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C1-inhibitor deficiency is a rare disease which incorporates acute self-limiting intermittent swelling of the subcutaneous tissue and mucous membranes. Attacks most frequently affect the face and/or the upper airway. Isolated angioedema of the small bowel is an uncommon manifestation and often accompanied by diagnostic delay. In the present case, abdominal pain turned out to be the first and only utterance of an acquired C1-inhibitor deficiency, secondary to a splenic marginal zone lymphoma. Imaging showed wall thickening of the small intestine, ascites and splenomegaly. The abdominal pain and intestinal wall thickening with surrounding ascites on imaging spontaneously resolved each episode within 2-3 days. Gastrointestinal manifestations of angioedema may mimic an acute abdomen, and subsequently one-third of these patients undergo unnecessary surgery prior to a definite diagnosis. This emphasises the importance of considering the diagnosis in case of an 'extraordinary colic'., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2022. No commercial re-use. See rights and permissions. Published by BMJ.)

An acquired form of angioedema that is clinically similar but scarcer than the hereditary form may be caused, even more rarely, by the presence of an underlying autoimmune disease. We report a previously healthy 16-year-old girl with an acquired angioedema as a rare and initial presentation of systemic lupus erythematosus. The patient had no previous angioedema attack and no family history. She did not have any chronic diseases and did not use any medicine regularly. The patient was diagnosed with systemic lupus erythematosus with the presence of polyarthralgia, angioedema, leucopenia, and positivity of immunologic criteria. Her edema resolved with high-dose methylprednisolone and hydroxychloroquine slowly. In conclusion, new-onset angioedema in adolescent girls should be investigated to evaluate autoimmunity and the possibility of systemic lupus erythematosus. The related literature on acquired angioedema associated with systemic lupus erythematosus is also reviewed.

C1 inhibitor disorders are a group of rare conditions in which the C1 inhibitor is deficient or defective. We present the clinical characteristics of 8 patients and a review of the literature. These are characterized by recurrent episodes of angioedema, which most often affect the skin or mucosal tissues of the upper respiratory and gastrointestinal tract. Laryngeal involvement may cause fatal asphyxiation. These disorders may be divided into two broad categories: hereditary angioedema (HAE) and acquired C1 inhibitor disorders. Indications for screening for HAE include: recurrent angioedema, episodic abdominal pain, laryngeal, a family background of angioedema, and a low C4 level. Acquired C1 inhibitor disorders are similar, but lack a family background. Treatment is divided into short and long-term prophylaxis with androgens, antifibrinolytics and C1 inhibitor replacement. First line therapy of acute attacks is C1 inhibitor.

Hereditary and acquired deficiencies of the C1 inhibitor result in a single prominent symptom, namely angioedema. Angioedema may involve the skin, the gastrointestinal tract or the upper airway. Genetically determined defects in C1INH cause hereditary angioedema. The defect may be acquired as the result of an auto-antibody to C1INH or be due to the generation of anti-idiotypic antibody to monoclonal immunoglobulins as occurs in various B cell lymphoproliferative diseases. Androgens provide prophylaxis against attacks of angioedema. There is no widely approved treatment for acute attacks of angioedema although several promising drugs are now in the final stages of clinical trials.

Hereditary angioedema (HAE) is an autosomal dominant disease characterized by recurrent episodes of potentially life-threatening angioedema. Attacks of angioedema in HAE patients typically last 3 or more days, begin during childhood, and continue to occur throughout life. Tragically, patients with HAE continue to die as a direct consequence of the disease. Minimizing the morbidity and mortality associated with HAE requires both effective treatment of acute attacks as well as strategies to prevent HAE attacks. While there is currently no effective therapy available in the United States for the treatment of acute attacks of HAE, several molecules have demonstrated impressive efficacy in this setting, and it is likely that one or more of these new drugs will become available in the United States soon. This article will review both the current and the future therapeutic options for the treatment of HAE.

