Gene Mutations Linked to Hereditary Angioedema in Solitary Angioedema Patients With Normal C1 Inhibitor

BACKGROUND

Chronic recurrent angioedema without wheals (CRA) with normal C1 inhibitor (C1-INH) that is unresponsive to antihistamines may involve patients with recurrent angioedema of unknown cause (ie, so-called non-histaminergic idiopathic angioedema) as well as patients with hereditary angioedema with normal C1-INH (HAEnCI) when HAEnCI occurs in only one family member.

OBJECTIVE

To identify patients with one of type of HAEnCI in a group of patients with CRA with normal C1-INH that was unresponsive to antihistamines.

METHODS

A total of 132 patients with CRA and normal C1-INH that was unresponsive to antihistamines underwent mutational and clinical analysis. The presence of hereditary angioedema-specific mutations in Factor XII, plasminogen, ANGPT1, KNG1, MYOF, and HS3ST6 genes was tested by Sanger sequencing. When an HAEnCI-causing mutation was identified, available asymptomatic relatives were genetically tested.

RESULTS

In 116 of 132 solitary patients with CRA (87.9%), none of the six HAEnCI-linked mutations could be found. Ten patients (7.6%) had the Factor XII mutation c.983C>A (p.T328K) and six (4.5%) the plasminogen mutation c.988A>G (p.K330E). Other mutations linked to HAEnCI were not found in this patient series. In the 16 families with HAEnCI, 11 asymptomatic carriers of one of the HAEnCI-linked mutations were identified.

CONCLUSIONS

A search for HAEnCI-linked mutations in patients with solitary CRA may lead to the detection of patients and families with HAEnCI. This is important because family members can be identified who are at risk for developing potentially life-threatening angioedema, although they were previously asymptomatic. Without genetic investigation, the risk for an HAEnCI would have remained undetected in these patients and asymptomatic relatives.

Mapping O-glycosylation Sites Using OpeRATOR and LC-MS

O-glycosylation is a difficult posttranslational modification to analyze. O-glycans are labile and often cluster making their analysis by LC-MS very challenging. OpeRATOR is an O-glycan specific protease that cleaves the protein backbone N-terminally of glycosylated serine and threonine residues. This enables the generation of glycopeptides of suitable size for mapping O-glycosylation sites in detail by bottom-up LC-MS analysis. In this chapter we demonstrate a simple workflow for in-depth analysis of O-glycosylation sites on heavily glycosylated proteins using OpeRATOR digestion and HILIC-MS/MS analysis.

Treatment of COVID-19 With Conestat Alfa, a Regulator of the Complement, Contact Activation and Kallikrein-Kinin System

A dysregulated immune response with hyperinflammation is observed in patients with severe coronavirus disease 2019 (COVID-19). The aim of the present study was to assess the safety and potential benefits of human recombinant C1 esterase inhibitor (conestat alfa), a complement, contact activation and kallikrein-kinin system regulator, in severe COVID-19. Patients with evidence of progressive disease after 24 h including an oxygen saturation <93% at rest in ambient air were included at the University Hospital Basel, Switzerland in April 2020. Conestat alfa was administered by intravenous injections of 8400 IU followed by 3 additional doses of 4200 IU in 12-h intervals. Five patients (age range, 53-85 years; one woman) with severe COVID-19 pneumonia (11-39% lung involvement on computed tomography scan of the chest) were treated a median of 1 day (range 1-7 days) after admission. Treatment was well-tolerated. Immediate defervescence occurred, and inflammatory markers and oxygen supplementation decreased or stabilized in 4 patients (e.g., median C-reactive protein 203 (range 31-235) mg/L before vs. 32 (12-72) mg/L on day 5). Only one patient required mechanical ventilation. All patients recovered. C1INH concentrations were elevated before conestat alfa treatment. Levels of complement activation products declined after treatment. Viral loads in nasopharyngeal swabs declined in 4 patients. In this uncontrolled case series, targeting multiple inflammatory cascades by conestat alfa was safe and associated with clinical improvements in the majority of severe COVID-19 patients. Controlled clinical trials are needed to assess its safety and efficacy in preventing disease progression.

