Systematic Approach Revealed SERPING1 Splicing-Affecting Variants to be Highly Represented in the Czech National HAE Cohort

Hereditary angioedema due to C1 inhibitor deficiency (C1-INH-HAE) is a rare and life-threatening condition characterized by recurrent localized edema. We conducted a systematic screening of SERPING1 defects in a cohort of 207 Czech patients from 85 families with C1-INH-HAE. Our workflow involved a combined strategy of sequencing extended to UTR and deep intronic regions, advanced in silico prediction tools, and mRNA-based functional assays. This approach allowed us to detect a causal variant in all families except one and to identify a total of 56 different variants, including 5 novel variants that are likely to be causal. We further investigated the functional impact of two splicing variants, namely c.550 + 3A > C and c.686-7C > G using minigene assays and RT-PCR mRNA analysis. Notably, our cohort showed a considerably higher proportion of detected splicing variants compared to other central European populations and the LOVD database. Moreover, our findings revealed a significant association between HAE type 1 missense variants and a delayed HAE onset when compared to null variants. We also observed a significant correlation between the presence of the SERPING1 variant c.-21 T > C in the trans position to causal variants and the frequency of attacks per year, disease onset, as well as Clinical severity score. Overall, our study provides new insights into the genetic landscape of C1-INH-HAE in the Czech population, including the identification of novel variants and a better understanding of genotype-phenotype correlations. Our findings also highlight the importance of comprehensive screening strategies and functional analyses in improving the C1-INH-HAE diagnosis and management.

[Facial swelling due to angioedema: often mast cell mediated, but not always]

Most cases of angioedema are mast cell mediated. We present three patients with angioedema, who were admitted to our emergency room or outpatient clinic. One of them did have mast cell mediated angioedema, despite insufficient response to initial antihistamine treatment. The other patients had more rare cases of angioedema, i.e. hereditary angioedema with C1-inhibitor deficiency and angiotensin converting enzyme inhibitor associated angioedema. We discuss similarities and differences in symptoms, diagnosis and treatment between these causes of angioedema. We recommend keeping the differential diagnosis of angioedema in mind when a patient with angioedema is presented, including rarer pathophysiological explanations.

A Comprehensive Management Approach in Pediatric and Adolescent Patients With Hereditary Angioedema

Hereditary angioedema (HAE) is a rare autosomal-dominant disorder; most cases are characterized by low plasma levels of C1 esterase inhibitor (C1-INH). Clinical manifestations of HAE due to C1-INH deficiency include unpredictable, acute, recurrent episodes of nonpruritic swelling that can affect the face, trunk, limbs, and the respiratory, gastrointestinal, and genitourinary tracts. Attacks can be disfiguring, disabling, painful, and even life-threatening if laryngeal swelling occurs. Symptoms of HAE generally manifest in childhood. Effective medications are available and approved to treat HAE in children. However, evidence informing use of these medications in pediatric clinical practice is limited. Hereditary angioedema management plans are critical to optimize outcomes and should address on-demand treatment for acute attacks and plans to prevent potentially fatal laryngeal attacks. The plan should also comprise a holistic approach to address nonclinical aspects of HAE, including quality of life (QoL) and psychological issues. This article provides an overview of HAE management principles that health care providers can apply to treat pediatric patients to improve their QoL.

How Does Pregnancy and Type of Delivery Affect the Clinical Course of Hereditary Angioedema?

INTRODUCTION

Knowledge on the clinical course of hereditary angioedema (HAE) during pregnancy, delivery, and breastfeeding is very limited. In this study, we aimed to evaluate the course of HAE during these periods.

METHODS

The HAE attacks C1-INH prophylaxis before and during pregnancy and during breastfeeding, and the delivery types were retrospectively determined. The severity of attacks was assessed by a 10-point Visual Analogue Scale (VAS).

RESULTS

We evaluated 88 pregnancies in 48 HAE patients among whom 20 were primiparous. Among those who had a HAE diagnosis during pregnancy (n = 34), the median attack numbers before pregnancy, during pregnancy, breastfeeding, and after breastfeeding were 17, 39, 24, and 14 (before pregnancy vs. pregnancy, p < 0.001; during pregnancy vs. breastfeeding, p = 0.001). The mean VASs (SD) were 6.59 (1.82), 8.33 (1.58), 7.32 (1.66), and 6.95 (1.90) (before pregnancy vs. pregnancy, p < 0.001; during pregnancy vs. breastfeeding, p = 0.016), respectively. Among those who received a HAE diagnosis after pregnancy (n = 54), the number (59.3%) and the severity (60%) of HAE attacks were high in pregnancy. 47 of the deliveries were normal vaginal delivery (NVD). Regional anesthesia was applied in 8 NVDs. 20 of caesarean deliveries were performed under general anesthesia, and 21 were under spinal anesthesia. Lowest numbers of attacks were found in patients who did not receive anesthesia during NVD (p = 0.001).

CONCLUSION

The course of HAE can be worse during pregnancy and breastfeeding. NVD is related to fewer HAE attacks and prophylaxis with C1-INH during NVD is not necessary to prevent a HAE attack.

Hereditary angioedema: Patient journey approach in Mexico

Objective

To understand the patient's journey with HAE from symptom initiation to diagnosis, treatment allocation, follow-up, and the impact of the disease on their quality of life in Mexico.

