The biochemical response to ursodeoxycholic acid (UDCA)—so‐called “treatment response”—strongly predicts long‐term outcome in primary biliary cholangitis (PBC). Several long‐term prognostic models ...based solely on the treatment response have been developed that are widely used to risk stratify PBC patients and guide their management. However, they do not take other prognostic variables into account, such as the stage of the liver disease. We sought to improve existing long‐term prognostic models of PBC using data from the UK‐PBC Research Cohort. We performed Cox's proportional hazards regression analysis of diverse explanatory variables in a derivation cohort of 1,916 UDCA‐treated participants. We used nonautomatic backward selection to derive the best‐fitting Cox model, from which we derived a multivariable fractional polynomial model. We combined linear predictors and baseline survivor functions in equations to score the risk of a liver transplant or liver‐related death occurring within 5, 10, or 15 years. We validated these risk scores in an independent cohort of 1,249 UDCA‐treated participants. The best‐fitting model consisted of the baseline albumin and platelet count, as well as the bilirubin, transaminases, and alkaline phosphatase, after 12 months of UDCA. In the validation cohort, the 5‐, 10‐, and 15‐year risk scores were highly accurate (areas under the curve: >0.90). Conclusions: The prognosis of PBC patients can be accurately evaluated using the UK‐PBC risk scores. They may be used to identify high‐risk patients for closer monitoring and second‐line therapies, as well as low‐risk patients who could potentially be followed up in primary care. (Hepatology 2016;63:930–950)
Genome-wide association studies in primary biliary cholangitis (PBC) have failed to find X chromosome (chrX) variants associated with the disease. Here, we specifically explore the chrX contribution ...to PBC, a sexually dimorphic complex autoimmune disease.
We performed a chrX-wide association study, including genotype data from 5 genome-wide association studies (from Italy, United Kingdom, Canada, China, and Japan; 5244 case patients and 11,875 control individuals).
Single-marker association analyses found approximately 100 loci displaying P < 5 × 10–4, with the most significant being a signal within the OTUD5 gene (rs3027490; P = 4.80 × 10–6; odds ratio OR, 1.39; 95% confidence interval CI, 1.028–1.88; Japanese cohort). Although the transethnic meta-analysis evidenced only a suggestive signal (rs2239452, mapping within the PIM2 gene; OR, 1.17; 95% CI, 1.09–1.26; P = 9.93 × 10–8), the population-specific meta-analysis showed a genome-wide significant locus in East Asian individuals pointing to the same region (rs7059064, mapping within the GRIPAP1 gene; P = 6.2 × 10–9; OR, 1.33; 95% CI, 1.21–1.46). Indeed, rs7059064 tags a unique linkage disequilibrium block including 7 genes: TIMM17B, PQBP1, PIM2, SLC35A2, OTUD5, KCND1, and GRIPAP1, as well as a superenhancer (GH0XJ048933 within OTUD5) targeting all these genes. GH0XJ048933 is also predicted to target FOXP3, the main T-regulatory cell lineage specification factor. Consistently, OTUD5 and FOXP3 RNA levels were up-regulated in PBC case patients (1.75- and 1.64-fold, respectively).
This work represents the first comprehensive study, to our knowledge, of the chrX contribution to the genetics of an autoimmune liver disease and shows a novel PBC-related genome-wide significant locus.
Display omitted
PDF
