Association of the complement allele c4aq0 with primary Sjögren's syndrome in japanese patients

Abstract

We studied allotypes of the fourth component of complement (C4) and factor B in 76 patients with Sjögren's syndrome (SS) and in 63 normal subjects. C4A-null (C4AQ0) was found in 10 of 28 patients who had primary SS, compared with 1 of 63 control subjects (P less than 0.005). In contrast, no significant difference in the frequency of any C4 allotype was observed between patients with secondary SS and control subjects. An association of HLA-DRw53 with primary SS in Japanese patients has been reported. Since there is no linkage disequilibrium between DRw53 and C4AQ0, it is possible that at least 2 genes in the major histocompatibility complex may determine susceptibility to the development of primary SS in the Japanese population.