Hemoglobin subunit alpha

Hemoglobin subunit alpha , also known as HBA1, is a hemoglobin protein that in humans is encoded by the "HBA1" gene.
Gene.
The human alpha globin gene cluster located on chromosome 16 spans about 30 kb and includes seven loci: 5'- zeta - pseudozeta - mu - pseudoalpha-1 - alpha-2 - alpha-1 - theta - 3'. The alpha-2 (HBA2) and alpha-1 (HBA1; this gene) 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.
Protein.
Two alpha chains plus two beta chains constitute HbA, which in normal adult life comprises about 97% of the total hemoglobin; alpha chains combine with delta chains to constitute HbA-2, which with fetal hemoglobin (HbF) makes up the remaining 3% of adult hemoglobin.
Clinical significance.
Alpha thalassemias result from deletions of each of the alpha genes as well as deletions of both HBA2 and HBA1; some nondeletion alpha thalassemias have also been reported.
Interactions.
Hemoglobin subunit alpha has been shown to interact with hemoglobin subunit beta (HBB).