A potential genetic causal link between smoking behaviors and psoriasis was identified in a Mendelian randomization (MR) study published in the British Journal of Dermatology.
Investigators from Hangzhou Medical College in China sourced data for this study from the genome-wide association study (GWAS) and Sequencing Consortium of Alcohol and Nicotine use (GSCAN), the United Kingdom (UK) Biobank, 23andMe, and FinnGen. Genetic variables about alcohol consumption (n=941,280), smoking initiation (n=1,232,091), cigarettes smoked per day (n=337,334), smoking cessation (n=542,219), and lifetime smoking (n=462,690) were compared with genetic instruments for psoriasis among 13,299 patients and 21,543 control participants in the test sample and 4510 patients and 212,242 control participants in the replication sample.
The number single nucleotide polymorphisms (SNPs) tested was 99 for alcohol consumption, 378 for smoking initiation, 55 for cigarettes smoked per day, 126 for lifetime smoking, 24 for smoking cessation, and 58 for psoriasis, respectively.
A genetic correlation between psoriasis and smoking initiation (r, 0.152; P =5.9×10-8), cigarettes smoked per day (r, 0.139; P =4.3×10-5), lifetime smoking (r, 0.171; P =8.27×10-8), and smoking cessation (r, 0.217; P =2×10-4) were observed. The genetic correlation between alcohol consumption and psoriasis did not reach the Bonferroni threshold for significance (r, 0.067; P =.028).
The combined statistic from the test and replication samples indicated a significant association between psoriasis and smoking initiation (odds ratio [OR], 1.46; 95% CI, 1.32-1.60; P =6.24×10-14) and lifetime smoking (OR, 1.96; 95% CI, 1.41-2.73; P =7.32×10-5) as well as a suggestive effect of smoking cessation (OR, 1.39; 95% CI, 1.07-1.79; P =.012).
In the sensitivity analyses, results were consistent with the main analysis, however, some evidence of pleiotropy was observed.
The reverse MR analysis did not suggest that psoriasis had an effect on alcohol consumption or smoking behaviors.
This study may have been limited by only having access to genetic instruments about 1 aspect of alcohol consumption.
These data indicated to the study authors that there may be some causal genetic link between smoking behaviors and psoriasis risk. Additional study was suggested to evaluate whether reducing smoking may have a beneficial effect on psoriasis symptoms.
Reference
Wei J, Zhu J, Xu H, et al. Alcohol consumption and smoking in relation to psoriasis: a Mendelian randomization study. Br J Dermatol. Published online June 28, 2022. doi:10.1111/bjd.21718
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