How many people have alpha-thalassemia?
Alpha-thalassemia is caused by changes in the HBA1 and/or HBA2 genes. We each have two copies of HBA1 and HBA2, for a total of four copies. Up to 5% of the world's population has a change in at least one copy of these genes. However, these individuals typically have ancestors from Southeast Asia or the Mediterranean regions of the world.
Piel, F. & Weatherall, D. (2014). The alpha-thalassemias. The New England Journal of Medicine, 1908-1916. doi: 10.1056/NEJMra1404415
Vichinsky, E. (2012). Advances in the treatment of alpha-thalassemia. Blood Reviews, S31-S34. http://www.sciencedirect.com/science/article/pii/S0268960X12700103