2017/02/05

Sickle cell mutation is not beneficial

Scientists try to fix the mutation that causes sickle cell disease


Excerpt: "Scientists have taken an important step toward using CRISPR-Cas9 genome-editing to cure sickle cell disease, repairing the disease-causing mutation in blood-forming cells taken from patients. Some edited cells, injected into lab mice, both survived in the animals’ bone marrow and turned into red blood cells — a hint that CRISPR’d cells would would produce healthy hemoglobin in people. This is the first such experiment to get levels of healthy hemoglobin that might be high enough to cure patients.

Sickle cell is a painful and sometimes fatal disease that affects about 100,000 people in the US. Many scientists consider it an embarrassment that, although the mutation responsible for sickle cell was discovered in 1949, the revolution in molecular biology and genetics has hardly touched it.

That is finally changing. Researchers at Dana-Farber/Boston Children’s Hospital and elsewhere have reported enough progress in cell and animal experiments with virus-based gene editing to plan a human study of at least one genome-editing strategy in a few months. The new study, published on Wednesday in Science Translational Medicine, takes a different approach, increasing the chance that something will eventually be able to engineer blood cells so they produce healthy hemoglobin rather than the mutated, sickled kind.

CRISPR did as it was programmed to. In about one-quarter of cells, the guide RNA made a beeline for the mutation, Cas9 snipped out the mutation, and the cell used the repair template to insert a healthy version. In the other cells, the editing didn’t take, which is typical for CRISPR."


My comment: Why do scientists try to eliminate the sickle cell mutation? Because it's very harmful when inherited from both parents. Millions of people suffer from SCD worldwide and it causes heavy costs for the economy:

https://www.cdc.gov/ncbddd/sicklecell/data.html

"SCD is a major public health concern. From 1989 through 1993, an average of 75,000 hospitalizations due to SCD occurred in the United States, costing approximately $475 million.
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There is not such a thing as a beneficial random mutation. But scientists have discovered about 200,000 genetic mutations that cause diseases within humans. 10,000 new genetic disease causing mutations are discovered every year, but there are no signs of human evolution. The evolutionary theory is a major lie. Don't get lost.