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The following is a summary of “Primary biliary cholangitis has causal effects on systemic rheumatic diseases: a Mendelian randomization study,” published in the August 2024 issue of Gastroenterology by Zhang et al.

Observational studies have linked primary biliary cholangitis (PBC) and systemic rheumatic diseases (SRDs), but the exact cause-and-effect relationship between the conditions remains uncertain.

Researchers conducted a retrospective study evaluating the impact of PBC on SRD using Mendelian randomization (MR) analysis.

They obtained the genome-wide association study (GWAS) summary data from the MRC IEU OpenGWAS and FinnGen databases. Independent genetic variants for PBC were selected as instrumental variables. Inverse variance weighting was used to assess the causal impacts of PBC on Sjögren syndrome (SS), rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), systemic sclerosis (SSc), mixed connective tissue disease (MCTD), and polymyositis (PM). Horizontal pleiotropy and heterogeneity were measured using the MR‒Egger intercept test and Cochran’s Q value.

The results showed PBC had causal effects on SS (OR = 1.177, P=8.02e-09), RA (OR = 1.071, P=9.80e-04), SLE (OR = 1.447, P=1.04e-09), SSc (OR = 1.399, P=2.52e-04), MCTD (OR = 1.306, P=4.92e-14), and PM (OR = 1.416, P=1.16e-04). The MR‒Egger intercept tests indicated no horizontal pleiotropy (all P values>0.05). The leave-one-out method confirmed the robustness of the findings.

Investigators concluded that the study revealed potential relationships between PBC and several SRDs.

Source: bmcgastroenterol.biomedcentral.com/articles/10.1186/s12876-024-03319-3