Can Gene Therapy Really Cure Sickle-Cell Disease (SCD) As Doctors Claim?

What are sickle-cell disease and sickle-cell anemia? Causes, prevention, and cure

Can Gene Therapy Really Cure Sickle-Cell Disease (SCD) As Doctors Claim?

According to a case report published Thursday in the New England Journal of Medicine (http://www.nejm.org/doi/10.1056/NEJMoa1609677#t=articleTop) a teenaged patient suffering from sickle-cell disease, a hemoglobin abnormality in the red blood cells, has apparently been cured of the dreaded disease after fifteen months of gene therapy.

The patient underwent the first ever experimental treatment for the affliction at the Necker Children’s Hospital in Paris and according to researchers; total remission was accomplished as the patient is now pain-free and does not require SCD medication any longer.

“Since therapy was applied, he hasn’t had any pain, any complications. He is free of any transfusions. He plays sports and goes to school,” said M.D. Philippe Leboulch, a professor of medicine at the University of Paris and co-author of the new research. “So we are quite pleased with the results.”

Although SCD patients are found all over the world, the highest concentration (about 80%) of cases occurs in sub-Saharan Africa. It is also relatively common in some parts of India, the Arabian Peninsula and in other parts of the world as well, especially among people of African ancestry living in these parts.

Sickle-cell disease (SCD)

Sickle-cell disease or SCD can be described as a group of blood disorders generally passed down from parents to offspring. SCD can be of several types, the most common being sickle-cell anemia (SCA) which is actually an aberration in the hemoglobin found in red blood cells. Hemoglobin is a kind of protein responsible for carrying oxygen to different organs of the body.

The abnormality causes the red blood cells, which is typically circular in shape, to mutate into rigid, sickle-shaped cells causing blockage in the blood flow thereby depleting the vital oxygen supply to body organs.

When two mutated copies of the hemoglobin gene are inherited, one from each parent, sickle-cell disease occurs. Stress, dehydration, temperature changes and high altitude are factors that can trigger SCD attacks.

Any person who inherits just one abnormal copy of the hemoglobin gene does not generally display symptoms of the disease but are called carriers – someone having sickle-cell trait.

Symptoms

The onset of SCD related complications characteristically occurs around 5-6 months after birth. The severity of the symptoms may vary from person to person.

Several health problems are likely to develop including bouts of pain medically known as sickle-cell crisis, anemia – hemoglobin abnormality in the blood affecting its oxygen carrying capability – bacterial infections, swelling in the hands and feet, and stroke. As SCD patients grow older, long-term or chronic pain may set in including severe complications with a high mortality rate.

Diagnosis

Sickle-cell disease is typically diagnosed by blood tests. Some countries have regulations in place to test all newborn babies. Diagnosis can also be performed on unborn babies from a sample of the amniotic fluid. Although blood samples from the fetus can also be taken for diagnosis, the amniotic fluid test is preferred as it involves less risk.

Neonatal screening has two advantages: Early detection of SCD in individuals and identification of people who may not have SCD but can be carriers with sickle-cell trait.

Prevention, Treatment, and Management

Vaccination and antibiotics will be decided by doctors and may vary from patient to patient.

High fluid intake is recommended to minimize the chances of dehydration which can trigger SCD attacks.

Folic acid supplementation is recommended daily for SCD sufferers and should be used for life. Penicillin is required to be used on children from birth up to five years of age as this is the period during which they are most vulnerable to infections and complications.

Pain medication is to be decided by the attending physician depending on the severity of the sickle-cell crisis.

Blood transfusion helps in the management of acute SCD cases. It can also be used as a preventive measure against complications from the disease as adding normal blood cells through transfusion reduces the number of cells that are likely to sickle. It also reduces the risk of first- stroke or even repeat strokes in patients who have already suffered one.

Hydroxycarbamide (hydroxyurea) is known to reduce the frequency and severity of attacks according to a 1995 study. It also increases the life expectancy of SCD sufferers according to another study conducted in 2003. It may have side effects when used over long periods of time but they are usually negligible.

Bone marrow transplant is particularly effective in children and is known to be the only cure for SCD, but it has its own shortcomings in that it has to, ideally, be from a close relative (allogenic) donor.

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