Definition and classification of hereditary angioedema

Assessment of clinical phenotypic characteristics of patients with angioedema without wheals in a turkish population

Background: Angioedema (AE) is defined as localized, self-limited swelling of subcutaneous tissues and mucosa. Objective: The aim of this study was to compare the phenotypic characteristics of patients with AE without wheals. Methods: This prospective study included adult patients with recurrent AE without wheals. Demographic and laboratory data of the patients were recorded in the patient file when they presented to the outpatient clinic between August 2018 and August 2020. The patients were contacted by phone to evaluate whether their AE had gone into remission between October 2023 and January 2024. The phenotypic characteristics of AE subtypes were compared. Results: The study included a total of 143 patients. The average age, age of onset of AE, rates of diabetes mellitus, hypertension and coronary artery disease were higher in the patients with angiotensin-converting enzyme inhibitor (ACEI) use related acquired AE (AAE) (AAE-ACEI). The rates of allergic rhinitis, drug allergy, atopy, and aeroallergen sensitivity, and the median total immunoglobulin E level were higher in patients with idiopathic histaminergic AAE (AAE-IH). The rate of face and/or perioral AE attacks was higher in the patients with AAE-ACEI, AAE-IH, and idiopathic non-histaminergic AAE. The rate of AE attacks in limbs, abdominal, genital and other parts of the body was higher in patients with hereditary AE (HAE). The baseline AE activity score was lower in the patients with AAE-IH and higher in the patients with HAE. In long-term follow-up, the remission rate of AE attacks was significant higher in patients with AAE-ACEI and AAE-IH. Conclusion: The phenotypic characteristic features of Turkish patients with AE without wheals may vary, depending on the underlying AE pathogenesis. C1 inhibitor level and function, complement C4 and C1q, and genetic tests contributed to the diagnosis; other laboratory tests did not contribute to the diagnosis.

Exploring disease-specific metabolite signatures in hereditary angioedema patients

Introduction

Hereditary angioedema (HAE) is a rare, life-threatening autosomal dominant genetic disorder caused by a deficient and/or dysfunctional C1 esterase inhibitor (C1-INH) (type 1 and type 2) leading to recurrent episodes of edema. This study aims to explore HAE patients' metabolomic profiles and identify novel potential diagnostic biomarkers for HAE. The study also examined distinguishing HAE from idiopathic angioedema (AE).

Methods

Blood plasma samples from 10 HAE (types 1/2) patients, 15 patients with idiopathic AE, and 20 healthy controls were collected in Latvia and analyzed using LC-MS based targeted metabolomics workflow. T-test and fold change calculation were used to identify metabolites with significant differences between diseases and control groups. ROC analysis was performed to evaluate metabolite based classification model.

Results

A total of 33 metabolites were detected and quantified. The results showed that isovalerylcarnitine, cystine, and hydroxyproline were the most significantly altered metabolites between the disease and control groups. Aspartic acid was identified as a significant metabolite that could differentiate between HAE and idiopathic AE. The mathematical combination of metabolites (hydroxyproline * cystine)/(creatinine * isovalerylcarnitine) was identified as the diagnosis signature for HAE. Furthermore, glycine/asparagine ratio could differentiate between HAE and idiopathic AE.

Conclusion

Our study identified isovalerylcarnitine, cystine, and hydroxyproline as potential biomarkers for HAE diagnosis. Identifying new biomarkers may offer enhanced prospects for accurate, timely, and economical diagnosis of HAE, as well as tailored treatment selection for optimal patient care.

Hereditary or acquired? Comprehensive genetic testing assists in stratifying angioedema patients

Hereditary angioedema (HAE) poses diagnostic challenges due to its episodic, non-specific symptoms and overlapping conditions. This study focuses on the genetic basis of HAE, particularly focusing on unresolved cases and those with normal C1-inhibitor levels (nC1-INH HAE). This study reveals that conventional testing identified pathogenic variants in only 10 patients (n = 32), emphasizing the necessity for an integrative approach using genome, exome, and transcriptome sequencing. Despite extensive genetic analyses, the diagnostic yield for nC1-INH HAE remains low in our study, the pathogenic variant for nC1-INH HAE was identified in only 1 patient (n = 21). Investigation into candidate genes yielded no pathogenic variants, prompting a re-evaluation of patients' diagnoses. This study advocates for a nuanced approach to genetic testing, recognizing its limitations and emphasizing the need for continuous clinical assessment. The complex genetic landscape of nC1-INH HAE necessitates further research for a more comprehensive understanding. In conclusion, this study contributes valuable insights into the genetic intricacies of HAE, highlighting the challenges in diagnosis and the evolving nature of the disease. The findings underscore the importance of advanced sequencing techniques and an integrated diagnostic strategy in unravelling the complexities of HAE, particularly in nС1-INH HAE cases.

