Genetic association between COPD and polymorphisms in TNF, ADRB2 and EPHX1.

There is evidence of a hereditary component in chronic obstructive pulmonary disease (COPD). A number of genetic association studies have been performed to find susceptibility genes of COPD. The current authors performed a case-control, genetic-association study and a meta-analysis of 16 studies, involving seven polymorphisms in three well-studied genes: microsomal epoxide hydroxylase (EPHX1); tumour necrosis factor; and beta2-adrenoreceptor. A total of 492 Caucasian smokers and former smokers were recruited from hospital databases and population cohort studies. In the present study, a protective effect of the EPHX1 Tyr113His polymorphism was found (homozygous odds ratio (OR) 0.5). In the meta-analysis, homozygotes for this single nucleotide polymorphism (SNP) also had a pooled OR of 0.5. The same effect has been found in several lung cancer studies. Effects for other candidate SNPs were weak or statistically insignificant, and probable genotyping error was common. In conclusion, the present data and meta-analysis support a role for microsomal epoxide hydroxylase in the aetiology of chronic obstructive pulmonary disease.