Interaction of glutathione peroxidase-1 and selenium in endemic dilated cardiomyopathy.

Keshan disease (KD) is a fatal dilated cardiomyopathy with unknown etiology. We studied the gene-environment interaction in the pathogenesis of KD by assessing the association of low blood selenium and polymorphisms in glutathione peroxidase-1 (GPx-1) gene. The concentration of blood selenium and the activity and polymorphisms of GPx-1 in 71KD patients and 290 controls were measured. The functions of rat neonatal cardiomyocytes resulting from overexpression of 2 variants of GPx-1 were studied. Blood concentration of selenium and GPx-1 activity were lower in patients than in controls. Genetic analysis revealed a single nucleotide polymorphism (Pro198Leu) in GPx-1 gene associated with selenium deficiency as well as impaired GPx-1 activity. Gene-environment interaction analysis revealed a synergistic-multiplicative interaction between polymorphism of GPx-1 and selenium deficiency. Overexpression of the GPx-1 leucine-containing allele in cultured cardiomyocytes caused a 30% reduction in selenium-induced GPx-1 activity and increased serum starvation induced apoptosis as compared with that of the wild-type variant 198Pro. Selenium deficiency in carriers with the GPx-1 leucine-containing allele is associated with low GPx-1 enzyme activity, which may, in turn, increase the incidence of KD. Results from this unique disease may have broad implications for a gene-environment reaction in the etiology of other diseases.