Evidence of subclinical gut inflammation, mucosal dysregulation or MRI evidence indicative of sacroiliitis in FDRs
| FDR | ASCA IgA | ASCA IgG | CBir1 | fCal (mcg/g) | MRI findings | HLA-B27 status |
| Subject 2 | Negative | Negative | Negative | 109.4 (ULN) | Minimal bone marrow oedema of right sacroiliac joint present solely on a single slice; not considered positive | Positive |
| Subject 4 | Negative | Positive | Negative | <15.6 (Negative) | Not present | Negative |
| Subject 6 | Negative | Negative | Negative | <15.6 (Negative) | Bilateral sacroiliitis with inflammatory bone marrow oedema | Negative |
| Subject 8 | Positive | Positive | Positive | 157.3 (ULN) | Not present | Negative |
| Subject 11 | Negative | Negative | Positive | <15.6 (Negative) | Not present | Positive |
| Subject 12 | Negative | Negative | Negative | 76.6 (Negative) | Mild active right sacroiliitis | Positive |
| Subject 15 | Negative | Negative | Positive | <15.6 (Negative) | Not present | Negative |
| Subject 16 | Negative | Negative | Negative | No sample available | Small area of sclerosis of left sacroiliac joint | Negative |
| Subject 18 | Negative | Negative | Positive | 81 (Negative) | Not present | Negative |
| Subject 20 | Negative | Negative | Positive | 28 (Negative) | Not present | Negative |
| Subject 27 | Negative | Negative | Positive | 69.4 (Negative) | Active sacroiliitis left inferior sacroiliac joint, subtle changes right sacroiliac joint suggest chronic changes related to sacroiliitis but no active inflammation | Positive |
| Subject 28 | Negative | Negative | Negative | 137 (ULN) | Advanced bilateral sacroiliitis | Positive |
ASCA, anti-Saccharomyces cerevisiae antibodies; CBir1, antiflagellin antibodies; fCal, faecal calprotectin; FDR, first-degree relative; HLA-B27, human leucocyte antigen B27; Ig, immunoglobulin; ULN, upper limit of normal.