Protein's Role Suggests Treatment for Thalassemia

A protein called alpha hemoglobin stabilizing protein, AHSP, isolated from the blood has been shown to bind and stabilize the alpha globin subunit of hemoglobin preventing it from forming a precipitate that damages red blood cells. This research was reported in the June 13, 2002, issue of Nature.


An excess of unstabilized alpha globin characterizes the inherited blood disorder beta thalasssemia, which affects some 300,000 patients worldwide. "AHSP acts as a chaperone molecule, a chemical that helps another protein to fold or unfold,” said Dr. Mitchell Weiss from The Children's Hospital of Philadelphia (PA, USA; www.chop.edu). "Here it makes free alpha globin stable and prevents its deleterious effects.”

Investigators studied the role of ASHP by using a strain of mice that had been genetically engineered to lack the gene that produces AHSP. The mice developed the reticulocytosis and abnormal erythrocyte morphology that is typical of thalassemia.

The protective function of AHSP could explain why it is that some patients who carry the genetic trait for beta thalassemia have mild disease and few symptoms even though their bodies produce more alpha than beta globin. However, if AHSP does not function properly, the excess alpha globin precipitation may change milder or intermediate thalassemia into more severe disease.

Research efforts will now focus on methods to increase production of ASHP in patients with thalassemia. "If we can reduce the buildup of free alpha globin, we may be able to lower the dose of [blood] transfusion needed and improve patients' quality of life,” added Dr. Weiss.





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