Brazilian Guidelines for Hereditary Angioedema Management - 2017 Update Part 1: Definition, Classification and Diagnosis

Hereditary angioedema is an autosomal dominant disease characterized by recurrent angioedema attacks with the involvement of multiple organs. The disease is unknown to many health professionals and is therefore underdiagnosed. Patients who are not adequately diagnosed and treated have an estimated mortality rate ranging from 25% to 40% due to asphyxiation by laryngeal angioedema. Intestinal angioedema is another important and incapacitating presentation that may be the main or only manifestation during an attack. In this article, a group of experts from the "Associação Brasileira de Alergia e Imunologia (ASBAI)" and the "Grupo de Estudos Brasileiro em Angioedema Hereditário (GEBRAEH)" has updated the Brazilian guidelines for the diagnosis and treatment of hereditary angioedema.

Screening for hereditary angioedema (HAE) at 13 emergency centers in Osaka, Japan: A prospective observational study

Hereditary angioedema (HAE) with deficiency of C1 inhibitor (C1-INH) is an autosomal-dominant disease characterized by recurrent episodes of potentially life-threatening angioedema. The objective is to study the incidence of HAE among patients who visit the emergency department.This was a 3-year prospective observational screening study involving 13 urban tertiary emergency centers in Osaka prefecture, Japan. Patients were included if they met the following criteria: unexplained edema of the body, upper airway obstruction accompanied by edema, anaphylaxis, acute abdomen with intestinal edema (including ileus and acute pancreatitis), or asthma attack. C1-INH activity and C4 level were measured at the time of emergency department admission during the period between July 2011 and June 2014.This study comprised 66 patients with a median age of 54.0 (IQR: 37.5-68.3) years. Three patients were newly diagnosed as having HAE, and 1 patient had already been diagnosed as having HAE. C1-INH activity levels of the patients with HAE were below the detection limit (<25%), whereas those of non-HAE patients (n = 62) were 106% (IQR: 85.5%-127.0%) (normal range, 70%-130%). The median level of C4 was significantly lower in the patients with HAE compared with those without HAE (1.2 [IQR: 1-3] mg/dL vs 22 [IQR: 16.5-29.5] mg/dL, P < 0.01) (normal range, 17-45 mg/dL).Three patients with undiagnosed HAE were diagnosed as having HAE in the emergency department during the 3-year period. If patients have signs and symptoms suspicious of HAE, the levels of C1-INH activity and C4 should be measured.

Laboratory testing for C1 inhibitor deficiency: a comparison of two approaches to C1 inhibitor function

Background: C1 inhibitor deficiency may be hereditary or acquired. It is characterized by absent or poorly functioning C1 inhibitor. The disorder is rare, with prevalence estimated at 1/50,000. The very low incidence of the condition makes the sensitivity and specificity of assays used particularly important. Two different methods are commercially available to measure C1 inhibitor function. There are few data comparing these assays.

Methods: Two assays of C1 inhibitor function (C1 inhibitor-C1s complex formation or inhibition of C1 esterase cleavage of artificial substrate [colorimetric]) were compared in 71 patients (28 hereditary angioedema, 2 acquired angioedema and 41 controls).

Results: Qualitatively, the two assays showed good correspondence (92%). Six of 71 results were discordant. Correlation in quantitative terms was moderate ( R = 0.81).

Conclusions: Both assays show high sensitivity for hereditary/acquired angioedema. The colorimetric assay is more prone to false-positive results. However, clinical interpretation is not adversely affected.

A nationwide study of acquired C1-inhibitor deficiency in France: Characteristics and treatment responses in 92 patients

Acquired angioedema (AAE) due to C1-inhibitor (C1INH) deficiency is rare. Treatment options for acute attacks are variable and used off-label. Successful treatment of the associated lymphoma with rituximab seems to prevent acute attacks in subjects with AAE. The aim of this study was to describe AAE manifestations, its associated diseases, and patients' responses to treatments in a representative cohort.A retrospective nationwide study was conducted in France. The inclusion criteria were recurrent angioedema attacks and an acquired decrease in functional C1INH <50% of the reference value.A total of 92 cases were included, with a median age at onset of 62 years. Facial edema and abdominal pain were the most frequent symptoms. Fifteen patients were hospitalized in the intensive care unit because of laryngeal edema, and 1 patient died. Anti-C1INH antibodies were present in 43 patients. The associated diseases were primarily non-Hodgkin lymphoma (n = 44, with 24 splenic marginal zone lymphomas) and monoclonal gammopathy of undetermined significance (n = 24). Three patients had myeloma, 1 had amyloid light-chain (of immunoglobulin) (AL) amyloidosis, 1 patient had a bronchial adenocarcinoma, and 19 patients had no associated disease. Icatibant relieved the symptoms in all treated patients (n = 26), and plasma-derived C1INH concentrate in 19 of 21 treated patients. Six patients experienced thromboembolic events under tranexamic acid prophylaxis. Rituximab prevented angioedema in 27 of 34 patients as a monotherapy or in association with chemotherapy. Splenectomy controlled AAE in 7 patients treated for splenic marginal zone lymphoma. After a median follow-up of 4.2 years, angioedema was on remission in 52 patients.AAE cases are primarily associated with indolent lymphoma-especially splenic marginal zone lymphoma-and monoclonal gammopathy of undetermined significance but not with autoimmune diseases or other conditions. Icatibant and plasma-derived C1INH concentrate control attacks; splenectomy and immunochemotherapy prevent angioedema in lymphoma setting.