Hereditary angioedema (HAE), characterized by recurrent episodes of angioedema involving the skin, or the mucosa of the upper respiratory or the gastrointestinal tracts, results from heterozygosity for deficiency of the serine proteinase inhibitor (serpin), C1 inhibitor (C1INH). The primary biological role of C1INH is to regulate activation of the complement system, the contact system, and the intrinsic coagulation system. During attacks of angioedema, together with decreasing levels of C1INH, the complement and contact systems are activated: C2 and C4 levels fall and high molecular weight kininogen is cleaved. Although previous data suggested that symptoms in HAE might be mediated via complement system activation, a combination of recent clinical data, in vitro studies, and analysis of C1INH-deficient mice all indicate that the major mediator of angioedema is bradykinin: (1) a vascular permeability enhancing factor can be generated in vitro in C1INH-depleted, C2-deficient plasma, but not from C1INH-depleted, contact system-deficient plasma; this factor was identified by sequence analysis as bradykinin; (2) bradykinin can be detected in the plasma of HAE patients during attacks of angioedema; (3) in several members of one family, expression of a C1INH variant that inhibits contact system proteases but has defective inhibition of C1r and C1s does not result in HAE; (4) C1INH-deficient (C1INH-/-) mice have a defect in vascular permeability that is suppressed by treatment with specific plasma kallikrein inhibitors and by bradykinin type 2 receptor (Bk2R) antagonists, and is eliminated in C1INH-/-, Bk2R-/- double-deficient mice.

Glycosylation, an important post-translation modification, could alter biological activity or influence the clearance rates of glycoproteins. We report here the first example of a heterozygous protein deficiency leading to metabolic alteration of N-glycan structures in residual secreted protein. Analysis of C1 esterase inhibitor (C1INH) glycans from normal individuals and patients with hereditary deficiency of C1INH demonstrated identical O-glycan structures but the N-glycans of patients with a heterozygous genetic deficiency were small, highly charged and lacked sialidase releasable N-acetylneuraminic acid. Structural studies indicate that the charge character of these aberrant N-glycan structures may result from the presence of mannose-6-phosphate residues. These residues might facilitate secretion of C1INH through an alternate lysosomal pathway, possibly serving as a compensatory mechanism to enhance plasma levels of C1INH in these deficient patients.

A 60-year-old woman who was diagnosed with hereditary angioedema (HAE) developed nephrotic syndrome, with end-stage renal disease (ESRD) occurring about 2.5 years later. During her slide toward ESRD, she experienced three severe episodes of angioedema that each resulted in significant fluid retention. Though the therapeutic administration of C1-inhibitor concentrate was effective in controlling her angioedema, seemed ineffective in preventing her from developing ESRD requiring hemodialysis treatment. We theorized that the patient's low colloid osmolality and glomerular perfusion were important facilitators of her attacks of angioedema.

This report describes a patient with hereditary angioedema (HAE) in whom complement C4 values were consistently normal. There was a family history of HAE, for which the patient had previously been screened, but in view of her normal C4 values she was deemed unaffected. However, at 10 years of age she presented with an eight month history of episodes of swelling affecting her hands and recurrent episodes of abdominal pain over the previous few months. In view of the recent clinical history of swellings and the family history of HAE, C4 and C1 inhibitor (C1inh) were measured. The C4 concentration was found to be within the normal range but the C1inh value was low (0.07 g/litre; normal range, 0.18-0.37). The patient was started on tranexamic acid and at an outpatient review three months later her episodes of swelling were occurring less often and were less severe. Although recent papers have suggested that the diagnosis of HAE can be excluded if complement C4 concentrations are normal, this case highlights the fact that C4 concentrations can be normal in this condition, and it is recommended that both C4 and C1inh concentrations should be measured to exclude HAE.

Aetiology of angioedema (and therefore the scheme of its treatment) can be different. Angioedema may be subdivided into four categories: hereditary and acquired angioedemas, allergies and vasculitis. To establish the reason of the hereditary and acquired form of angioedema analyses of functional activity of complement components, quantities and activity of C1 inhibitor, presence (or absence) autoantibodies to C1 inhibitor allow. Sorption of the puried enzymes of activated subcomponent C1s or plasmin on micropanels allows to connect specifically in cells of plate C1 inhibitor from serum and with the help conjugate of antibodies against C1 inhibitor with a horse-radish peroxidase to determine quantity of connected functionally active C1 inhibitor. Addition of this test-system ELISA system for determination of quantitative contents of C1 inhibitor in serum, and also systems for definition IgG, IgA and IgM autoantibodies against C1 inhibitor finishes creation of a necessary set of methods of differential diagnostics.

Angioedemas are a rare but significant event in simple oral surgery because they can cause an acute life-threatening laryngeal edema. We report a case of a tooth extraction in a patient with hereditary angioedema, for which the C1-inhibitor (C1-INH) concentration administered effectively controlled edema during and after extraction. We also review case reports of oral surgery management in patients with hereditary and acquired angioedemas. In 2 of 36 cases, laryngeal edema occurred after teeth extraction. One was considered to be a type 2 acquired angioedema, which tolerates replacement therapy with fresh frozen plasma. The other case was managed only with danazol, and it was suggested that this was on occasion insufficient. Safety of oral surgery on patients with angioedema depends on the type of angioedema and the availability of C1-INH concentration. An exact diagnosis of the type of angioedema is needed to know the effect of replacement therapy with C1-INH.

