Hemoglobin (Hb) is oxygen-binding metalloprotein that is present in the red blood cells. The most abundant Hb is HbA tetramer that is made up of two α, two β chains and the nonprotein heme group. The heme group contains iron ion and a porphyrin ring. Mutations in Hb gene result in hemoglobinopathies, the best known being sickle-cell disease and thalassemias.
