HBA1

About HBA1

HBA1 and its near identical neighbor HBA2, both in the alpha globin cluster on chromosome 16p13.3, encode alpha globin, which pairs with beta globin to form adult hemoglobin A. Because each person normally carries four alpha globin genes, two on each chromosome 16, the severity of alpha thalassemia depends on how many are deleted or inactivated. Loss of one gene is usually silent, two produces alpha thalassemia trait with mild anemia, three causes hemoglobin H disease, and loss of all four causes hemoglobin Bart hydrops fetalis, which is usually fatal before or shortly after birth without intervention. Alpha thalassemia is common in Southeast Asia, Africa, the Mediterranean, and the Middle East, regions where carriers are thought to have had some protection against malaria. Most variants are deletions rather than point mutations.