Background: Inflammatory bowel disease is common in the West but rare in China. The genetic factor predisposing to the disease is unclear. Ulcerative colitis (UC) is found to be associated with HLA DR2 alleles in the West. Subgroups of UC patients have been further defined by the presence of anti-neutrophil cytoplasmic antibodies (ANCA).
Methods: We attempted to define the HLA class-II genes (DRbeta, DQalpha, DQbeta) and their relationship with ANCA in southern Chinese patients with UC. Patients were tested for class-II genes by restriction fragment length polymorphism and polymerase chain reactions. The indirect immunofluorescence test was used to detect ANCA in the sera. Ethnically matched normal controls were used for comparison.
Results: In ANCA-positive UC patients (n = 18) there was a strong association with HLA-DQalpha1c allele (P < 0.0001) when compared with controls (n = 104). This association was not found in ANCA-negative UC patients (n = 10) (P = 0.21).
Conclusions: In Chinese UC patients positive ANCA is associated with the HLA-DQalpha1c allele, which is not the case in Caucasian patients.