We all know that we don’t talk about Sickle Cell Disease (SCD) enough but when we do talk about sickle cell, we normally talk about Sickle Cell Trait (when you are a carrier) or Sickle Cell Anaemia (the full-blown disease). What if I told you that there are different forms of sickle cell? Would you be able to name them? Could you even tell me a bit about that different type of sickle cell that is not your own or your loved ones?
Don’t fret if the answer to those questions is a no and another no! Even as a Sickle Cell sufferer myself, I have only recently heard/learnt about the different forms and strains of the disease, but that’s because I am invested in knowing all it is to know about this disease! So, I thought I would take a few moments to draw attention to the different types of sickle cell that people can and do suffer from, just so that we are all aware and saying the right things when we do finally start talking about the different forms of SCD.
Before I begin, here comes the science behind why there are different types of SCD: “Sickle Cell Disease” is an umbrella term used to describe a group of inherited disorders that affects the haemoglobin in the body. Haemoglobin is the protein in red blood cells that carries oxygen around the body. It is made up of 2 alpha globin chains and 2 beta globin chains. SCD is caused by a mutation in the beta globin gene, resulting in abnormal haemoglobin, called sickle haemoglobin or Hb S. Different types of SCD arise depends on whether the haemoglobin beta S gene inherits another beta S gene or another beta gene mutation.
Haemoglobin SS Disease
Haemoglobin SS Disease is the most common and most severe type of SCD. It occurs when you inherit the haemoglobin S gene mutation from both parents. In this type, the body only produces haemoglobin S. This form of the disease is often called “Sickle Cell Anaemia.” (This is the type of SCD that I have always known to have but there are debates from certain doctors about whether I may have the type of SCD listed immediately below).
Haemoglobin SB 0 (Beta Zero) Thalassemia
Haemoglobin S beta zero thalassemia occurs when you inherit the haemoglobin S gene from one parent and you inherit a haemoglobin S beta zero thalassemia gene mutation from the other parent. Haemoglobin S beta zero thalassemia has similar symptoms to the haemoglobin SS disease and is, therefore, also called sickle cell anaemia, because the body only produces haemoglobin S.
Haemoglobin SC Disease
Haemoglobin SC Disease is the second most common form of SCD. It occurs when you inherit the haemoglobin beta S gene from one parent and the abnormal haemoglobin called “C” from the other parent. People with the haemoglobin SC Disease may have similar symptoms to the haemoglobin SS disease, but their symptoms may be less severe.
Haemoglobin SB+ (Beta) Thalassemia
Haemoglobin S beta plus thalassemia occurs when you inherit the haemoglobin beta S gene from one parent and the haemoglobin beta plus thalassemia gene from the other parent. In this form of SCD, normal haemoglobin is produced but in reduced amounts. Because normal haemoglobin is produced, this form is less severe than haemoglobin SS disease. Symptoms are usually milder than haemoglobin SS or SC disease, but complications can still develop.
Haemoglobin SD, Haemoglobin SE, and Haemoglobin SO
Haemoglobin SD, haemoglobin SE and haemoglobin SO are rarer types of SCD. People who have these forms of SCD inherit the haemoglobin beta S gene and the abnormal type of haemoglobin called “D, E and O.” The severity of these rarer forms of SCD varies.
Sickle Cell Trait
People who inherit sickle cell trait, inherit one haemoglobin beta S gene from one parent and a normal gene called “A” from the other gene. This combined forms Sickle Cell Trait, also known as “AS.” People with sickle cell trait usually do not show any signs of the disease and live a normal life, but can pass the trait on to their children. Additionally, there are a few uncommon health problems that may potentially be related to sickle cell trait.