Background and Aims: Inflammatory bowel disease [IBD] phenotypes are very heterogeneous between patients, and current clinical and molecular classifications do not accurately predict the course that IBD will take over time. Genetic determinants of disease phenotypes remain largely unknown but could aid drug development and allow for personalised management. We used genetic risk scores [GRS] to disentangle the genetic contributions to IBD phenotypes. Methods: Clinical characteristics and imputed genome-wide genetic array data of patients with IBD were obtained from two independent cohorts [cohort A, n = 1097; cohort B, n = 2156]. Genetic risk scoring [GRS] was used to assess genetic aetiology shared across traits and IBD phenotypes. Significant GRS-phenotype (false-discovery rate [FDR] corrected p <0.05) associations identified in cohort A were put forward for replication in cohort B. Results: Crohn's disease [CD] GRS were associated with fibrostenotic CD [R2 = 7.4%, FDR = 0.02] and ileocaecal resection [R2 = 4.1%, FDR = 1.6E-03], and this remained significant after correcting for previously identified clinical and genetic risk factors. Ulcerative colitis [UC] GRS [R2 = 7.1%, FDR = 0.02] and primary sclerosing cholangitis [PSC] GRS [R2 = 3.6%, FDR = 0.03] were associated with colonic CD, and these two associations were largely driven by genetic variation in MHC. We also observed pleiotropy between PSC genetic risk and smoking behaviour [R2 = 1.7%, FDR = 0.04]. Conclusions: Patients with a higher genetic burden of CD are more likely to develop fibrostenotic disease and undergo ileocaecal resection, whereas colonic CD shares genetic aetiology with PSC and UC that is largely driven by variation in MHC. These results further our understanding of specific IBD phenotypes.
|Number of pages||8|
|Journal||Journal of Crohn's and Colitis|
|Early online date||6 Nov 2020|
|Publication status||Published - 1 Jun 2021|
Bibliographical noteFunding Information:
Funding FH has received research grants from Dr Falk, Janssen-Cilag, Abbvie, and Takeda. RKW is supported by a Diagnostics Grant from the Dutch Digestive Foundation [D16-14]. NKHB has received unrestricted research grants from Dr Falk, TEVA Pharma BV, MLDS, and Takeda. EAMF is supported by an MLDS Career Development grant [CDG 14-04]. RKW has received unrestricted research grants from Takeda, Tramedico, and Ferring. EAMF has received an unrestricted research grant from Takeda.
© 2020 The Author(s). Published by Oxford University Press on behalf of European Crohn's and Colitis Organisation.