HBA2 is a gene located on chromosome 16 that encodes a component of hemoglobin, the protein in red blood cells responsible for transporting oxygen. Specifically, HBA2 produces the alpha-globin subunit, which pairs with beta-globin subunits to form hemoglobin A, the most common type of hemoglobin in adults. Mutations in the HBA2 gene can lead to various forms of alpha-thalassemia, a blood disorder characterized by reduced production of alpha-globin chains. This condition can result in anemia and other health complications, depending on the severity of the mutations and the number of affected gene copies.