Background: Recurrent angioedema is the hallmark of various inherited or acquired angioedema diseases. Hereditary angioedema, or HAE, due to C1 inhibitor, or C1NH, deficiency has considerable implications for dental health care providers because dental surgery may trigger distressing and even life-threatening episodes., Case Description: The authors reviewed the literature, focusing on the pathogenesis, clinical signs and treatment of HAE. They also provided case reports of four patients who died from laryngeal edema induced by tooth extraction. In patients with HAE, dental surgery--including tooth extraction--may be followed by self-limiting edema episodes, including lip swelling, facial swelling, tongue edema and laryngeal edema with upper airway obstruction. Preoperative prophylaxis has been performed with attenuated androgens, fresh frozen plasma, C1NH concentrate and antifibrinolytics. The four patients described underwent tooth extraction, which, after a symptom-free latency of four to 30 hours, provoked laryngeal edema. Three of the patients died of asphyxiation the night after surgery, and the fourth died on the second night. In three of the patients, laryngeal edema had not occurred previously., Clinical Implications: Before undergoing dental surgery, patients with a history of recurrent angioedema should be evaluated for C1NH deficiency. If it is present, they are at risk of developing life-threatening laryngeal edema.

Angioedema due to acquired C1-inhibitor (C1-INH) deficiency (also referred to as "acquired angioedema") is a rare, life-threatening disease with poorly defined etiology, therapy, and prognosis. To define the profile of acquired C1-INH deficiency and to facilitate the clinical approach to these patients, we report on 23 patients with acquired C1-INH deficiency followed for up to 24 years (median, 8 yr), and review the literature. We measured C1-INH activity with chromogenic assay and detected autoantibodies to C1-INH by enzyme-linked immunosorbent assay (ELISA). Median age at onset of angioedema was 57 years (range, 39-75 yr). All patients had C1-INH function and C4 antigen below 50% of normal. C1q was reduced in 17 patients. Autoantibodies to C1-INH were present in 17 patients. Long-term prophylaxis of attacks with danazol was effective in 2 of 6 patients, and with tranexamic acid, in 12 of 13 patients. Therapy with C1-INH plasma concentrate was necessary in 12 patients: 9 had rapid positive response and 3 became progressively resistant. Associated diseases at the last follow-up were non-Hodgkin lymphomas (3 patients), chronic lymphocytic leukemia (1 patient), breast cancer (1 patient), monoclonal gammopathies of uncertain significance (13 patients). In 4 patients no pathologic condition could be demonstrated. Compared with the general population, patients with acquired C1-INH deficiency present higher risk for B-cell malignancies, but not for progression of monoclonal gammopathies of uncertain significance to malignancy. Antifibrinolytic agents are more effective than attenuated androgens in long-term prophylaxis. Patients with acquired C1-INH deficiency may be resistant to replacement therapy with C1-INH plasma concentrate.

Background: Hereditary angio-oedema is a rare, life-threatening, autosomal dominant condition caused by deficiency (type 1) or dysfunction (type 2) of complement C1 inhibitor. Serological assays to measure C1 inhibitor concentration and function are widely available. However, expert interpretation may not be., Objective: To review all cases within three NHS Trusts with a putative diagnosis of hereditary angio-oedema., Method: Review of laboratory results and clinical notes of 44 cases of presumed hereditary angio-oedema., Results: Audit revealed that 11 of 42 (26%) cases had been incorrectly considered to have a diagnosis of hereditary angio-oedema. Two of 44 had insufficient data to assess. All 11 had low functional C1 inhibitor recorded at presentation., Results: available in these 11 cases at the time of diagnosis showed a normal or borderline C4 level (>or= 50% of mean normal, in contrast to hereditary angio-oedema, where C4 was less than 40% of mean normal) indicating that the low C1 inhibitor levels were a result of sample decay. Cases incorrectly diagnosed were predominantly female and had a mean age at presentation of 40 years (compared with 22 years for type 1 hereditary angio-oedema). Six of the 11 cases were offered C1 inhibitor concentrate (pooled plasma product) as treatment., Conclusion: We recommend that all suspected cases of hereditary angio-oedema are reviewed, that specialist advice is sought before making the diagnosis and that the diagnosis is only made after initial abnormal serology is confirmed on a second sample.

