Convulsive disorder and genetic polymorphism. Association of idiopathic generalized epilepsy with haptoglobin polymorphism.

Haptoglobin is a polymorphic protein that is well known for its hemoglobin (Hb)-binding property. The protein shows gross differences in molecular size among genotypes, resulting in different degrees of diffusion in central nervous system tissue. Since the breakdown of erythrocytes in the intracerebral fluid results in Hb-mediated free OH radical formation, lipid peroxidation, and increased neuronal excitability, a differential diffusion of haptoglobin phenotypes in the intracerebral fluid might result in a different degree of protection from oxidative damage. We have studied two samples of children with idiopathic generalized epilepsy from two different Italian populations. In both samples the haptoglobin *1/*1 genotype is much less represented in epileptic children than in controls. These observations suggest that subjects carrying the Hp*1/*1 genotype, that has the lowest molecular size and diffuses more readily in the interstitial cerebral fluid, are more protected against idiopathic generalized epilepsy than those with other haptoglobin genotypes.