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Sickle Cell Anemia and Gene Therapy: How It Works

Sickle cell anemia is a form of sickle cell disease (SCD) which refers to a genetic condition that affects the red blood cells (RBCs) of the patient. It’s most common among people of African, Hispanic and South Asian descent and less common among white people.

Healthy RBCs are shaped like a donut. They’re flexible and are able to move easily through the tiniest blood vessels.

But, if you have sickle cell anemia or other types or form of SCD, the affected hemoglobin in your blood will cause your RBCs to become rigid and turn to the shape of letter “C”, crescent-shaped or a sickle.

Sickle-shaped RBCs are bound to always get stuck in small vessels, rendering it difficult for blood to circulate to many body parts. Such a condition can cause pain, infections, and even tissue damage.

Until recently, only bone marrow transplants were able to cure people with SCD. But finding a donor that matches can be extremely difficult besides the significant risks  linked with the treatment.

Considering this factors, current treatment options are usually impossible or not recommended for people living with SCD.

However, gene therapy is a new cure for SCD in progress. What is it, and how does it work as a treatment? Keep reading to find out:

What is gene therapy?

Every cell in your body contains DNA, a molecular code which makes up genes. It is like a set of instructions on building and supporting every individual cell in your body.

The instructions can at times have typos, or mutations. Mostly, mutations are not of major consequence, but there are times they can hit key parts of your genes. That can harm the ability of your cells to perform their assigned task properly. This is what occurs in SCD.

Gene therapy utilizes specialized molecular tools known as CRISPR-Cas9, to fix faulty genes and restore your cells into their normal function.

How can gene therapy cure sickle cell anemia?

Gene therapy can tackle SCD in a couple of ways and both of these mechanisms are aimed at your hemoglobin genes. Hemoglobin assists your RBCs to bring oxygen from your lungs to other parts of your body.

Gene editing

This technique involves scientists using CRISPR-Cas9 to cut your DNA at the mutation sites and replacing them with the “correct” code. This approach is referred to as gene editing because in similarity, it appears like the work of a book editor.

When utilized in SCD, CRISPR-Cas9 edits mutations in the hemoglobin genes. It returns the ability of hemoglobin to capture oxygen and restores the healthy shape of RBCs.

Switching on unused genes

Another approach involves using CRISPR-Cas9 to switch on a gene which encodes a different kind of hemoglobin known as fetal hemoglobin. This type of hemoglobin typically only works during fetal development!

Shortly after the birth of a baby, their RBCs discontinue making fetal hemoglobin and replaces it with “adult” hemoglobin. If you have adult hemoglobin that contains SCD mutations, a switch to your fetal hemoglobin can help twist the balance back into healthy RBCs.

Other possibilities for CRISPR-Cas9 sickle cell therapies are available but they are yet to receive approval for clinical trials.

Though gene therapy for SCD is not yet available for most people currently, this may change soon. Various late-stage trials are underway, and some indicate early successful results.


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