Thalassemia is a group of related inherited disorders that together are the most common single-gene disease known. The most severe form of the disease, beta thalassemia major, affects 300,000 patients worldwide.
Thalassemia results from an imbalance between two proteins in hemoglobin, called alpha and beta globin. An excess of either type of protein is toxic, causing thalassemia symptoms including poor growth, fatigue, bone damage, or skin ulcers. The newly found protein, alpha hemoglobin stabilizing protein (AHSP), binds to free alpha globin and prevents it from forming a precipitate that damages red blood cells.
AHSP acts as a chaperone molecule a chemical that helps another protein to fold or unfold, said Mitchell Weiss, M.D., Ph.D., a pediatric hematologist at The Childrens Hospital of Philadelphia, and senior author of the paper, published in the June 13 issue of Nature. Here it makes free alpha globin stable and prevents its deleterious effects.
Dr. Weiss team suspected that AHSP, by preventing free alpha hemoglobin from precipitating within red blood cells, protects the cells from injury. To test that hypothesis, the researchers developed knockout mice, animals genetically engineered to lack the gene that produces AHSP. Those mice showed blood abnormalities similar to those found in mice with thalassemia.
AHSPs protective role could explain how 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. By binding to free alpha globin, AHSP ma
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Contact: John Ascenzi
Ascenzi@email.chop.edu
215-590-7332
Children's Hospital of Philadelphia
12-Jun-2002