What happens in sickle cell anemia, exactly?

My exams are over, and after some dreadful months I am finally a free woman!! This means that it’s time to get back to the old writing routine. You have no idea how happy I am about that. 

 

What is it? 

Sickle cell anemia (SCA) is a hereditary blood disorder that reduces the blood’s ability to carry oxygen. Hemoglobin is a protein found in our red blood cells that binds to oxygen and that way helps to transport it from our lungs to all parts of our body. The change of one coding unit in the DNA causes the hemoglobin to sometimes collapse on itself, so that the cells become sickle-shaped, badly functioning, and short-lived.

Typical symptoms of SCA include anemia, episodes of pain when the faulty cells block blood vessels,  swelling in hands and feet, lots of infections, delayed growth, and problems with sight.

SCA is what happens if you get the same altered gene from both your mother and your father. If you only get one copy, you have something called a sickle cell trait. This condition rarely causes symptoms because you also have the normal form of hemoglobin in your blood, and it can actually protect you against malaria. About 3.2 million people in the world have SCA, while about 43 million have sickle cell trait. Most cases occur in the southern parts of Africa.

What causes it?

The gene mutation that causes SCA is a tiny flaw of one coding unit. Proteins like hemoglobin are made from amino acids using the instructions in genes. This particular mutation causes one amino acid to change into another, and this makes the protein less stable. When there isn’t enough oxygen around, it can collapse on itself. Even if the protein does succeed in returning to it’s original form, the cell membrane of the red blood cell has been damaged and it will likely die quite soon.

The gene is recessive, which means that it doesn’t cause the disease unless it is inherited from both parents. A person who has one healthy and one mutated gene will produce both the correct and the faulty hemoglobin, but having some correct proteins protects them from the more serious complications of SCA.

What happens during it?

The actual anemia that is typical to the disease happens when the collapsed proteins break the membranes of red blood cells and cause them to fall apart. The bone marrow tries to compensate through producing more cells, but it can’t keep up to the pace – normal red blood cells live 120 days on average, while the cells of someone with SCA can live only about 20 days on average. Sometimes this process can accelerate to the point of becoming a crisis, and sometimes in these situations blood transfusions can be necessary.

There are many life-threatening complications that people with SCA are at a high risk of experiencing. One of them is called the vaso-occlusive crisis. It happens when the faulty cells clump up and block a blood vessel. Cells can’t function for very long without a constant supply of oxygen, which is why this can be dangerous – this is especially the case, if the clump is in a vessel leading to a vital organ like the lungs.

How can it be treated?

Avoiding the episodes of pain called sickle cell crises is an important thing to do. They can be prevented through keeping hydrated and avoiding sudden temperament changes through, for example, wearing appropriate clothing and not swimming in cold water. Several medications can be used to treat the condition, to protect the individuals from infection because their immune systems aren’t functioning as they should, and managing pain. Bone marrow transfusions have been effective in children, and the recent advances in gene technology give a good reason to hope that SCA might some day be cured through eradicating the genetic cause itself.

 

 

Sources: https://en.wikipedia.org/wiki/Sickle-cell_disease, https://en.wikipedia.org/wiki/Hemolysis, https://en.wikipedia.org/wiki/Sickle_cell_trait, http://www.mayoclinic.org/diseases-conditions/sickle-cell-anemia/basics/symptoms/con-20019348, http://emedicine.medscape.com/article/205926-overview#a4, http://www.nhs.uk/Conditions/Sickle-cell-anaemia/Pages/Treatment.aspx

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