Mendelian randomization study of the genetic interaction between psoriasis and celiac disease

Epidemiological studies have observed some relationship between psoriasis and celiac disease (CD), while the causal link between these 2 autoimmune diseases was unclear. In the current study, we aimed to explore the causal link between psoriasis and celiac disease with bidirectional 2-sample Mendelian Randomization (MR) study. Eligible instrument variables (IVs) with genome-wide significance (p < 5E-08) were extracted from the summary-level datasets from the published genome-wide association studies (GWAS), which were conducted in the European population. The inverse variance weighted (IVW) method was performed as the main analysis, sensitivity analyses and post-MR analyses were also performed. Our MR analyses found that genetically doubling the odds of CD would increase the risk for psoriasis (p = 1.58e-03, OR [95% CI] 1.232 [1.061-1.432]). And the results were supported by sensitivity analyses. While we found that genetically determined psoriasis was not associated with the risk for CD (IVW: p = 0.985, OR [95% CI] 1.000 [0.965-1.037]). Our study provided novel genetic evidence that patients with CD were at an increased risk of developing psoriasis, while psoriasis was not associated with the risk for CD. Clinicians should be aware of the associations and pay attention to skin manifestations in patients with CD.