HBA2

Hemoglobin, alpha 2 also known as HBA2 is a is_associated_with::gene that in humans codes for the alpha globin chain of is_associated_with::hemoglobin.

Function
The human alpha globin gene cluster located on chromosome 16 spans about 30 kb and includes seven alpha like globin genes and pseudogenes: 5'- is_associated_with::HBZ - HBZP1 - HBM - HBAP1 - HBA2 - is_associated_with::HBA1 - is_associated_with::HBQ1 -3'. The HBA2 (α2) and  HBA1 (α1) coding sequences are identical. These genes differ slightly over the 5' untranslated regions and the introns, but they differ significantly over the 3' untranslated regions. Two α-chains plus two-β chains constitute HbA, which in normal adult life comprises about 97% of the total is_associated_with::hemoglobin; alpha chains combine with delta chains to constitute HbA-2, which with HbF (fetal hemoglobin) makes up the remaining 3% of adult hemoglobin. Alpha thalassemias result from deletions of each of the alpha genes as well as deletions of both HBA2 and HBA1; some nondeletion alpha is_associated_with::thalassemias have also been reported.