Which type of thalassemia is characterized by an inherited absence or decreased production of the alpha chain?

Alpha thalassemia is characterized by an inherited absence or decreased production of the alpha globin chains of hemoglobin. In individuals with this condition, there is a mutation in the genes responsible for producing alpha chains, which can result in a spectrum of clinical presentations ranging from mild to severe anemia, depending on how many of the four alpha-globin genes are affected.

In its most severe form, called alpha thalassemia major, the lack of alpha chains leads to an excess of beta globin chains, which can form unstable hemoglobin tetramers known as Hemoglobin H or even result in fetal hydrops if there is a complete absence of alpha chain production. The diagnosis of alpha thalassemia is often supported by laboratory findings such as microcytic anemia and the presence of abnormal hemoglobin forms on electrophoresis.

Understanding the pathophysiology of alpha thalassemia is important for recognizing its clinical implications and management, distinguishing it from other hemoglobinopathies such as beta thalassemia, which is caused by a different genetic mechanism affecting the beta globin chains, or conditions like sickle cell disease and hemoglobin C disease that involve the production of abnormal hemoglobin.