HLA-linked complement polymorphisms (C2, BF) in psoriasis

Summary Starting from the known association between psoriasis and several HLA antigens and from the fact that the HLA chromosomal region contains the structural genes for at least three complement components, the authors have looked for an association between psoriasis and allotypes of C2 and BF. C2 and BF polymorphism were examined in 230 psoriatic patients. Two rare complement genes were found to be significantly increased when compared with controls: the frequency of the C2 ^*2 gene was 0.061 among patients and 0.035 among controls (P<0.05); for BF ^*SO7, the frequencies were 0.0304 in patients and 0.0092 in controls (P<0.0005). The BF ^*F gene frequency, however, was significantly decreased among patients: 0.1196 vs. 0.1743 (P<0.01). The relative risks were 1.79 for the C22, 3.44 for the BF SO7, and 0.6 for the BFF gene product. From previous studies, it is known that these three complement alleles (C2 ^*2, BF^* SO7, BF ^*F) are in linkage disequilibrium with HLA alleles that have also been found increased or decreased, respectively, in psoriasis.Presented in part at the 4th International Congress of Immunology, Paris, July 21–26, 1980