Distinct relationship between HLA-DR genes and intractability of ulcerative colitis

To explain the correlation between HLA class II genes and the intractability of ulcerative colitis (UC), DR genotyping and clinical analysis were performed for patients with UC.

HLA-DRB types and HLA-DR2 subtypes of 45 patients with UC in our hospital were determined using molecular genotyping in combination with sequence-specific oligonucleotide hybridization by polymerase chain reactions. The extent of involvement, clinical course, and treatment were studied to evaluate the intractability of UC.

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). In addition, DRw11 and DR2 increased significantly in the group including 18 cases with total colitis. In the 11 patients with total colectomy there were no cases with DRB1*1501, whereas 34 patients without operation included 12 genes of DRB1*1501 (p < 0.05). In addition, DRw11 increased significantly in the group with total colectomy compared to the group without operation (p < 0.05). When comparing between patients with and without intractability (defined based on the Japanese definition), DRB1*1502 and DRw11 were found more frequently in intractable UC patients (p < 0.01), whereas DRB1*1501 increased significantly in cases without intractability (p < 0.05).

DRB1*1502 or DRw11 have a probability of being closely related to the intractability of UC. In addition, patients with UC possessing DRB1*1501 have a lower probability of their cases leading to intractable UC. Thus, we believe there are unknown genes present that encode the intractability of UC.