BIOLOGICAL AND CLINICAL-SIGNIFICANCE OF HAPTOGLOBIN POLYMORPHISM IN HUMANS

Haptoglobin is a hemoglobin-binding protein expressed by a genetic pol ymorphism as three major phenotypes: 1-1, 2-1, and 2-2. Most attention has been paid to determining haptoglobin phenotype as a genetic finge rprint used in forensic medicine. More recently, several functional di fferences between haptoglobin phenotypes have been demonstrated that a ppear to have important biological and clinical consequences. Haptoglo bin polymorphism is associated with the prevalence and clinical evolut ion of many inflammatory diseases, including infections, atheroscleros is, and autoimmune disorders. These effects are explained by a phenoty pe-dependent modulation of oxidative stress and prostaglandin synthesi s. Recent evidence is growing that haptoglobin is involved in the immu ne response as well. The strong genetic pressure favoring the 2-2 phen otype suggests an important role of haptoglobin in human pathology.