ASSOCIATION OF HLA CLASS-II GENES AND ANTINEUTROPHIL CYTOPLASMIC ANTIBODIES IN CHINESE PATIENTS WITH INFLAMMATORY BOWEL-DISEASE

Background: Inflammatory bowel disease is common in the West but rare in China. The genetic factor predisposing to the disease is unclear. U lcerative colitis (UC) is found to be associated with KLA DR2 alleles in the West. Subgroups of UC patients have been further defined by the presence of anti-neutrophil cytoplasmic antibodies (ANCA). Methods: W e attempted to define the HLA class-II genes (DR beta, DQ alpha, DQ be ta) and their relationship with ANCA in southern Chinese patients with UC. Patients were tested for class-II genes by restriction fragment l ength polymorphism and polymerase chain reactions. The indirect immuno fluorescence test was used to detect ANCA in the sera. Ethnically marc hed normal controls were used for comparison. Results: In ANCA-positiv e UC patients (n = 18) there was a strong association with HLA-DQ alph a 1c allele (P < 0.0001) when compared with controls (n = 104). This a ssociation was not found in ANCA-negative UC patients (n = 10) (P = 0. 21). Conclusions: In Chinese UC patients positive ANCA is associated w ith the HLA-DQ alpha 1c allele, which is not the case in Caucasian pat ients.