Restriction fragment length polymorphism analysis of the C1-inhibitor gene in hereditary C1-inhibitor deficiency

Hereditary and acquired angioedema: problems and progress: proceedings of the third C1 esterase inhibitor deficiency workshop and beyond

Hereditary angioedema (HAE), a rare but life-threatening condition, manifests as acute attacks of facial, laryngeal, genital, or peripheral swelling or abdominal pain secondary to intra-abdominal edema. Resulting from mutations affecting C1 esterase inhibitor (C1-INH), inhibitor of the first complement system component, attacks are not histamine-mediated and do not respond to antihistamines or corticosteroids. Low awareness and resemblance to other disorders often delay diagnosis; despite availability of C1-INH replacement in some countries, no approved, safe acute attack therapy exists in the United States. The biennial C1 Esterase Inhibitor Deficiency Workshops resulted from a European initiative for better knowledge and treatment of HAE and related diseases. This supplement contains work presented at the third workshop and expanded content toward a definitive picture of angioedema in the absence of allergy. Most notably, it includes cumulative genetic investigations; multinational laboratory diagnosis recommendations; current pathogenesis hypotheses; suggested prophylaxis and acute attack treatment, including home treatment; future treatment options; and analysis of patient subpopulations, including pediatric patients and patients whose angioedema worsened during pregnancy or hormone administration. Causes and management of acquired angioedema and a new type of angioedema with normal C1-INH are also discussed. Collaborative patient and physician efforts, crucial in rare diseases, are emphasized. This supplement seeks to raise awareness and aid diagnosis of HAE, optimize treatment for all patients, and provide a platform for further research in this rare, partially understood disorder.

A review of the reported defects in the human C1 esterase inhibitor gene producing hereditary angioedema including four new mutations

C1 esterase inhibitor (C1INH) is an important regulatory protein of the classical pathway of complement. Mutations in the gene for this protein cause the autosomal dominant disorder hereditary angioedema (HAE). Approximately 85% of patients with HAE have a Type I defect, characterized by a diminished level of antigenic and functional C1INH. Patients with Type II defects have sufficient protein, but one allele produces dysfunctional protein. We have sequenced the DNA from HAE patients and have discovered four previously unreported mutations. The first mutation is a splice site error at nucleotide 8721, which changes the 3' acceptor splice site AG to GG at the end of intron 5 at nucleotide 8721-8722. The second mutation is a single base insertion in exon 3 between nucleotides 2467 and 2468. The third mutation is a missense error present in the eighth exon of the C1INH; at nucleotide 16867 (amino acid 470), a T to A mutation transforms a Met to a Lys. The fourth mutation closely resembles the third mutation in that it is a missense error occurring in exon 8 in the distal hinge region; a T16827C substitution changes the Phe at amino acid 457 to Leu. This report compiles a list of 97 distinct defects in the C1INH gene that cause hereditary angioedema.

Urticaria and angioedema

Urticaria and angioedema are usually the clinical consequence of vasoactive mediators derived from mast cells in the skin or mucosal tissues. Efforts to classify mast cell-mediated causes of urticaria and angioedema have generally been frustrated by their diverse pathogenesis and clinical course. The term acute is typically used to describe fleeting lesions whose recurrence does not extend beyond 6 weeks. Chronic is the term used to describe lesions that persist for more than a few hours but usually less than a day, and recurrences extend for more than 6 weeks. These definitions do not take histology into account. Skin biopsies of fleeting lesions demonstrate a paucity of inflammatory cells, whereas more persistent lesions display a spectrum of perivascular cuffing by predominantly T cells and monocytes. The presence of leukocytoclastic vasculitis in persistent lesions indicates an underlying immune complex disease. Many of the physical urticarias have fleeting lesions that can be induced with the appropriate stimulus for years. This review article has emphasized the clinical course and histology of urticaria and angioedema lesions in an effort to provide a more complete understanding of the pathogenesis and appropriate treatment. Clearly, avoidance of an identifiable inciting stimulus is optimum management, although most patients have no etiology defined or the cause is not realistically avoidable. At present, treatment options for these patients rely on antihistamines to control the immediate consequence of mast cell degranulation. Corticosteroids are reserved for the treatment of patients whose urticaria or angioedema lesions persist, reflecting the increasing involvement of mononuclear cells in the disease process. For leukocytoclastic vasculitis, corticosteroids are indicated, and cytotoxic drugs may be required for adequate treatment. Future treatments of urticaria and angioedema will evolve based on elucidation of the relevant cells and soluble mediators and will include counterregulatory or antagonistic peptides and drugs. C1 esterase inhibitor deficiency is a relatively uncommon cause of angioedema but is important to understand because of its ability to clinically mimic mast cell-mediated angioedemas and its unique pathogenesis and treatment. HAE can be divided into two serologic subtypes that simply reflect the location of the defect in one of the codominantly expressed C1-INH genes on chromosome 11. AAE can be divided into two serologic subtypes. AAE type I is due to massive consumption of C1-INH, presumably by tumor-related immune complexes. AAE type II is due to an anti-C1-INH autoantibody.(ABSTRACT TRUNCATED AT 400 WORDS)