title: Behavior in vivo of normal and dysfunctional C1 inhibitor in normal subjects and patients with hereditary angioneurotic edema.
abstract: The metabolism of normal C1 inhibitor and two dysfunctional C1 inhibitors (Ta and WeI) was studied in 10 normal subjects and 8 patients with hereditary angioneurotic edema (HANE), 4 with low antigen concentration (type 1) and 4 with dysfunctional protein (type 2). The fractional catabolic rate of the normal C1 inhibitor in normal subjects was 0.025 of the plasma pool/hour, whereas in HANE subjects it was significantly elevated at 0.035 of the plasma pool/hour. The synthesis of normal C1 inhibitor was decreased in patients with type 1 HANE (0.087 mg/ kg per h compared with 0.218 mg/kg per h). The fractional catabolic rate of dysfunctional protein WeI was similar to normal and showed a slightly accelerated catabolism in patients with HANE, whereas the dysfunctional protein Ta had a strikingly decreased fractional catabolic rate in normals and subjects with HANE. The present study is compatible with reduced C1 inhibitor synthesis in patients with type 1 HANE consistent with a single functional C1 inhibitor gene. The lower than anticipated levels of C1 inhibitor in HANE type 1 appears to result from (a) the single functional gene and (b) increased catabolism of the protein, perhaps related to activation of C1 or other proteases.
mesh_terms: D000293:Adolescent; D000328:Adult; D000799:Angioedema / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D003174:Complement C1 Inactivator Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged
chemical_list: D003174:Complement C1 Inactivator Proteins