[Hereditary angioedema: strange cause of abdominal pain]

BACKGROUND

Hereditary angioedema is an episodic swelling disorder with autosomal dominant inheritance characterized by sudden attacks of peripheral swelling. Patients also commonly have episodic swelling of the wall of hollow viscera, including the bowel.

CLINICAL CASE

We present a 33-year-old previously healthy male with a complaint of acute-onset intense abdominal pain localized in the epigastrium. Pain irradiated to the right lower quadrant and was associated with five episodes of vomiting. Computed tomography showed thickening of the duodenal wall with liquid in the subphrenic space. Complementary laboratory tests showed low C4 complement levels (5.5 mg/dl) and 30% complement C1 inhibitor activity.

CONCLUSIONS

Hereditary angioedema is caused by a deficiency (type I) or dysfunction (type II) in complement C1 inhibitor. Abdominal associated with angioedema may manifest as severe acute-onset abdominal pain or as moderately severe chronic recurrent abdominal pain. Two medications are currently FDA-approved for the treatment of these patients.

Switch to icatibant in a patient affected by hereditary angioedema with high disease activity: a case report

Icatibant, an antagonist of the bradykinin B2 receptor, was approved for the treatment of acute attacks of hereditary angioedema in the EU in 2008. This paper presents the case of a 65-year-old woman affected by frequent acute attacks of hereditary angioedema who benefitted from a change of therapy to icatibant, following years of treatment with C1-inhibitor.

High levels of acute phase proteins and soluble 70 kDa heat shock proteins are independent and additive risk factors for mortality in colorectal cancer

Recently, we reported that high soluble Hsp70 (sHsp70) level was a significant predictor of mortality during an almost 3-year-long follow-up period in patients with colorectal cancer. This association was the strongest in the group of <70-year-old female patients as well as in those who were in a less advanced stage of the disease at baseline. According to these observations, measurement of the serum level of sHsp70 is a useful, stage-independent prognostic marker in colorectal cancer, especially in patients without distant metastasis. Since many literature data indicated that measurement of C-reactive protein (CRP) and other acute phase proteins (APPs) may also be suitable for predicting the mortality of patients with colorectal cancer, it seemed reasonable to study whether the effect of sHsp70 and other APPs are related or independent. In order to answer this question, we measured the concentrations of CRP as well as of other complement-related APPs (C1 inhibitor, C3, and C9) along with that of the MASP-2 complement component in the sera of 175 patients with colorectal cancer and known levels of sHsp70, which have been used in our previous study. High (above median) levels of CRP, C1 esterase inhibitor (C1-INH), and sHsp70 were found to be independently associated with poor patient survival, whereas no such association was observed with the other proteins tested. According to the adjusted Cox proportional hazards analysis, the additive effect of high sHsp70, CRP, and C1-INH levels on the survival of patients exceeded that of high sHsp70 alone, with a hazard ratio (HR) of 2.83 (1.13-70.9). In some subgroups of patients, such as in females [HR 4.80 (1.07-21.60)] or in ≤70-year-old patients [HR 11.53 (2.78-47.70)], even greater differences were obtained. These findings indicate that the clinical mortality-prediction value of combined measurements of sHsp70, CRP, and C1-INH with inexpensive methods can be very high, especially in specific subgroups of patients with colorectal cancer.

