RECURRENT HEMATURIA - A NOVEL CLINICAL PRESENTATION OF HEREDITARY COMPLETE COMPLEMENT C4 DEFICIENCY

A 10-year-old boy suffered from recurrent attacks of fever, vomiting, and hematuria. During disease flares, circulating immune complexes wer e detected in the serum. Elevated levels of Bb, Ba, and C3a indicated complement activation through the alternative pathway. Complement C4 w as undetectable. C4 phenotyping by agarose gel electrophoresis showed complete C4 deficiency. Restriction fragment length polymorphism (RFLP ) studies showed a homozygous deletion of the C4B and 21-hydroxylase A genes. A mild mesangioproliferative glomerulonephritis with mesangial deposits of immunoglobulin (Ig) G, IgM, IgA, Clq, C3, properdin, and terminal complement complex was probably caused by immune complex depo sition and alternative complement pathway activation. Treatment with l ow-dose prednisolone substantially reduced the frequency of further ep isodes. (C) 1996 by the National Kidney Foundation, Inc.