Sickle Cell Disease Oversimplified I: The Basics
Growing up, in primary school, my closest male friend was Kweku. Kweku was the sweetest. There was not a single morning Kweku came to class without bringing me sweets (Yes! You can blame Kweku for my sweet tooth). The only problem was, Kweku was hardly in school. He constantly missed more than half of the academic year and though a child of brilliance and wit, Kweku ranked dead last in class.
Later, I found out from a friend Kweku was a ‘Sickler’. I found that to be a curious term. In my little mind’s eye, it meant someone who was always sick. That was not far from the truth though. Kweku was constantly being admitted into the hospital; he was never out of the hospital for longer than two weeks or at least that is how it felt.
For the few days he was back in school, though he looked longingly at them, he never joined the boys for football (Not that I’m complaining. It meant more Kweku time for me). He never got to play in the rain. He felt like a prisoner in his own body. His mind wanted to do things that his body couldn’t physically do – even the simple everyday things. This, sadly, is the plight of many of the millions of people living with sickle cell disease in the world.
What is sickle cell disease (SCD)?
SCD is an inherited lifelong disease caused by an abnormality affecting the red blood cells – specifically the haemoglobin. The blood contains three main cell types namely the red blood cells, white blood cells and platelets. The red blood cells are disc-shaped with an indented centre (Kind of like a doughnut without a hole).
The red blood cells carry fresh oxygen around the body. They do this with the help of haemoglobin. Haemoglobin is an iron-rich protein inside red blood cells
which carries oxygen. In sickle cell disease, due to an abnormality in the haemoglobin protein which I would try to explain later, the red blood cells assume the shape of a sickle (for the game of thrones fans, the sickle looks like the Dothraki weapon – the Arakh).
This impairs the ability of the Red Blood Cells to travel through the blood vessels. Also, unlike the normal red blood cells which last 90-120 days, the sickled ones last for only about 10-20 days.
How is Sickle cell disease/trait inherited?
The sickle cell gene is passed from generation to generation in a pattern of inheritance called autosomal recessive inheritance. This means a child must inherit the mutated gene (defective form) from both the mother and the father to be affected.
If the child inherits the sickle cell gene from only one parent, the child will have sickle cell trait, with one normal haemoglobin gene and one defective haemoglobin. Individuals with the sickle cell trait make both normal haemoglobin and sickle cell haemoglobin. Their blood might contain some sickle cells, but they generally don’t show any symptoms. Nevertheless, they are carriers of the disease, which means they can pass the gene to their children.
Understanding the jargons
Before delving into why what we have described is a problem, let’s try to understand some of the jargons that are thrown about whenever Sickle cell is being discussed. As mentioned earlier, haemoglobin is a protein and just like all proteins, it is made up of a chain of amino acids. Whenever there is a change in one of the amino acids, there is a resulting abnormal haemoglobin. The normal haemoglobin (Hb) is called HbA. Abnormal variants of Hb include HbS, HbC and Hbβ-thalassemia among others.
When a person has both HbA and HbS, it is known as sickle cell trait (AS). Sickle cell disease is when an individual has two abnormal Haemoglobins with one of those being, HbS. So, Sickle Cell Disease (SCD) includes those who are SS, SC, SB thalassaemia etc.
People with HbSS are specifically said to have Sickle Cell Anaemia (SCA); which is the worst manifestation of the disease.
Symptoms of sickle cell disease
People with SCA, manifest a myriad of symptoms; starting as early as childhood. By the 2nd year of life, children may experience pain in the limbs. This pain is associated with swelling of the hands or feet, either on both sides or on just one side. This is known as hand-foot syndrome or dactylitis. So basically, the fingers and toes look like sausages and the child is in pain. This is usually the first manifestation of the disease in people with SCA.
The main symptoms are
- painful episodes
- getting infections often
Episodes of pain
Periodic episodes of pain, called crises, are a major symptom of sickle cell anaemia. This pain can be of varying intensity and duration and develops when sickle-shaped red blood cells block blood flow through tiny blood vessels to your chest, abdomen and joints and also bones. Our next post will go into detail on the various types of crisis and how to manage them.
Red blood cells usually live for about 120 days before they need to be replaced. But sickle cells usually die in 10 to 20 days, leaving a shortage of red blood cells (anaemia). Sickle cells break apart easily and die, leaving you without enough red blood cells. Without enough red blood cells, your body can’t get the oxygen it needs to feel energized, causing easy tiredness.
The spleen is one of the organs that fight infection. Sickle cells can damage the spleen, leaving you more susceptible to infections. Infants and children with sickle cell anaemia are given vaccinations and antibiotics to prevent potentially life-threatening infections, such as pneumonia.
Complications of sickle cell disease
SCD is associated with innumerable complications. It affects all the body systems; whether directly or indirectly. Some of these complications include:
- Organ damage
- Delayed growth during childhood and delayed puberty
- Eyesight problems, such as floaters, blurred or patchy vision, reduced night vision and occasionally sudden vision loss
- Painful open sores on the lower legs Leg ulcer
- A persistent and painful erection of the penis (priapism), which can sometimes last several hours
Prevention of sickle cell disease
Know your sickling status and seek genetic counselling if you have a sickle cell trait before trying to conceive. To know your status, walk into any medical laboratory and request to know your sickling status. They will perform a blood test for you known as Hb Electrophoresis. The results of this test will let you know your genotype (AA, AS, AC, SS, SC, etc.).
Before you play the game of chances, the least you can do is to understand the risk and consequences.