Once-Daily Oral Berotralstat for Long-Term Prophylaxis of Hereditary Angioedema: The Open-Label Extension of the APeX-2 Randomized Trial

BACKGROUND

Berotralstat is a first-line, once-daily oral plasma kallikrein inhibitor approved for prophylaxis of hereditary angioedema (HAE) attacks in patients 12 years or older.

OBJECTIVE

This analysis examined the safety and effectiveness of long-term prophylaxis with berotralstat.

METHODS

APeX-2 was a phase 3, parallel-group, multicenter trial in patients with HAE caused by C1-inhibitor deficiency (NCT03485911). Part 1 was a randomized, double-blind, placebo-controlled evaluation of 150 and 110 mg of berotralstat over 24 weeks. In part 2, berotralstat-treated patients continued the same treatment, and placebo-treated patients were re-randomized to 150 or 110 mg of berotralstat for 24 weeks. In part 3, all patients were treated with open-label berotralstat at 150 mg, which could be continued for up to an additional 4 years. In part 3, the primary endpoint was long-term safety and tolerability. Secondary endpoints included HAE attack rates and quality of life (QoL).

RESULTS

Eighty-one patients entered part 3. Treatment-emergent adverse events (TEAEs) occurred in 82.7% of patients, with most being mild or moderate in severity. The most common TEAEs were nasopharyngitis, urinary tract infection, abdominal pain, arthralgia, coronavirus infection, and diarrhea. Drug-related TEAEs occurred in 14.8% of patients, but none were serious. For patients who completed 96 weeks of berotralstat treatment (n = 70), the mean (standard error) change in attack rate from baseline was -2.21 (0.20) attacks/mo. Clinically meaningful improvements in QoL were also observed, with the largest improvements in the functioning domain.

CONCLUSION

Berotralstat was generally well tolerated, provided rapid and sustained reductions in HAE attacks and improved QoL over 96 weeks.

Berotralstat for long-term prophylaxis of hereditary angioedema in Japan: Parts 2 and 3 of the randomized APeX-J Phase III trial

Background

Berotralstat is a once-daily oral inhibitor of plasma kallikrein for the prophylaxis of hereditary angioedema (HAE) in patients ≥12 years. APeX-J aimed to evaluate the efficacy and safety of berotralstat in Japan.

Methods

APeX-J was a Phase III trial comprising 3 parts (NCT03873116). Part 1 was a randomized, placebo-controlled evaluation of berotralstat 150 or 110 mg over 24 weeks. Part 2 was a 28-week dose-blinded phase in which berotralstat-treated patients continued the same dose and placebo patients were re-randomized to berotralstat 150 or 110 mg. In Part 3, all patients remaining on study received berotralstat 150 mg in an open-label manner for up to an additional 52 weeks. The primary endpoint of Parts 2 and 3 was long-term safety and tolerability, and secondary endpoints examined effectiveness.

Results

Seventeen patients entered Part 2, and 11 continued into Part 3. Treatment-emergent adverse events (TEAEs) were reported by 14/17 patients (82.4%) in Parts 2 or 3; the most common were nasopharyngitis, abdominal pain, cystitis, influenza, and vertigo. One patient (5.9%) experienced a drug-related TEAE (Grade 4 increased hepatic enzyme). No drug-related serious TEAEs were reported. For patients who completed 26 months of treatment with berotralstat 150 mg (n = 5), mean (standard error of the mean) monthly HAE attack rates and on-demand medication use decreased from baseline by 1.15 (0.09) attacks/month and 2.8 (0.64) doses/month, respectively. Sustained improvements were also observed in patient quality of life and treatment satisfaction.

Conclusions

Long-term prophylaxis with berotralstat raised no new safety signals and was effective at reducing attacks and improving patient-reported outcomes.

Trial registration

ClinicalTrials.gov NCT03873116. Registered March 13, 2019. Retrospectively registered.

