Haptoglobin: function and polymorphism.

Haptoglobin is an acute phase protein capable of binding haemoglobin, thus preventing iron loss and renal damage. Haptoglobin also acts as an antioxidant, has antibacterial activity and plays a role in modulating many aspects of the acute phase response. There are 3 major haptoglobin phenotypes--Hp(1-1), Hp(2-1) and Hp(2-2). Possession of a particular phenotype has been associated with a variety of common disorders (e.g. cardiovascular disease, autoimmune disorders, malignancy), a fact which can only be explained by the idea that possession of a particular phenotype offers some protection against the development of these disorders. Knowledge of phenotype could therefore aid in the prognosis of disease and allow treatment to be better tailored to suit an individuals' needs.