Strong association between the major histocompatibility complex and systemic lupus erythematosus in southern Chinese.

The distribution of HLA-A, B, and DR alleles has been studied in 100 Chinese patients with systemic lupus erythematosus and in 100 healthy Chinese controls. Complement components factor B, C4A and C4B were studied in 72 patients and 61 controls. There was no significant difference between patients and controls in the distribution of HLA-A, HLA-B, factor B and C4B alleles, but there was a significant excess of HLA-DR2 and C4A null in the patients. An unusual variant of C4B was found in 6 patients and 1 control. The possible role of haplotypes is considered in interpreting these results and relating them to previous findings in Chinese.