The analysis of the effect of the COVID-19 pandemic on patients with hereditary angioedema type I and type II

Due to the similarity between the pathomechanism of SARS-CoV-2 infections and hereditary angioedema due to C1-inhibitor deficiency (C1-INH-HAE), a possibility emerged that C1-INH-HAE may worsen the course of the infection, or that the infection may influence the severity of angioedema (HAE) attacks in C1-INH-HAE patients. Our study aimed to evaluate the effects of the COVID-19 pandemic on the quality of life (QoL) of Hungarian C1-INH-HAE patients, and to survey the acute course of the infection, post COVID symptoms (PCS), vaccination coverage and the side effects of vaccines in this patient population. 93 patients completed our questionnaire between 1st July 2021 and 31st October 2021. In this same period and between March 2019 and March 2020, 63 patients completed the angioedema quality of life questionnaire (AE-QoL). Out of those patients infected with SARS-CoV-2 in the examined period (18/93 patients; 19%), 5% required hospitalization, 28% experienced HAE attacks in the acute phase of the infection, and 44% experienced PCS. A total number of 142 doses of vaccines were administered to the patients. Serious vaccine reactions did not occur in any case, 4 (5%) out of the 73 vaccinated patients experienced HAE attacks. No significant difference (p = 0.59) was found in the median of the AE-QoL total score, or in the number of HAE attacks prior and during the pandemic. Based on our study, HAE patients did not experience more serious SARS-CoV-2 infection, and it did not aggravate the course of HAE either. Changes in the QoL were not significant, and vaccines were safe in HAE patients.

Recurrent abdominal pain as the only clinical manifestation of hereditary angioedema type II

Recurrent abdominal pain is a common reason for consultation in Gastroenterology. The differential diagnosis includes hereditary angioedema (HAE), a rare disorder characterized by recurrent episodes of angioedema, without urticaria or pruritus, which most often affects the skin, but also mucosal tissues of the gastrointestinal tract, triggered by diverse factors such as infections, trauma, surgery, drugs, or stress. It is a disease with a difficult diagnosis due to its heterogeneous and transitory clinical features, so having a clinical suspicion in the appropriate context would allow the administration of a specific treatment and avoid unnecessary examinations. We present the case of a 19-year-old male followed-up for recurrent abdominal pain that, after numerous microbiological, endoscopic, and radiological examinations, complement tests were requested, obtaining low levels of C4 with increased levels of C1 inhibitor and reduced functional activity, being diagnosed with HAE type II.

National survey on clinical and genetic characteristics of patients with hereditary angioedema in Latvia

BACKGROUND

Hereditary angioedema (HAE) is a rare and life-threatening inborn error of immunity. HAE is mostly caused by pathogenic variations in the serine protease inhibitor gene 1 (SERPING1), leading to deficient or dysfunctional C1-inhibitor (C1-INH), overproduction of bradykinin, and development of recurrent subcutaneous and/or submucosal oedema. The prevalence of HAE is 1 in 50,000 - 100000 people worldwide. We aimed to describe the clinical features and genetic spectrum of hereditary angioedema with C1-INH deficiency (C1-INH-HAE) in Latvia.

METHODS

All patients from Latvia diagnosed with HAE (types I/II) from 2006 to March 2022 were included in the study. Laboratory tests and clinical data were analysed, and genetic tests with Sanger sequencing and whole genome sequencing were performed.

RESULTS

The study identified 10 C1-INH-HAE patients (nine females, one male) from eight families. The point prevalence of HAE in Latvia is 0.53 per 100 000 inhabitants. Of all patients, seven (70%) had HAE type I and three (30%) had HAE type II. The median age of patients was 54 years and the median age at onset of symptoms was 15 years. A significant delay (median 20.5 years) until diagnosis was observed, and 60% of patients had a positive family history of angioedema. All HAE patients have been hospitalised a median two times during their lifetime. Skin (100%), abdominal (80%), and airway (80%) oedema were the most frequent symptoms. Triggering factors (60%) and prodromal symptoms (90%) were referred. Attacks were severe in 50% of patients, moderate in 10%, and mild in 40%. Pathogenic variations of SERPING1 were identified in eight patients (six families), confirming the diagnosis molecularly. In two patients (two families), no pathogenic variations in the genes were found even after whole genome sequencing.

