By switching off the BCL11A gene, researchers at Harvard Medical School succeeded in eliminating sickle cell disease in mice, reports New Scientist's Charlie Harvey. The gene is responsible for switching the body's hemoglobin from the fetal form to the adult form, and since it's a mutant form of adult hemoglobin that causes the disease, knocking out BCL11A tricks the body into making fetal hemoglobin, and eliminates the condition, he adds.