BetaGlobin

Betaglobin, commonly known as beta-globin, is one of the globin subunits of adult hemoglobin (HbA). It is encoded by the HBB gene on chromosome 11. In adult humans, HbA consists of two alpha-globin and two beta-globin chains, along with four heme groups, forming the hemoglobin tetramer that transports oxygen from the lungs to tissues. Beta-globin is produced in erythroid cells of the bone marrow, with levels increasing after birth as fetal gamma-globin declines.

Beta-globin is a 146-amino-acid polypeptide that belongs to the globin family. It folds into the characteristic globin helical structure and contains a heme prosthetic group with an iron ion capable of reversible oxygen binding. The oxygen affinity of hemoglobin is modulated by allosteric effectors such as 2,3-bisphosphoglycerate, which helps regulate oxygen delivery to tissues.

Genetic variation in the HBB gene can cause disease. Mutations may lead to beta-thalassemia, characterized by reduced or absent beta-globin synthesis, or sickle cell disease (HbS), caused by a Glu6Val substitution that produces abnormal hemoglobin. Carriers often have mild or no symptoms, while disease severity depends on other genetic and regulatory factors, including the balance of other globin chains and fetal hemoglobin levels. Developmental regulation includes switching from gamma- to beta-globin expression after birth, with epsilon- and gamma-globin expressed during fetal life.

Diagnosis typically involves genetic testing and hemoglobin analysis. Treatments for related disorders range from regular transfusions and iron chelation to emerging gene therapies aimed at correcting HBB mutations or reactivating fetal gamma-globin production.

Beta-like globin genes reside in a cluster on chromosome 11 and evolved from common ancestral globin genes, distinct from the alpha-globin cluster on chromosome 16.