A potential causal genetic link between smoking behaviors and psoriasis

A potential genetic causal link between smoking behaviors and psoriasis has been identified in a Mendelian randomization (MR) study published in the British Journal of Dermatology.

Investigators from Hangzhou Medical College in China extracted data for this study from the Genome-Wide Association Study (GWAS) and the Sequencing Consortium of Alcohol and Nicotine Use (GSCAN), United Kingdom (UK) ) Biobank, 23andMe and FinnGen. Genetic variables regarding 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 4,510 patients and 212,242 control participants in the replication sample.

The number of single nucleotide polymorphisms (SNPs) tested were 99 for alcohol consumption, 378 for smoking initiation, 55 for cigarettes smoked daily, 126 for lifelong smoking, 24 for smoking cessation, and 58 for psoriasis, respectively.

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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 Bonferroni’s level of significance (r, 0.067; P =.028).

The combined statistic of the test and replicate 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 an effect suggestive of smoking cessation (OR, 1.39; 95% CI, 1.07-1.79; P =.012).

In sensitivity analyses, results were consistent with the primary analysis, however, some signs of pleiotropy were observed.

Reverse MRI analysis did not suggest that psoriasis had any effect on alcohol consumption or smoking behaviors.

This study may have been limited by having access to genetic instruments on only one aspect of alcohol consumption.

These data indicated to the study authors that there may be a causal genetic link between smoking behaviors and the risk of psoriasis. One additional study has been suggested to assess whether reducing smoking may have a beneficial effect on psoriasis symptoms.


Wei J, Zhu J, Xu H, et al. Alcohol consumption and smoking in relation to psoriasis: a randomized Mendelian study. Br J Dermatol. Published online June 28, 2022. doi:10.1111/bjd.21718

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