PSORIASIS and infection interact in a bidirectional manner, where certain infections could trigger psoriasis, while psoriasis is also associated with an increased risk of serious infections. However, there is currently limited evidence on the association between psoriasis and COVID-19. To address this gap, a research team at University of Ioannina, Greece, conducted an updated mendelian randomisation study to explore the relationship between COVID-19 and psoriasis, challenging previous work on this topic.
Summary statistics on psoriasis were obtained from the largest genome-wide association study on Europeans, along with several sensitivity analyses and genome-wide summary statistics from the COVID-19 Host Genetics Initiative. The genome-wide summary statistics meta-analysis of patients of European ancestry with psoriasis included 13,229 dermatologist-diagnosed cases and 21,543 controls. The mendelian randomisation analysis found no association between a genetic predisposition to psoriasis and an increased susceptibility to contracting COVID-19, even after correcting for outliers.
The ‘leave-one-single nucleotide polymorphism out’ analysis revealed no single influential nucleotide polymorphism, suggesting that having a predisposition to COVID-19 did not increase the risk of developing psoriasis. Further sensitivity analyses failed to support a causal association between psoriasis and the severity of COVID-19 infection. The results also challenge previous work that suggested a genetic predisposition to psoriasis is associated with a greater degree of susceptibility to contracting, being hospitalised, or developing severe illness because of COVID-19 in Europeans.
Overall, the research team hypothesised that their large sample size may be why their findings are not congruent with those of previous studies. Alternatively, psoriasis was self-reported in previous studies, leading to a high degree of misclassification, and they did not use the most recent COVID-19 data. In conclusion, the research team stated that their study does not support the causal relationship between a genetic predisposition to psoriasis and a higher susceptibility to being infected, hospitalised, or developing COVID-19 in Europeans.