Alpha and Beta Globin Genes Quiz

Overview of Globin Genes and Hemoglobin Production

• The alpha globin locus is located on chromosome 16 and consists of four genes that contribute to the synthesis of the alpha globin protein.
• The beta globin locus is shown in the upper panel and includes two gamma globin genes that are active during fetal growth and produce hemoglobin F (HbF).
• Hemoglobin F is composed of two alpha globin chains and two gamma globin chains (alpha2gamma2) and is primarily present during fetal development.
• The production of embryonic hemoglobins (Hbs) is mainly attributed to yolk sac erythroblasts during the early stages of embryogenesis.
• Embryonic Hbs, such as Gower I, Portland, and Gower II, consist of embryonic globin chains including zeta and epsilon.
• Fetal Hb (HbF) replaces embryonic Hbs around the 14th week of gestation and is the predominant form of hemoglobin during this period.
• HbF has a higher affinity for oxygen compared to adult hemoglobin.
• After birth, the "adult" gene, beta, takes over and produces the majority of hemoglobin.
• The production of different types of hemoglobins occurs at specific stages of embryonic, fetal, and postnatal life.
• Severe alpha thalassemia may result in trace amounts of embryonic Hbs being present beyond the early stages of embryogenesis.
• The lower panel of the image represents the alpha globin locus, while the upper panel represents the beta globin locus.
• Understanding the regulation and expression of globin genes is crucial for comprehending normal and abnormal hemoglobin production.