In UC patients, DQB1*03:02 was predictive of colonic extension whereas DRB1*13 and DQB1*03:01 were associated limited disease localization (left-sided colitis and proctitis).
The allele frequency of HLA-DRB1*08 was significantly higher in patients whose disease extended beyond the rectum (left-sided and extensive UC) than in those with proctitis [odds ratio (OR)=2.20, Pc=0.043).
The gene frequency of DRB1*1502 in 18 patients with total colitis (0.444) was significantly higher than the group with left-sided colitis and proctitis (0.148; p < 0.05).