Familial deficiency of two subunits of the first component of complement. C1r and C1s associated with a lupus erythematosus-like disease.
Complete absence of C1r and almost complete absence of C1s were found in 4 of 8 living siblings. Two of the 4 suffer from a syndrome that combines discoid lupus erythematosus and nondeforming rheumatoid-like arthritis; one of the siblings has mild nephritis. The other 2 C1 deficient family members are clinically well. Evidence from this and other families suggests that deficiency of C1 components or C4 is associated with higher risk of developing a lupus-like disease than is deficiency of C2.
D000293:Adolescent; D000328:Adult; D001172:Arthritis, Rheumatoid / Q000235:genetics / Q000276:immunology*; D002648:Child; D003172:Complement C1 / Q000172:deficiency*; D003174:Complement C1 Inactivator Proteins / Q000032:analysis; D005260:Female; D006680:HLA Antigens / Q000032:analysis; D006801:Humans; D007223:Infant; D008179:Lupus Erythematosus, Discoid / Q000235:genetics / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D010375:Pedigree
D003172:Complement C1; D003174:Complement C1 Inactivator Proteins; D006680:HLA Antigens