease who have severe problems as you are describing, including splenic sequestration, avascular necrosis of the hips, and bacteremia.  An explanation of hemoglobin S diagnosis and severity is given as a response to another question.


Whether or not Jordin should have a progenitor cell transplant is something you need to discuss with a transplant physician and a pediatric hematologist who cares about and for children with sickle cell disease.  You may want to have a second opinion with someone who is a known expert in the field.  There are several doctors in North America who fit this description.  The risk transplant has to be weighed against the severity of disease.  There are serious side effects of transplantation that need to be considered should you decide to have the therapy. Discuss outcomes with a transplant physician who has experience with transplantation in sickle cell disease.  Know how many transplants have been done and what the outcomes have been for the transplant physician and hospital you choose.  Have confidence you are making the correct decision with the best physician.  There is a discussion of transplant in the answer to another question.


While you are waiting for all of this to transpire ensure Jordin is receiving the best possible treatment to decrease the severity of her sickle beta thalassemia.  If the diagnosis is S beta plus thalassemia, (I assume that is the diagnosis, it should be confirmed if there is any doubt) she could still benefit from hydroxyurea.  Hydroxyurea has been given to children as young as two years old, it has been used in adults who have sickle cell disease since the 1980’s successfully decreasing symptoms and improving organ function.  It is generally underutilized.  It does have side effects and needs to be monitored by a hematologist.  One of the possible side effects is cancer.  An increase in cancer has not been seen in people with sickle cell disease over the decades it has been used.  This remotely possible risk has to be weighed against the real risk of having severe complications of sickle cell disease.  Probably 5% of people given hydroxyurea do not have a good response or have side effects that make this medication ineffective.


Jordin should have pulmonary function testing.  If she has evidence of airway hyper-reactivity/asthma, see a pulmonologist familiar with sickle cell disease who can guide treatment.  There are some other things to do, which you probably already are doing, with hydration, diet, vitamins and general care.


Continue to give your daughter all the love and attention she is obviously receiving, but don’t smother her.  Remember she is a kid who wants to do kid stuff, even with severe sickle cell disease kids can still be kids.



Disclaimer   |   Sitemap   |   Copyright © 2017 Sickle Cell 101. All rights reserved.


Social Media Education

Events & Outreach

Contact Us


Quick Facts

Sickle Cell Disease

How It's Inherited


Sickle Cell Trait


Health Management




Ask Dr. Q

Expert Opinion Pieces



Become a Member

Donate Today

Our Sponsors