Combined effect between CHRNB3-CHRNA6 region gene variant (rs6474412) and smoking in psoriasis vulgaris severity

Background: Many factors associated with causing psoriasis have been reported, such as the genetic and environmental factors. Smoking is one of the well-established environmental risk factors for psoriasis and also associated with the disease severity. In addition, several studies of psoriasis and psoriatic arthritis have documented gene-environment interactions involving smoking behavior. Although gene polymorphisms on nicotinic acetylcholine receptor subunits CHRNB3-CHRNA6 region gene have been found to correlate with smoking behavior and lung cancer susceptibility in Chinese Han population, the combined effect between the smoking-related genetic variants and smoking behavior on psoriasis vulgaris (PV) has been unreported. Objective: To evaluate the combined effect of the smoking-related (rs6474412-C/F) polymorphism on CHRNB3-CHRNA6 region gene and smoking behavior on PV risk and clinic traits in Chinese Han population. Methods: A hospital-based case-control study including 672 subjects (355 PV cases and 317 controls) was conducted. The variant of rs6474412 was typed by SNaPshot Multiplex Kit (Applied Biosystems Co., USA). Results: The higher body mass index (BMI 25), smoking behavior and alcohol consumption were risk factors for PV, and the estimated ORs were 1.55 (95% CI, 1.09-229), 1.74(95% CI, 122-2.49) and 1.81 (95% CI, 1.25-2.62) respectively. The smoking patients had more severe conditions than non-smokers (OR = 1.71, 95% CI, 1.082.70, P = 0.020). The alleles and genotypes of rs6474412 were not associated with risk of PV, but the combined effect of rs6474412 genotype (TT) and smoking behavior increased severity of PV (OR = 5.95; 95% CI, 13925.31; P<0.05; adjusted OR = 2.20; 95% CI, 1.55-3.14; P<0.001). Conclusions: Our results demonstrate that the combined effect of rs6474412-C/T polymorphism in smokingrelated CHRNB3-CHRNA6 region gene and smoking behavior may not confer risk to PV, but may have impact on PV severity in Chinese Han population. (C) 2014 Elsevier B.V. All rights reserved.