CONCLUSIONS

Current data shows a significant delay and clear underdiagnosis of HAE in Latvia. Higher awareness and better information and communication between doctors would improve the diagnosis and management of HAE; as would screening of family members, patients with recurrent angioedema unresponsive to antihistamines and glucocorticoids, and patients with recurrent episodes of severe, unexplained abdominal pain.

High digit ratio (2D:4D) is associated with attack frequency and severity in hereditary angioedema patients

BACKGROUND

Hereditary angioedema (HAE) caused by a deficiency or dysfunction of the plasma protease C1-inhibitor is a rare autosomal-dominant disorder. We explored a possible correlation between the ratio of the second and fourth finger lengths (2D:4D) and the frequency of HEA attacks, and whether the ratio might predict laryngeal attack.

METHOD

We evaluated 35 HEA patients aged 19 to 66 years; 3 were subsequently excluded. The 2D:4D ratio was calculated by dividing the length of the second finger by that of the fourth finger of both hands. A structured clinical questionnaire exploring HAE course and treatment over the prior year was administered.

RESULTS

Of the 32 participants, 56.25 % (n = 18) were female. Of them, those with high 2D:4D ratios suffered significantly more laryngeal attacks than others; 93.3% of patients with high 2D:4D ratios experienced ≥5 attacks annually, significantly more than those with low ratios. Among type 2 HEA patients, 75 % of those experiencing ≥5 attacks annually had high 2D:4D ratios; all patients with low 2D:4D ratios reported <5 attacks annually. These significant effects were found for right-hand 2D:4D ratios and not left-hand 2D:4D ratios.

CONCLUSION

The data suggest that intrauterine sex hormone exposure, which affects the 2D:4D ratio, is significantly associated with HEA attack frequency and severity, and laryngeal edema.

Hereditary Angioedema During Pregnancy: Considerations in Management

In recent years, hereditary angioedema (HAE) management has substantially advanced but also become more complex with additional therapeutic options. Pregnancy significantly influences the clinical symptoms of HAE in many women because of estrogen effects or other physiologic factors, and also introduces important safety concerns related to HAE medications. Management of HAE during pregnancy requires clinicians to be familiar with the potential clinical course, triggers, and recommended treatment strategies to provide guidance and optimal medical management to women and families affected by the condition. This review provides an overview of data, considerations, and recommendations related to HAE and pregnancy.

A patient with hereditary angioedema (HAE) with normal C1-INH and SLE with pregnancy

The case of a 24-year-old female patient with hereditary angioedema, a normal C1 esterase inhibitor level, SLE, and pregnancy is reported.

Characteristics of Patients Who Underwent a Diagnostic Test for Hereditary Angioedema Admitted Due to Angioedema

OBJECTIVE

Hereditary angioedema (HAE) is clinically characterized by recurrent attacks of angioedema. This study evaluated the clinical findings and examination results of patients admitted due to angioedema who then underwent a diagnostic test for HAE. The study aimed to assess the contribution of laboratory findings to the diagnostic process and to determine clinicians' level of awareness regarding the differential diagnosis of angioedema and the appropriate laboratory tests.

METHODS

Pediatric patients suspected to have HAE based on the presence of angioedema and screened for C1 esterase inhibitor levels and/or function were included in the study.

RESULTS

A total of 136 patients were evaluated for a preliminary diagnosis of HAE in the presence of angioedema. Angioedema was accompanied by urticaria in 65 patients (47.7%) and itching in 24 patients (17.6%). Patients were evaluated using laboratory tests, C4 levels were studied in 124 patients (91.1%) and were found to be within normal reference limits. C1 esterase inhibitor levels were studied in all patients and were found to be within normal limits. C1 esterase inhibitor function was also studied in 101 patients (74.2%) and was found to be within normal limits.

DISCUSSION

It was concluded that clinicians keep HAE in mind when encountering angioedema, but that increasing their knowledge of clinical findings that assist in differential diagnosis among angioedema types would be useful. The study authors would like to emphasize that this topic should be included in the specialty training curriculum to raise the awareness of clinicians, especially pediatricians, about clinical HAE findings and the algorithmic approach to the differential diagnosis of angioedema.

