Has modern science found a cure for sickle cell disease through the use of gene splicing? That’s the question on the minds of approximately 100,000 Americans who have the disease after the story of a teenager at Necker Children’s Hospital in Paris made news this month.
A Remarkable Result
The young man started experimental gene therapy at age 13 and received treatment for 15 months. Since that time, he has had no pain or complications, and has required no transfusions. He no longer takes medication and his blood shows no signs of the disease. In essence, he has been cured. Or so the evidence suggests at this point, but researchers say that long term follow up is needed to be certain. Dr. Marina Cavazzano, senior author of the study and head of Necker’s biotherapy department, is optimistic that this gene therapy treatment will be available in five years for patients with sickle cell disease.
One important benefit of gene therapy is that an outside donor is unneccessary. The patient is his own donor. This means no waiting to find a match for a donor and no chance of a rejection of the donation.
A Horrific Disease
Sickle Cell Disease is not something you would wish on even your worst enemy, and yet, it is one of the most common genetic disorders in the world. You don’t have to look far to find examples of people living with the disease. Celebrities both past and present have struggled with this illness, including
- Miles Davis
- Larenz Tate
- Tionne “T-Boz” Watkins
- Tiki Barber
- Paul Williams
- Georgeanna Tillman Gordon
Each year more than 275,000 babies are born with it, most of them in sub-Saharan Africa. In the United States one in every 365 black children is born with the disease which is caused by a mutation that affects the shape of the blood’s hemoglobin. Red blood cells carrying normal hemoglobin are flexible disc shaped cells that zip around your body, transporting oxygen wherever it is needed. Sickle hemoglobin is stiff and crescent shaped. This single mutation creates a host of problems that range from anemia to stroke.
A Good Candidate for Cure
There are over 3000 genetic disorders out there that are a result of mistakes in our DNA, something either wrongly left out, inserted, or changed. What is it about Sickle Cell Disease that made it possible to use genetic engineering to find a possible cure? Three important things. In Sickle Cell Disease:
- the affected gene is a known gene
- the affected gene can be replaced with a healthy modified version
- the cells that need to be changed are easy to get from the bone marrow
In Paris this trio of conditions allowed doctors to harvest stem cells from the teen’s own bone marrow and modify the genetic code to produce normal, healthy hemoglobin. Four days of chemotherapy treatments were used to kill the diseased cells, and then an IV was used to inject the modified cells into the patient’s bloodstream. As a result, the boy’s body began to produce normal blood cells.
Unfortunately, not all genetic diseases are this amenable to manipulation.
American Council on Science and Health’s Senior Fellow in Molecular Biology, Dr. Julianna LeMieux, points out, “This one success story is incredibly encouraging for the sickle cell community and for moving the field of curing diseases using genetic editing forward.”
But it’s not all smooth sailing on the sea of disease eradication. In addition to the problem of developing the technology to treat and cure both genetic and acquired diseases with genetic engineering, there is also the problem of ethics.
Prof. Eric S. Lander of Harvard Medical School and MIT, as well as the founding director of the Broad Institute, believes HIV, some forms of genetic blindness, Sickle Cell Anemia, familial hypercholesterolemia, and hemophilia could be completely eliminated when the necessary technology is developed. These disorders are good candidates for development because they avoid the thorny ethical issues such as embryo editing by simply editing the individual’s own genes.
Another ethical consideration is the high cost of these treatments and access to care. A cure is a wonderful thing but then the question becomes how will people in impoverished areas gain access to these expensive treatments?
What The Future
Genetic Engineering holds great promise for providing cures and treatments for other diseases. But it’s complicated and we’re in the early days. At this point most of the successes have been with treating inherited blood diseases. So far we’re not “fixing” any genes, we’re just adding working genes with the hopes that they will overcome the problem. Still, there is reason for optimism. We live in an age of medical miracles, from antibiotics to organ transplant to gene therapy, and who knows what marvels are yet to come.