Background: Oral contraceptives can precipitate attacks of hereditary angioedema (ANE) or induce acquired forms., Objective: We studied 5 patients who had an ANE which had begun under oral contraception and disappeared after stopping the pill., Methods: We explored the clinical and biological characteristics of these patients., Results: The symptoms developed during the first year or later after starting contraception; the patients reported relapsing swelling of the lips, hands, larynx and abdomen. All women had normal serum C4 and C1 inhibitor (C1Inh) antigen levels, but a lowered C1Inh activity, with a marked protein cleavage on the immunoblot. The suppression of the pill was associated with the regression of the edema and normalization of C1Inh function., Conclusion: The mechanism of these ANE is unknown. The could be due to a modulation of C1Inh expression upon androgens or an imbalance between coagulation proteins favoring C1Inh cleavage by its target proteases., (Copyright 2003 S. Karger AG, Basel)

A female patient developed discoid lupus erythematosus 6 years after the onset of hereditary angioneurotic oedema. Treatment with danazol for 18 months cleared both conditions and was well tolerated.

Although hereditary angioedema accounts for only a small fraction of all cases of angioedema, it is the most common genetically linked clinical disorder caused by the deficiency of a protein associated with complement activation. Attacks may be complicated by incapacitating cutaneous swelling, life-threatening upper airway impediment, and severe gastrointestinal colic. Recent physicochemical and genetic studies have contributed significantly to our understanding of the structure of the inhibitor protein. Measurement of serum C4 titer is an efficacious screening test. Normal levels during symptomatic periods rule out the diagnosis, whereas decreased levels warrant determination of C1 esterase inhibitor titer by immunoassay or functional assay. The functional assay is necessary to ascertain the genetic variant form. The importance of making the correct diagnosis cannot be overemphasized. It can avert potentially fatal consequences, such as upper airway obstruction and unnecessary abdominal surgery. The application of short-term preventive measures can avoid complications associated with trauma. Finally, abatement or elimination of symptoms in patients with incessant and disabling attacks can be attained by long-term therapy with currently available attenuated androgens.

We measured beta-endorphin (BE) and beta-lipotropin (BLPH) plasma concentrations (by means of an HPLC-RIA coupled method) during attacks as well as during symptom-free periods in a group of 28 patients with immunochemical (21) or functional (7) Cl inhibitor deficiency. Thirteen patients suffering from chronic urticaria served as controls. Three orders of considerations prompted us to initiate the present study: the clinical relationship between stress and the onset of acute episodes, the possible effects of repeated stressful situations, as are the attacks themselves, on the patients' neuroendocrine system and the well-known existence of close links between the immune system and endogenous opioids. The results show that plasma BE (and, to a lesser extent, BLPH) is dramatically increased during the attacks. In symptom-free periods many patients show very high BE concentrations, often in the presence of slightly elevated concentrations of BLPH and of ACTH. These observations suggest that patients with hereditary angioneurotic edema show a modified pro-opiomelanocortin-synthesizing cell activity that can result in a massive release of BE from the readily disposable pool present in the pituitary and/or an increase in the turnover of the peptide as evaluated by the BLPH/BE ratio.

Stanozolol, an inexpensive anabolic steroid with a 30:1 anabolic:androgenic ratio, was administered to 12 male and 15 female patients with biochemically proven hereditary angioedema over a 2-yr period to obtain a systematic assessment of the relationship between drug dosage and clinical response, incidence of side effects, and amelioration of complement abnormalities. All 27 patients attained the minimal effective dose, ranging from 0.5 to 2 mg daily, which controlled the frequency and intensity of symptoms with minimal side effects. At daily maintenance doses of 2, 1, and 0.5 mg the frequencies of attacks per weeks of therapy were 1/14.6, 1/7.2, and 1/8.2 wk, respectively. Side effects with maintenance therapy included menstrual abnormalities and virilization in four females and elevation of serum creatinine phosphokinase (CPK) in five males. In six patients on maintenance doses of stanozolol, serum levels of testosterone, free thyroxin (T4), and thyroxin binding globulin (TBG) (four males), and of estradiol, progesterone, T4, and TBG (two females) were normal. Slightly low serum levels of progesterone and TBG were found in two females who had normal menstrual cycles. Statistically significant elevations above pretherapy levels of serum inhibitor to the activated first component of complement function and C4 protein and function occurred when patients were on maintenance therapy, but these measurements remained below the lower limit of normal range. Higher doses of stanozolol (4 mg/day), which caused greater immunochemical responses, were unnecessary for control of clinical disease and were unjustified for chronic therapy because of more frequent side effects.