The international WAO/EAACI guideline for the management of hereditary angioedema - The 2021 revision and update

Hereditary Angioedema (HAE) is a rare and disabling disease for which early diagnosis and effective therapy are critical. This revision and update of the global WAO/EAACI guideline on the diagnosis and management of HAE provides up-to-date guidance for the management of HAE. For this update and revision of the guideline, an international panel of experts reviewed the existing evidence, developed 28 recommendations, and established consensus by an online DELPHI process. The goal of these recommendations and guideline is to help physicians and their patients in making rational decisions in the management of HAE with deficient C1-inhibitor (type 1) and HAE with dysfunctional C1-inhibitor (type 2), by providing guidance on common and important clinical issues, such as: 1) How should HAE be diagnosed? 2) When should HAE patients receive prophylactic on top of on-demand treatment and what treatments should be used? 3) What are the goals of treatment? 4) Should HAE management be different for special HAE patient groups such as children or pregnant/breast feeding women? 5) How should HAE patients monitor their disease activity, impact, and control? It is also the intention of this guideline to help establish global standards for the management of HAE and to encourage and facilitate the use of recommended diagnostics and therapies for all patients.

The international WAO/EAACI guideline for the management of hereditary angioedema-The 2021 revision and update

Hereditary angioedema (HAE) is a rare and disabling disease for which early diagnosis and effective therapy are critical. This revision and update of the global WAO/EAACI guideline on the diagnosis and management of HAE provides up-to-date guidance for the management of HAE. For this update and revision of the guideline, an international panel of experts reviewed the existing evidence, developed 28 recommendations, and established consensus by an online DELPHI process. The goal of these recommendations and guideline is to help physicians and their patients in making rational decisions in the management of HAE with deficient C1 inhibitor (type 1) and HAE with dysfunctional C1 inhibitor (type 2), by providing guidance on common and important clinical issues, such as: (1) How should HAE be diagnosed? (2) When should HAE patients receive prophylactic on top of on-demand treatment and what treatments should be used? (3) What are the goals of treatment? (4) Should HAE management be different for special HAE patient groups such as children or pregnant/breast-feeding women? and (5) How should HAE patients monitor their disease activity, impact, and control? It is also the intention of this guideline to help establish global standards for the management of HAE and to encourage and facilitate the use of recommended diagnostics and therapies for all patients.

Hereditary Angioedema: Diagnostic Algorithm and Current Treatment Concepts

Hereditary angioedema (HAE) is an uncommon disorder with a global prevalence of approximately 1 in 10,000 to 1 in 50,000 population. This disease is grossly underrecognized in India because of lack of awareness and/or lack of diagnostic facilities. Clinical manifestations include swelling over face, eyes, lips, hands, feet, and genitals, abdominal pain, and life-threatening laryngeal edema. HAE should be suspected in all patients who present with angioedema without wheals and who do not respond to antihistamines and/or steroids. C1 levels, C1-INH levels, and C1-INH function should be checked in all patients suspected to have HAE. C1q levels should be assessed in patients with suspected autoimmune-mediated acquired angioedema. Management of HAE constitutes the treatment of acute attack and short-term and long-term prophylaxis. Because of lack of all first-line recommended medications, the management of HAE in India is a challenging task. Patients are managed using fresh frozen plasma (acute treatment), tranexamic acid, and attenuated androgens (prophylaxis). Even though attenuated androgens have been shown to be effective in the prevention of attacks of HAE, the side effect profile especially in children and in females is a serious concern. Hence, the treatment needs to be individualized considering the risk-benefit ratio of long-term prophylaxis. In this review, we provide an overview of diagnostic strategy for patients with HAE and the current treatment concepts with emphasis on currently available treatment options in resource-constrained settings.

Small molecule drugs for atopic dermatitis, rheumatoid arthritis, and hereditary angioedema

OBJECTIVE

To review recent trends in the development of targeted small molecule drugs (SMDs) for the treatment of immunologically driven disorders, including atopic dermatitis, rheumatoid arthritis, and hereditary angioedema.

DATA SOURCES

Data sources included peer-reviewed published literature from the PubMed database, published abstracts from scientific and medical meetings, and medication information from the Drugs@FDA database.

STUDY SELECTIONS

Articles with primary or retrospective trial results, articles with patient or physician survey results, articles providing expert perspectives, and commentary on chronic immunologic disorders, Food and Drug Administration package inserts, and abstracts from scientific meetings were selected.

RESULTS

Targeted biological therapies have greatly improved response rates and symptom relief for patients with long-term immunologically driven disorders over the past 2 decades. However, recent advances in the understanding of molecular pathways involved in the pathogenesis of these disorders have led to the development of novel targeted SMDs, such as tofacitinib and berotralstat, that can be delivered orally or topically. Few head-to-head studies that compare the safety and efficacy of biologics to SMDs in immunologically driven disorders exist, although some studies suggest that oral and topical modes of administration are preferred by patients and may improve patient quality of life over time.

