Sickle Cell Disease: Symptoms, Causes, Diagnosis, Consequences
You can find in this Youtube video and in this health and wellness blog post:
- What is sickle cell disease?
- What are the causes of sickle cell disease?
- What are the symptoms of sickle cell disease?
- The diagnosis of sickle cell disease
- What are the consequences of sickle cell disease?
- How does sickle cell disease manifest itself in an individual?
- Definition of recessive genetic diseases
- Definition of dominant genetic diseases
- Treatments for sickle cell disease
- Sickle cell disease and the desire to become pregnant
- How to have a child with sickle cell disease?
To begin with, it is important to know that sickle cell disease is a genetic disease that causes a deformation of red blood cells.
Red blood cells are blood cells whose role is to transport oxygen through the blood thanks to a protein they contain called hemoglobin.
Red blood cells are produced in the bone marrow (the substance found in the long and flat bones).
Normally, red blood cells are spherical in shape and have a medium size that allows them to contain a certain amount of hemoglobin.
Oxygen is taken up by the hemoglobin and transported through the blood vessels. Then, it is brought to the different cells of our body to ensure their multiple functions, such as energy production.
In sickle cell disease, there is an abnormality in the person's genetic code, which causes the production of an abnormal hemoglobin called hemoglobin S. This hemoglobin is less soluble than the hemoglobin in the blood. This is less soluble than the normal hemoglobin called hemoglobin A.
When the level of oxygen in the blood decreases, due to dehydration, fever, etc., this loss of solubility causes the red blood cells to become deformed, sickle-shaped, rigid and fragile.
It is important to know that sickle cell red blood cells have a shorter life span than normal, 21 days instead of 120 days. The bone marrow is not able to compensate for this lack, the number of red blood cells is always decreasing, which results in long-term anemia.
Sickle cell disease mainly affects people of African (all of Africa) and West Indian origin, but also people from the Middle East, India, Greece and Sicily.
It is interesting to know that this genetic disease is recessive.
Just a reminder, our body is made up of organs, these organs are formed by tissues that are composed of many cells.
The cells contain a nucleus that contains our entire genetic code called DNA (deoxyribonucleic acid). This genetic code is written within structures called chromosomes.
Each cell in our body has 23 pairs of chromosomes, for a total of 46 chromosomes. Depending on the type of cell in which they are found, the genetic code within the chromosomes will allow the production of different elements (proteins, hormones, ...).
In some cases, this code can be abnormal, which causes the appearance of a genetic disease.
There are 2 main groups of genetic diseases:
- Recessive genetic diseases, in this case, it is necessary that the genetic anomaly is present on both chromosomes of the pair, so that the disease appears
- Dominant genetic diseases, the disease is expressed when the mutation is present on only 1 chromosome of the pair
The mutation that causes sickle cell disease is found on chromosome number 11.
Sickle cell disease being a recessive genetic disease, there are several possibilities, either the mutation is found on only 1 chromosome, in which case the person is said to be a healthy carrier, he/she has no symptoms, the disease is not expressed, but he/she can transmit the mutated gene to his/her descendants, or the mutation is found on both chromosomes and in this case the disease is expressed, the patient will transmit the mutated gene to his/her descendants.
What is surprising in sickle cell disease is that the mutation has on the one hand caused the disease, but it has also given people who carry the mutation a greater resistance to another disease which is malaria, which has benefited these populations over the long term and has favored the transmission of this gene from generation to generation.
The symptoms of sickle cell disease are anemia which leads to severe fatigue, repeated infections and severe pain in various organs.
Sickle red blood cells can interfere with the proper flow of blood through the arteries, which hinders the proper oxygenation of cells. This is called a vaso-oclusive crisis (blockage of good blood flow by the deformed and rigid red blood cells, which causes pain). This happens when the person lacks oxygen because of dehydration, cold or intense heat, great physical effort, stress, fever, ...
The symptoms of sickle cell disease vary greatly from person to person depending on the compensation, the adaptation of the body and the severity of the disease. The most common symptoms are anemia, fatigue, shortness of breath, increased heartbeat, yellow eyes and skin.
The diagnosis of sickle cell disease is usually made at birth, based on the origin of the child and the symptoms he or she may have. It is a chronic disease, it accompanies the patient throughout his life.
It is imperative that the patient is regularly monitored by his specialist (hematologist) and other specialists (multidisciplinary monitoring) concerned by the complications that may arise from this disease (ophthalmologist, cardiologist, etc.).
The treatment of sickle cell disease allows to limit anemia, to reduce infections and to relieve pain. The treatments must be associated with a healthy lifestyle in order to limit complications and to allow the person to have a certain quality of life.
Transfusions may be initiated, bone marrow transplants and gene therapy may be suggested to the patient in severe cases.
Bone marrow transplantation consists of replacing the patient's hematopoietic stem cells (cells responsible for the production of blood cells such as red blood cells) in the patient's bone marrow with cells of the same type, but healthy (without the mutation) from a donor who may be a family member who does not carry the mutation. The transplanted cells then produce red blood cells that contain normal hemoglobin. This operation is quite complex and is only performed in severe cases where the disease is not controlled.
For more information on gene therapy click here (explanations at the end of the video on anemia)
To avoid transmission of the disease to the child, it is recommended that people who suffer from this disease or who are healthy carriers of the mutated gene check whether their partner is also a carrier of this mutation before trying to conceive a child.
If the risk is high, a prenatal diagnosis can be performed between 12 and 16 weeks of pregnancy. This allows to see if the fetus has the genetic anomaly or not, if it has the anomaly on these 2 chromosomes, it means that it will be born with sickle cell disease, in this case, it can be suggested to the parents to interrupt the pregnancy, if they wish.
A pre-implantation diagnosis can also be carried out, this involves forming the embryo in in vitro fertilization, then choosing the one that will not carry the anomaly on its 2 chromosomes and implanting it in the mother's uterus.
Dr Noura Marrai (Doctor of Pharmacy, YouTuber Health, creator of the health well-being Pharmaquiz application),
Pharmaquiz YouTube channel:https://www.youtube.com/channel/UC3CzlCm-0Yh7-lYM6K2SfVg?sub_confirmation=1
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