INBORN CLR DEFICIENCY WITH A MILD LUPUS-LIKE SYNDROME

We report the third kindred with Clr deficiency. The propositus presented at age 14.5 years with arthralgia and mild renal disease. Renal biopsy showed diffuse mesangioproliferative glomerulonephritis with focal C3 and IgG deposition. Antibodies to extractable nuclear antigen (Sm) and rheumatoid factor were present but there were no antibodies to native DNA. Large amounts of circulating immune complexes were present as determined by the Raji cell assay. Total hemolytic complement activity was < 1% and Cl hemolytic activity and Clr protein were absent. The defect was corrected by the addition of normal serum, C2-deficient serum, or highly purified Clr, but not by serum from a patient known to be deficient in Clr. Cls was 40% of normal. The levels of Clr protein and Cl hemolytic activity in family members suggested an autosomal recessive pattern of inheritance. This patient presents a more clear demonstration of the serologic and pathologic changes commonly seen in systemic lupus erythematosus than the previously reported Clr deficient patients. © 1979.