Polymeric structure of protein products resulting from the three Hp genotypes: Hp 1-1, Hp 2-1, and Hp 2-2. All of the subunits in the polymers are disulfide bond linked through the alpha chain. Individuals homozygous for the Hp 1 allele form exclusively dimers containing two Hp 1 subunits. Heterozygotes form linear polymers containing a variable number of internal Hp 2 subunits flanked by two Hp 1 subunits at either end. Individuals homozygous for the Hp 2 allele form cyclic polymers of varying numbers of Hp 2 subunits. The molecular weight of the polymers is smallest for Hp 1-1 at 80 kD, larger for Hp 2-1 ranging from 86–300 kD, and largest for Hp 2-2 ranging from 170–900 kD. Figure included with permission from Mary Ann Liebert, Inc. publishers (Levy et al, Antioxid Redox Signal 2010; 12:293–304).