Haptoglobin, in its simplest form, consists of two alpha and two beta chains, connected by disulfide bridges. The chains originate from a common precursor protein, which is proteolytically cleaved during protein synthesis. Hp exists in two allelic forms in the human population, so-called Hp1 and Hp2. Three phenotypes of Hp, therefore, are found in humans: Hp1-1, Hp2-1, and Hp2-2. Hp of different phenotype have been shown to bind hemoglobin with different affinities, with Hp2-2 being the weakest binder. Of the three haptoglobin phenotypes, Hp 1-1 is the most effective in binding free hemoglobin and in suppressing the inflammatory responses associated with free hemoglobin. Hp 1-1 protects against vascular complications in diabetes, is associated with sickle cell anemia, and is more common than other phenotypes in cases of cirrhosis. Individuals who are phenotype 1-1 have the highest concentration of haptoglobin in plasma.