What is Sickle Cell Disease?
Sickle cell disease is also called as sickle cell anaemia. The disease is an inherited disorder that changes the shape of the red blood cells.
The red blood cells carry oxygen to all parts of the body. A normal red blood cell will be flexible so that the cells can easily pass-through various types of blood vessels.
If there is a defect in the red blood cells, it can affect the potential of the cell to carry oxygen. The defective red blood cells become sticky and take the shape of a crescent moon or sickle.
These defective red blood cells tend to stick together and become less flexible, which can block the blood flow or reduce the oxygen-carrying capacity of the cell.
Currently, there is no cure for the disease, but there are many treatments available to reduce the pain and complications associated with the disease.
Types of sickle cell disease
The red blood cells contain a protein called haemoglobin. The haemoglobin helps to carry oxygen from the atmosphere to the lungs and from the lungs to other parts.
The haemoglobin contains two alpha and beta chains. If there is any mutation in the genes, it can lead to sickle cell disease. The most common types of sickle cell disease are briefed below.
HbSS (Haemoglobin SS disease)
Haemoglobin SS disease (HbSS) is the most common and severe form of anaemia. When there is a mutation in the beta-globin gene, this type of disease occurs.
The glutamic acid will be replaced by valine, which leads to the formation of the HbS chain. The HbS chain forms long polymer chains, which causes the formation of less flexible red blood cells.
The polymer formed leads to biochemical and rheological changes, and these changes impair the blood flow, which causes vaso occlusion.
The reduced blood flow can lead to ischemic injury and can cause pain in the affected people.
HbSC
After the HbSS type, HbSC is the second most common type of sickle cell disease. The mutation occurs when the baby inherits the C gene from one parent and the S gene from the other parent.
Compared to the HbSS, this type is less severe. And HbSC causes increased lipid levels. Vaso occlusion and pain were also observed in patients affected with this type of disease.
The HbSC disease causes dehydration of RBC cells which leads to the concentration of the haemoglobin cells. The cells become denser, and makes it even more difficult to flow, and blockage occurs. As a result, the patient can feel pain.
HbS beta thalassemia
Sickle cell beta thalassemia is a type of sickle cell disease that affects the production of haemoglobin. The beta-thalassemia is caused due to a mutation in the HBB gene.
This causes the red blood cells to become sickle-shaped. A defect in the cells causes low production of haemoglobin.
The severity of the disease depends on the mutation of the gene. The sickle cell beta zero thalassemia will have no normal red blood cells, and the sickle beta plus thalassemia will have a reduced normal red blood cell.
The symptoms of zero thalassemia are more severe when compared to sickle beta plus thalassemia.
Symptoms of SCD
The symptoms of sickle cell anaemia might be the same as the anaemic condition. However, there are certain symptoms that should be closely monitored.
Anaemia
Anaemia occurs when there is a deficiency in the red blood cells. A normal red blood cell has a lifespan of 120 days, but a defective red blood cell dies within 20 days.
As a result, it leads to a shortage of red blood cells, and the body will be deprived of oxygen. When the body is deprived of oxygen, there can be other symptoms like fatigue and weakness.
Episodes of pain
Episodes of extreme pain can indicate sickle cell disease. These episodes of pain are called sickle cell crisis. Episodes of pain are a common symptom of sickle cell anaemia and affect the quality of life.
The pain can be caused when a certain blood vessel gets blocked. The pain can last up to about 7 days. The commonly affected body parts are
- Stomach,
- Ribs,
- Spine,
- Breastbone,
- Legs and
- Hands or feet.
The episodes of pain can differ from one person to another. In some cases, the pain can be felt once a year, and for a few people, it can be once in a few weeks.
The reason for the episodes of pain is not very clear. However, the pain can be influenced by other causes like stress, health conditions and dehydration.
Swelling of hands and feet
Swelling of hands and feet is common in infants and babies. The swelling can signify sickle cell anaemia. The swelling can sometimes be assisted with fever.
The less flexible red blood cells block the blood flow in the blood vessels and small bones, which can lead to pain and swelling in the hands and feet. The swollen areas on the hands and feet can have a raised temperature.
Frequent infections
People affected with sickle anaemia are vulnerable to frequent infections. The infection ranges from the common cold to pneumonia, salmonella and meningitis. These infections may be life-threatening to people affected with sickle cell disease.
Sickle cell disease damages the spleen, which increases the risk of frequent infection. These infections are more frequent in young people and infants.
Vaccination can help prevent infection in babies and infants. However, people affected with sickle cell disease are more prone to infection that can be life-threatening.
Delayed growth or puberty
Sickle cell disease causes complications in children and babies. Sickle disease delays the growth and puberty of children.
The delayed growth is due to defective red blood cells. It can also be due to a fewer count of red blood cells.
Children affected with sickle cell anaemia in their later stage are shorter compared to the general population.
Children with sickle cell anaemia require more vitamins and nutrients when compared to the other children.
Vision problems
The blood supply to the eyes gets affected, which can cause vision problems. When the blood supply reduces, it can damage the retina, which can lead to vision problems.
Diagnosis of SCD
The diagnosis of sickle cell disease can be done with a blood test. It can also be diagnosed when the baby is still in the womb.
After the child is born, a complete blood count (CBC) will also help to find the deficiency in the haemoglobin level. Along with the complete blood count, Mean Corpuscular Volume (MCV) is recommended to identify any abnormality in the red blood cells.
There are other tests like haemoglobin electrophoresis, high performance liquid chromatography (HPLC) and DNA testing to find abnormal haemoglobin.
Treatments of SCD
There are many treatments available after the development in the medical industry.
Medications
There are many medications available to treat sickle cell disease.
- Hydroxyurea
- L-glutamine oral powder
- Voxelotor
- Crizanlizumab
These are some of the common medications used to treat sickle cell disease. The doctor might also prescribe some painkillers to help alleviate the symptoms of the disease.
Blood Transfusions
When these medications do not help with the symptoms and complications, blood transfusion is recommended.
Most of the time, patients are recommended with blood transfusion or hydroxyurea therapy.
When patients have acute complications, blood transfusion can help reduce the occurrence of seizures and stroke.
Stem cell transplant
Stem cell transplants can be a cure for the disease. The treatment can be considered when the affected person is below 16 years.
The stem cell transplant can give permanent relief from various complications like seizures, stroke and other pain.
However, as the child ages, there are certain complications like organ failure due to immune reactions. The transplant will be done by suppressing the natural immune response.
Currently, for adults, bone marrow transplant is being considered and under research. A bone marrow transplant can also avoid the risk of organ failure.
When to see a doctor?
Consult your doctor when you experience complications like
- Severe numbness
- One-sided paralysis
- Severe pain in feet and hands
- Severe headache and Vision problems.
Children affected with sickle cell disease may experience severe fever. Sometimes, the symptoms can be life-threatening.
Conclusion
Sickle cell disease is an inherited disorder most of the time. If your family has a history of sickle cell disease, consult your genetic counsellor before getting conceived.
The disease can be identified when the foetus is in the womb. It can be prevented with prompt diagnosis and treatment.
