Study Identifies Unidirectional Link Between Primary Biliary Cirrhosis and Psoriasis Risk

A new study, published in Frontiers, using bidirectional Mendelian randomization (MR) analysis has revealed a causal relationship between primary biliary cirrhosis (PBC) and psoriasis, identifying PBC as a risk factor for the development of psoriasis, but not vice versa.

The analysis applied 4established MR methods—inverse-variance weighted (IVW), MR-Egger regression, weighted median, and weighted mode—across genetic datasets to evaluate the potential directionality of the association. Results from the IVW method confirmed a statistically significant causal effect of PBC on psoriasis (odd ratio [OR]: 1.081; 95% CI: 1.028–1.137; P < 0.05), suggesting that individuals with a genetic predisposition to PBC have a higher likelihood of developing psoriasis.

“The causal relationship between the risk of PBC and psoriasis was identified, as confirmed by IVW analysis,” the study stated. “The other 3 MR methods also produced similar results,” reinforcing the robustness of the findings.

Importantly, the reverse association—psoriasis increasing the risk of PBC—was not supported by the data (OR: 1.022; 95% CI: 0.935–1.118; P > 0.05). Sensitivity analyses, including MR-Egger intercept and leave-one-out tests, found no significant evidence of horizontal pleiotropy, further validating the causal inference.

“The intercept of MR-Egger regression was 0.0013 (P > 0.05), indicating that genetic pleiotropy did not influence the results,” the authors noted.

For dermatologists, these findings underscore the importance of systemic disease awareness, particularly when managing patients with PBC. While psoriasis is primarily a skin disorder, this study suggests that underlying hepatic autoimmune pathology may play a contributory role in disease onset for some individuals.

“This potential causal relationship offers a new perspective on the etiology of PBC,” the study concluded.

Clinicians may consider enhanced dermatologic screening for patients with PBC, particularly in cases where cutaneous symptoms emerge or worsen. Further studies could help clarify shared pathogenic pathways and inform early intervention strategies.

Reference
Zhao D, Zhao Q, Xu F, Zhang F, Bai W. Primary biliary cirrhosis and psoriasis: a two-sample Mendelian randomization study. Front Immunol. 2024;14:1264554. doi:10.3389/fimmu.2023.1264554