An association study on the CHRNA5/A3/B4 gene cluster, smoking and psoriasis vulgaris.

Genome-wide association and large cohort studies have consistently linked several single nucleotide polymorphisms (SNPs) located in the CHRNA5/A3/B4 gene cluster to smoking behaviors and nicotine dependence. Smoking is one of the well-established environmental risk factors for psoriasis and also associated with severity of the disease. Then we conduct the study to examine whether the genetic variations related to smoking behavior located in the CHRNA5/A3/B4 gene cluster also predict the risk of psoriasis vulgaris (PV). The investigations may help explain the mechanisms of the smoking-PV relationship. This is a hospital base case-control study including 634 subjects (329 PV patients and 305 controls), all Chinese Han population. 8 SNPs were selected based on findings from recent studies on smoking and nicotine dependence, all located in the nicotinic acetylcholine receptor subunits CHRNA5/A3/B4 gene cluster. The variants were typed by SNaPshot Multiplex Kit (Applied Biosystems Co., USA). We confirmed that smoking, alcohol consumption and higher body mass index (BMI ≥25) were risk factors for PV. However, none of the selected SNPs was associated with PV risk in the overall analysis and stratification analysis. And we found no association between the selected SNPs in CHRNA5/A3/B4 gene cluster and the clinical features of PV in case-only analysis. This exploratory study does not provide a relationship between these smoking-related SNPs in the CHRNA5/A3/B4 gene cluster and PV in Chinese Han population.