Treatment with 17 alpha-methyltestosterone and with some synthetic androgens prevents attacks of hereditary angioedema (HAE). However, the potential hepatotoxicity of 17 alpha-alkylated androgens raises the problem of long-term prophylactic use of these agents. Therefore we compared the efficacy in preventing HAE attacks of 17 alpha-alkylated steroids (danazol and stanozolol) with non-17 alpha-alkylated derivatives (quinbolone, nandrolone decanoate and mesterolone). As the latter group proved ineffective, it seems that a drug's efficacy in preventing HAE attacks is connected to its 17 alpha-alkylation. Moreover, our long-term observations with the minimum effective dose of danazol seem to indicate the absence of important collateral effects.

Danazol, an androgen derivative, was evaluated for its effectiveness in preventing attacks of hereditary angioedema in a double-blind study with nine patients. Of 47 placebo courses, 44 ended with attacks, but during 46 danazol courses only one attack occurred. Side effects were minimal, and virilization was not observed in the women studied. C1 esterase inhibitor levels increased three to four times, and levels of the fourth component of complement (C4) increased 15 times. These changes began during the first day of therapy and were maximal by one to two weeks. After therapy was stopped, C1 esterase inhibitor and C4 levels rapidly decreased. Danazol effectively prevents attacks in hereditary angioedema and acts to correct the underlying biochemical abnormality.

It is often impossible to make a clinical distinction between acquired and hereditary acute angioneurotic oedema. Investigation of the complement system is indispensable for this diagnosis to be established. The value of total complement and C4 and C2 are lowered in the sera in the hereditary form (44 cases) and normal in the acquired type (68 cases). The use of tests for the activation of C1 esterase "in vitro" is useful to distinguish these two types of oedema as has been demonstrated by the formal measurement of C1 esterase inhibitor.

A case of hereditary angio-oedema is described together with the family history and manifestations in the father of the patient. The problems encountered in his management are discussed, including tracheostomy and genetic counselling.

Simple rapid procedures for identification and analysis of dysfunctional C1-inhibitor proteins mutated at the reactive-centre P1 residue have been developed and used to define structurally a C1-inhibitor protein, C1-inhibitor(At), isolated from an individual with hereditary angio-oedema. The observed mutation, Arg444----His, is compatible with a single base change in the codon used for Arg444 in the native protein.

Three families with hereditary angioneurotic oedema (HANE) are described. Serum CI-INH and C4 immunochemical determinations were performed on 23 members of the families: in 6 persons low CI-INH and C4 levels were found with typical symptoms of HANE, and in one asymptomatic subject. Normal ranges of both proteins for adults, children and newborns are given for comparative purposes. The importance of the early diagnosis and treatment is emphasized.

Two male patients with hypogonadism and four female patients who received an anti-androgen as contraceptive (cyproteronacetate) and who had recurrent angioedema are described. In one male patient, augmentation of the plasma androgen level resulted in disappearance of symptoms. In the four female patients, recurrent angioedema and urticaria developed after initiation of the anti-androgen treatment. Cessation of cyproteronacetate and a change to another contraceptive resulted in complete resolution of the previously frequent angioedematous attacks. The women are still symptom free after more than 60 patient's months. These cases suggest that an androgen deficit due to either hypogonadism or to anti-androgen treatment may be another cause of angioedema. One of the two male patients was untreated and presented with 40% normal value of C1-INH. Androgen therapy normalized C1-INH concentration in this male patient. Functional C1-INH in the same patient, studied before and after the beginning of androgen therapy, clearly increased when assessed by inhibition of amidolytic activity of C1-esterase. The other male patient with hypogonadism had already been under androgen treatment for 4 years and had C1-INH levels in the normal range. In the female patients, complement profiles were normal before and after cessation of anti-androgen contraception; however, the C1-INH plasma levels were higher after cessation of anti-androgen anticonception. These results indicate an effect of androgen deficit on the level of C1-INH in circulating plasma but do not prove a role of C1-INH in angioedema associated with diminished androgen plasma levels.

Abdominal manifestations are almost constantly present (85% of cases) in the current form of hereditary Quincke's disease. In some cases, these abdominal manifestations occur even when cutaneomucosal edema is not present which leads to unwarranted often repeated and sometimes dangerous surgery. Apart from a story of heredity diagnosis of such troubles is possible, provided the total complement has been assayed to note its sharp fall. It can be subsequently explained by a functional defect of the C1 esterase inhibitor or alpha2-neuraminoglycoprotein.