Potential biomarkers of an exaggerated response to endotoxemia

Serial plasma protein analysis was used to study the acute plasma proteome response to endotoxemia (presence of toxic bacterial products called endotoxins in the blood stream). Plasma samples from healthy volunteers before and multiple time points up to 24 h following administration of low-dose endotoxin were evaluated. Plasma protein profiles were obtained by rapid extraction of whole plasma followed by analysis with matrix-assisted laser desorption ionisation-time of flight mass spectrometry. The profiles were unique to each individual and stable over the time of the experiment. Administration of low-dose endotoxin caused profound change in six of 18 individuals. At 8 h many proteins showed quantitative oxidation, in addition to the appearance of new components and disappearance of common baseline components. An exceptionally intense new component at 4154 mass units was identified as the activation peptide of C1 esterase inhibitor. While recovery of baseline protein structure was nearly complete by 24 h, serum amyloid A, an acute-phase reactant, was still increasing and minor profile changes persisted. Clinical features did not distinguish these extreme responders from others, suggesting that plasma proteome changes offered unique insights into and potential biomarkers of subclinical events following endotoxin exposure.

A case of angioedema associated with decreased C1 inhibitor activity

BACKGROUND

We report a case of a 31-year-old woman who began to notice swelling of her arms at age 20. She was once given a diagnosis of cellulitis, but her symptoms spontaneously resolved. The patient had swelling of the left forearm and palm and was referred to our department for evaluation. She had slight pain but no obvious weight gain.

CASE SUMMARY

Antinuclear antibody and other autoantibodies, including anti-ds-DNA antibody, anti-RNP antibody, anti-Sm antibody, and anti-SS-A antibody were not detected. C1 inhibitor activity was low, C3 was normal, C4 was low, CH(50) was low, and C1q was normal.

DISCUSSION

Based on the presence of the typical clinical features and the positive results on the complement tests, we diagnosed hereditary angioedema. A decrease in C1 inhibitor activity and an increase in specific protein concentrations indicated type 1.

An evaluation of tests used for the diagnosis and monitoring of C1 inhibitor deficiency: normal serum C4 does not exclude hereditary angio-oedema

Reduced levels of serum C4 have been considered a ubiquitous finding in hereditary angio-oedema (HAE), and consequently low C4 is often used to 'request manage' access to C1 inhibitor assays in the United Kingdom. However, in our experience normal C4 may occasionally be compatible with HAE. We audited the results of serum C4, C1 inhibitor antigen (C1inhA) and C1 inhibitor function (C1inhF) in 49 HAE patients, compared to a control group of 58 unaffected subjects. The sensitivity of low serum C4 for HAE among untreated patients was 81%; levels of complement C4 were within the normal range on nine separate occasions in five untreated HAE patients. Molecular genetic analysis of these individuals demonstrated novel mutations in the C1 inhibitor gene. The supplied reference ranges for the Quidel C1inhF enzyme-linked immunosorbent assay (ELISA) system appear to be too low, with a sensitivity of just 57% for HAE. Following optimization of the reference ranges using receiver operating characteristic analysis, low C1inhF was found to be 78% sensitive and 100% specific for HAE. The diagnosis of HAE is not excluded by normal levels of complement C4. We conclude that C1 inhibitor studies should be performed regardless of serum C4 where a high index of clinical suspicion exists.

Acquired C1-esterase inhibitor deficiency and positive lupus anticoagulant accompanied by splenic marginal zone B-cell lymphoma

A 70-year-old woman complained of mild shortness of breath. Laboratory findings revealed pancytopenia, positive lupus anticoagulant and severe hypocomplementemia without anti-nuclear or anti-DNA antibodies. After the failure of prednisolone treatment, an acquired C1-esterase inhibitor (C1-INH) deficiency was diagnosed. There were no episodes of angioedema or deep vein thrombosis. Three months later, extreme splenomegaly was detected. Lymph node biopsy suggested splenic marginal zone B-cell lymphoma. Acquired C1-INH deficiency due to a lymphoproliferative disorder should be considered as a possible diagnosis for patients with severe hypocomplementemia.