CONCLUSION

Scientific advances have led to an increase in the development of targeted SMDs for the treatment of chronic immunologic disorders, which may revolutionize the management of these diseases. Head-to-head studies and real-world evidence are needed to fully compare treatment attributes between biologics and SMDs, including safety, efficacy, adherence, impact on quality of life, and cost-effectiveness.

Etiology and predictors of cluster attacks of hereditary angioedema that recur despite pharmaceutical treatment

Introduction: Hereditary angioedema (HAE) is a disease that leads to recurrent swelling of the skin and mucous membranes, including the upper airway tract. Apart from being deadly, these attacks can be debilitating, which leads to a poor quality of life in patients. Clinicians are occasionally confronted with patients who have recurrent attacks despite treatment with C1 esterase inhibitor concentrate or β₂-receptor antagonists. The goal of this study was to investigate repeated attacks that occur 48 hours to 7 days ("cluster attacks") after treatment, to determine why they occur and the factors that may be associated with them, and thus to prevent their occurrence. Methods: We conducted a multicenter mixed retrospective-prospective study with data acquired from all documented attacks in our patients with collective (n = 132) between 2015 and 2018. Results: Eighty-five percent (n = 132) of our total patient collective (N = 156) agreed to participate in the study. Nine percent of these patients (n = 12) had cluster attacks, with a total of 48 cluster attacks. The data procured from the patients were mixed retrospective-prospective. Approximately 72% of all the cluster attacks were caused by exogenous stimuli (41% due to psychological stress, 29% due to physical stimuli, and 2% due to menstruation). Cluster attacks occurred in 7% of the patients who received prophylactic therapy in comparison with 12.5% of patients who received on-demand therapy. Cluster attacks comprised 48.4% of all the attacks that patients with cluster-attacks (n= 9) experienced. In addition, the patients who were underdosing their C1 esterase inhibitor treatment had cluster attacks more often. A lower "time to repeated attack" was seen in the patients who received on-demand therapy compared with those who received prophylactic therapy. Discussion: The percentage of the patients who had attacks as a result of exogenous triggers was higher in the cluster-attack group (70.5%) compared with the general HAE population (30-42%). Repeated attacks, therefore, were strongly associated with external triggers. The patients who received prophylactic treatment and who experienced cluster attacks were highly likely to have been underdosing, which may explain the repeated attacks despite treatment. In the patients prone to cluster attacks, prophylaxis should be considered.

Hereditary angioedema: Comprehensive management plans and patient support

Hereditary angioedema (HAE) is a rare disease. Regardless, patients with HAE have access to multiple state-of-the-art medications available for on-demand use and prevention that reduce the frequency and burden of HAE attacks. These treatments have greatly reduced the burden of disease and helped patients achieve improved quality of life. However, with greater numbers of therapeutic options, HAE care has become more complex. In this review, we addressed essential elements of an individualized comprehensive management plan for a patient with HAE. We focused on access to an expert physician, ongoing patient education, access to effective treatment options, coordination of care and management of treatment logistics, ongoing monitoring of attacks and treatments, and other resources for patient support. This plan will need to be communicated with the patient and other care providers, especially during emergent conditions, and accommodate the patient's lifestyle with consideration for work, school, travel, etc. Periodically, the physician and the patient will need to review information about attacks, triggers, and treatments to identify areas for improvement and update the plan.

Hereditary angioedema: Differential diagnosis, diagnostic tests, and family screening

Hereditary angioedema is a rare, autosomal dominant genetic disorder that leads to sporadic episodes of swelling, which can affect any part of the body. With a prevalence of 1 in 10,000 to 1 in 50,000, there are other, more common causes of angioedema. Differentiating between bradykinin-mediated and histamine-mediated causes of swelling remains a major challenge. It is critical to develop an appropriate differential diagnosis, work through the various conditions, and obtain the pertinent laboratory evaluation to rule in or out the proposed diagnosis. As an autosomal dominant genetic disorder, there is a 50% chance with each pregnancy of passing on the genetic mutation in the SERPING1 gene. This review addressed the differential diagnosis to consider, the appropriate laboratory evaluation, and the importance of family screening.