Sickle-cell anemia is an inherited disease characterized by red blood cells that are shaped like a sickle instead of a biconcave disk. The red blood cells also have a reduced ability to transport oxygen. The cause of sickle-cell anemia has been traced to an inherited mutation in the \beta -globin gene which is located on chromosome 11. Two alleles of the \beta -globin gene are: B allele: Results in red blood cells that are shaped as biconcave disks (normal) and function normally to transport oxygen. b allele: Results in sickle-shaped red blood cells and reduced oxygen transport.