Homozygous deficiency of C4 in a child with a lupus erythematosus syndrome.

A complete, selective lack of C4 was found in a girl who at 2 years of age presented with an atypical rash and low titres of antinuclear antibodies (less than 1/25). Rheumatoid factors were also found. The deficiency has been followed for 5 years. Tests for Chido and Rodgers antigens on the erythrocytes were negative. A possible proneness to bacterial infections has been noted with recurrent otitis media and purulent parotitis. At the age of 5, the patient developed polyarthritis of large joints and signs of glomerulonephritis. These symptoms responded well to high-dose steroid treatment. At present, there are initial signs of sclerodactylia and some persistent exanthema and parotic swelling. IgM levels were remarkably high with 19 S IgM at about 7 g/l and 7 S IgM at about 1.5 g/l. In the large kindred studied, lower immunochemical and functional C4 values were found in carriers of the genetical defect than in the rest of the family members. The C4 deficiency gene(s) segregated with HLA A2, Cw3, B40, BfS on the paternal, and with Aw30,-, B18, BfF1 on the maternal side of the family.