Similarity of TCR repertoires between tissue samples within patients. (A) Comparison of TCR repertoire similarity by tissue comparison shown for each patient (blue, colon to colon; pink, upper to colon; green, upper to upper). (B) Within patients, the TCR repertoire between upper GI and colon tissue shows greater similarity in SR patients than in PR patients. Results are reported as the average Bhattacharrya coefficient of upper vs colon comparison per patient with upper and lower samples available (for PR, n = 8; for SR, n = 5; Mann-Whitney, P = .045). (C) SR tissue samples are more similar than PR. The best-fit model according to the Akaike information criterion included 2 fixed covariates (patient group and disparity in histology) and fit the data significantly better than a null model containing no fixed covariates (P = .0323).