An 11-year-old white female with focal glomerulonephritis was found to have a complete absence of functional C1 esterase inhibitor. Serum levels of C1 esterase inhibitor measured by immunochemical analysis, however, were only slightly reduced. Prolonged depression of serum C2 and C4, evidence of circulating and active C1 esterase, and normal levels of serum C3 and alternative pathway proteins were also present. Several family members had similar immunochemical findings. Neither the patient nor her family had clinical signs of hereditary angioneurotic edema (HANE) despite the continued C consumption which has persisted for at least 24 months. These findings suggest that mechanisms other than the generation of a vasoactive peptide from C2 might be responsible for the clinical features of HANE.
Further, evidence from immunofluorescence studies of the deposition of IgG and C3 on the kidney of this patient suggests the participation of an immune complex and terminal C activity in the genesis of the glomerulonephritis.