How Doctors Are Using CRISPR Gene-Editing to Treat Genetic Diseases

One of the first trials for the gene-editing technology known as CRISPR, which stands for Clustered Regularly Interspaced Short Palindromic Repeats, is underway in Nashville, TN, where doctors are using the technique to treat a patient with the genetic disorder sickle cell anemia.

While the technique has been used in China, this is the first time doctors in the U.S. have experimented using this technology on living humans. The technique has the potential to treat, if not cure, a range of genetic diseases and conditions, including blindness and several types of cancer.

Doctors used CRISPR to edit the patient’s genes for this initial U.S. trial, effectively eradicating the mutation causing the genetic disease. However, the long-term effects of editing human genomes has yet to be studied. Find out how doctors are utilizing this ground-breaking new treatment.

A Potential Cure for Blood Disorders

Sickle cell anemia, or sickle cell disease, is caused by a mutation in the gene that makes hemoglobin, which causes red blood cells to collapse into the shape of a sickle. This makes it difficult for red blood cells to move through the body’s cardiovascular system, which can lead to  a range of health complications.

Hemoglobin is only produced by a fetus in the womb and by infants for a short duration after they’ve been born. Patients born with sickle cell anemia often experience intense pain and are at high risk for strokes and heart attacks. Typically, these patients will undergo blood transfusions to avoid blood clots, but complications can easily occur.

During the first CRISPR trial, doctors took billions of cells out of the bone marrow of the patient, modified the cells to stimulate the growth of hemoglobin, and then infused the cells back into the patient’s body. They hope to eventually change the shape of the red blood cells so they can move freely throughout the patient’s bloodstream.

The first patient had to go through chemotherapy, which removed their bone marrow cells. Then, doctors added the modified cells back into their system. With the trial still underway, doctors are closely monitoring the patient’s health to make sure the edited cells are functioning properly. More trials have also been announced with doctors planning to study dozens of patients across Canada and Europe.

Treating Blindness with Gene-Editing Technology

Doctors are also experimenting with using CRISPR to treat blindness. The illness, officially known as Leber congenital amaurosis 10 (LCA10), is caused by a genetic mutation in the outer portion of the eye’s photoreceptor cells, which are responsible for transmitting light signals to the brain where they are interpreted as sight. As a single-gene disease, LCA10 is an ideal candidate for early CRISPR trials. Doctors can use this technology to essentially cut out the mutation causing the disease, allowing the photoreceptor cells to function properly.

Editas Medicine, a genome editing company and Allergan, a pharmaceutical company, will use this technique in the first set of trials in the U.S., and are currently enrolling patients born with a congenital vision disease. Doctors will use CRISPR to snip the patient’s genes in a set of predetermined locations in order to remove the mutated gene. If the technique proves successful, Editas and Allergan eventually plan on including patients as young as three years old in the trials.

The procedure will be performed during outpatient surgery, when the surgeon will inject the gene-editing tool into the retina and begin splicing the mutated genes. The tool will be encased in a deactivated adenovirus, which will deliver the splicing payload to the photoreceptor cells. Compared to other early CRISPR trials, the risks are relatively low. Even if the surgeon accidentally unloads the tool into other cells, it poses no biological harm to the patient.

Once the procedure is complete, the team will use vision tests to measure the results. They will also record the patients walking through a maze to see if the technique was successful.

As promising as these early gene-editing techniques sound, it may take months or even years for doctors to know whether these early trials were successful. If all goes well, genetic diseases may one day be a thing of the past. Even as the long-term effects of this procedure remain unclear, CRISPR is giving hope to many who previously had none.

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