In the new study, led by Orkin and Sankaran, the team showed that BCL11A directly suppresses HbF production. When the researchers suppressed BCL11A itself in human red-blood-cell precursors, the cells began making HbF in large amounts.
"This is one of very few instances in the gene association field where one has been able to take a candidate gene and figure out what it's doing," says Orkin, the study's senior investigator who is also a professor of pediatrics at Harvard Medical School and chair of pediatric oncology at Dana-Farber. "It's pretty clear that this gene is a silencer of fetal hemoglobin. If you could knock it down to a low level, you could turn on fetal hemoglobin."
"The discovery of a single gene that profoundly affects fetal hemoglobin levels represents a major breakthrough in the quest for effective therapies for sickle cell disease and thalassemia," notes Elizabeth G. Nabel, MD, director of the National Heart, Lung, and Blood Institute (NHLBI) of the National Institutes of Health, which helped support the study. "Researchers can now direct their efforts at developing novel therapies aimed at a specific target that could dramatically alter the course of these often devastating blood disorders. This news should bring great hope to the millions of people worldwide affected by sickle cell disease and thalassemia."
Increasing levels of HbF would compensate for abnormal or insufficient adult hemoglobin in sickle-cell anemia or thalassemia, easing symptoms and in some cases achieving a virtual cure, the researchers say. The drug hydroxyurea, used in some patients with hemoglobin disorders, often raises HbF levels, but the increases are modest, it doesn't work in all patients, it can cause toxicity, and no one knows
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