Acquired angioedema in non-Hodgkin’s lymphoma

This paper describes a middle-aged patient who developed repeated episodes of swelling of the orofacial tissues after dental treatment. On investigation, C1 inhibitor, C1q, C2, and C4 levels were all markedly reduced, and a diagnosis of acquired C1 inhibitor deficiency was made. The patient had been diagnosed with non-Hodgkin's lymphoma (NHL) 2 years previously and had undergone a successful course of chemotherapy. The development of her episodes of angioedema prompted thorough reinvestigation and a recurrence of NHL was identified. Therefore, acquired C1 inhibitor deficiency heralded a recurrence, although this had not been a manifestation when NHL was first diagnosed. The patient underwent a further course of chemotherapy and remains well, although C1 inhibitor, C1q, C2, and C4 levels remain reduced.

[Practical management of C1 inhibitor deficiency]

C1 inhibitor deficiency is a rare syndrome clinically characterized by recurrent episodes of swelling of subcutaneous tissue or angioedema. It can involve the skin, upper respiratory airways and abdomen. There are two main types: hereditary and acquired. Angioedema can involve practically any part of the cutaneous surface, it can cause lethal laryngeal edema and can present as gastrointestinal obstruction. The attacks can be triggered, in general, by trauma, drugs or infections. Diagnosis is confirmed by decreased serum levels of C4 and absence or marked decrease of the level or function of C1 inhibitor. Commonly employed drugs for prophylaxis and treatment of these patients include anabolic steroids, antifibrinolytic agents, and infusion of C1 inhibitor concentrate. Fresh frozen plasma is an option to be considered for short term prophylaxis or treatment of the acute attack. It is convenient to know this syndrome as it is a potentially life-threatening disease. Diagnosis of this rare syndrome is based on clinical features and characteristic alterations of laboratory tests. The acute attack should be treated as quickly as possible. Prophylactic therapy is indicated in certain circumstances (dental procedures, oral surgery).

[Atypical presentation of hereditary angioedema. A report of a case and literature review]

Hereditary angioedema is an uncommon disorder mainly caused by defects of the gene for C1 inhibitor. These patients present recurrent edema episodes in the different regions of the body, including larynx edema in some cases. Low plasma levels of C1 inhibitor confirm the diagnosis. It is important to establish an early diagnosis and prompt treatment to this disorder due to its potential of fatal consequences and multiple alterations in the quality of life that have been associated with. The indicated treatment is substitutive therapy of C1 inhibitor concentrate. We present the case of a patient a 27 year-old female with a history of seven years of evolution, with daily periorbital, upper and lower extremities and labial edema episodes who was classified as C1 inhibitor deficiency type II. She began treatment with attenuated androgens in progressive increased doses with poor response, appearing torpid evolution without a favorable response. This case corresponds to a very atypical presentation of C1 inhibitor deficiency with daily symptoms, unlike the typical intermittent course of the classic disease.

Hereditary angio-oedema with normal C1 inhibitor in a family with affected women and men

Recurrent angio-oedema is a sign of various acquired and inherited disease entities, including hereditary angio-oedema types I and II that result from a genetic deficiency of C1 inhibitor, and a recently described type of dominantly inherited angio-oedema, which does not show a deficiency of C1 inhibitor. Until now, this new type of hereditary angio-oedema, designated as hereditary angio-oedema type III, has been assumed to be a disorder specific to females. We now describe a four-generation family with dominantly inherited angio-oedema and normal C1 inhibitor in which, in contrast to all previous observations, not only five female but also three male family members were clinically affected. One male patient was mainly affected following the intake of angiotensin-converting enzyme inhibitors. Our current observation leads to new considerations about the classification of hereditary angio-oedema with normal C1 inhibitor. Either hereditary angio-oedema with normal C1 inhibitor can be an entity affecting females predominantly, but not exclusively; in that case, men appear to have a much reduced chance of clinical manifestations. Alternatively, our present observation of hereditary angio-oedema with normal C1 inhibitor affecting both sexes may represent a new disease entity, presumably with a different underlying defect.

Acquired C1-inhibitor deficiency in a patient with systemic lupus erythematosus: a case report and review of the literature

The C1-inhibitor (C1-INH) is an important member of the serpin family which inhibits the first component of the human complement system and controls contact activation of the coagulation and kinin system. An acquired form of C1-INH deficiency was recognized and classified as type I, which is characterized by accelerated catabolism of C1-INH, whereas type II is defined by the presence of an autoantibody directed against the C1 inhibitor molecule. This study reports the case of a 32-year-old woman with systemic lupus erythematosus (SLE) who experienced recurrent angioedema because of an acquired C1-INH deficiency. The relevant literature is reviewed.