Methods

A survey was administered to the patients with HAE. Participants completed a questionnaire covering five domains: patient journey; effects on productivity, school performance and daily activities; quality of life; anxiety and depression. Responses were analyzed using descriptive statistics.

Results

A total of 17 surveys were analyzed (15 women and 2 men, age range: 23-67 years). Type I HAE was most common (71%), normal C1 inhibitor HAE was 12% and 18% did not know their HAE type. The average disease evolution was 13.7 years and the time from symptom initiation to diagnosis was 20 years. 59% of patients knew of one or two treatments available, 12% knew 3 treatments and 18% were aware of 4 or more, 12% were not aware of any treatments. 53% had a job, 18% referred a severely anxious state, 41% were depressed and all patients referred some social impact due to HAE.

Conclusions

There is a need to reinforce the knowledge of general practitioners on HAE to promote an earlier diagnosis and awareness of rare diseases and their impact on quality of life among the general population and promote the removal of barriers to treatment.

Hereditary Angioedema With Normal C1 Inhibitor: US Survey of Prevalence and Provider Practice Patterns

BACKGROUND

Hereditary angioedema (HAE) with normal C1-INH (HAE-nl-C1INH) is phenotypically similar to HAE resulting from C1-INH deficiency (HAE-C1INH). Confirmatory diagnostic tests for HAE-nl-C1INH are limited and few clinical study data exist regarding management of the condition. Therefore, survey studies may provide initial estimates of prevalence, diagnosis, and management patterns of this condition.

OBJECTIVE

To estimate the prevalence and describe current management patterns for HAE-nl-C1INH in the United States (US).

METHODS

We conducted an Internet-based survey of US physicians to estimate the prevalence of the HAE-nl-C1INH population in the United States. Potential participating physicians were identified from the US Hereditary Angioedema Association database and IQVIA Xponent prescription database. Eligible physicians were invited to complete an online survey between June and September 2021.

RESULTS

A total of 113 physicians provided data for the estimation of HAE-nl-C1INH prevalence and 81 physicians treating HAE-nl-C1INH patients provided data about treatment patterns. In bias-corrected analysis, we estimated 1,230 to 1,331 HAE-nl-C1INH patients within the United States between May 2019 and April 2020. Mean time to diagnosis for HAE-nl-C1INH was approximately 6 years (range, 2.4-13.5 years). Response to medication was commonly used to inform diagnosis (antihistamine response or nonresponse used by 73% of physician respondents, corticosteroids by 57%, or HAE-specific medications by 74%), and Factor XII genetic testing was used by 43%.

CONCLUSIONS

These survey data provide estimates of HAE-nl-C1INH prevalence in the United States as well as current diagnosis and management strategies. Results may be useful for developing studies to assess treatment efficacy and safety, and potentially improve the diagnosis for and management of this patient population.

Hereditary Angioedema: A Review of the Current and Evolving Treatment Landscape

Hereditary angioedema (HAE) is a rare disease characterized by sudden and often unprovoked episodes of swelling that can be potentially life-threatening when it involves the upper airway. The treatment options for both acute episodes of HAE and LTP, used to minimize the frequency and severity of angioedema attacks, were limited historically to very few options, had considerable side effects, and/or had considerable burden of treatment. Fortunately, through the elucidation of the pathophysiology of HAE, the development of newer targeted therapies has been possible both for acute therapy and long-term prophylaxis and even more are on the horizon. Because of the rapid development of these therapies, it can be challenging for clinicians to keep abreast of newer and developing treatments for HAE. This review article will outline the current and potential future treatments for HAE. It will also highlight important considerations when treating special HAE patient populations including women and pediatric patients.

Genetic Variants Leading to Urticaria and Angioedema and Associated Biomarkers

Advances in next generation sequencing technologies, as well as their expanded accessibility and clinical use over the past 2 decades, have led to an exponential increase in the number of identified single gene disorders. Among these are primary atopic disorders-inborn errors of immunity resulting in severe allergic phenotypes as a primary presenting feature. Two cardinal aspects of type I immediate hypersensitivity allergic reactions are hives and angioedema. Mast cells (MCs) are frequent primary drivers of these symptoms, but other cells have also been implicated. Even where MC degranulation is believed to be the cause, mediator-induced symptoms may greatly vary among individuals. Angioedema-particularly in the absence of hives-may also be caused by hereditary angioedema conditions resulting from aberrant regulation of contact system activation and excessive bradykinin generation or impairment of vascular integrity. In these patients, swelling can affect unpredictable locations and fail to respond to MC-directed therapies. Genetic variants have helped delineate key pathways in the etiology of urticaria and nonatopic angioedema and led to the development of targeted therapies. Herein, we describe the currently known inherited and acquired genetic causes for these conditions, highlight specific features in their clinical presentations, and discuss the benefits and limitations of biomarkers that can help distinguish them.

Neurologic and Psychiatric Manifestations of Bradykinin-Mediated Angioedema: Old and New Challenges

Neurologic manifestations have been occasionally described in patients with bradykinin-mediated angioedema. The existing literature is currently limited to case series and case reports mainly described in the hereditary forms (HAE) concerning central nervous system (CNS) involvement. On the contrary, very little is known about peripheral and autonomic nervous system manifestations. CNS involvement in HAE may present with symptoms including severe headaches, visual disturbance, seizures, and various focal and generalized deficits. In addition, a stroke-like clinical picture may present in HAE patients. In turn, some drugs used in patients with cardiovascular and neurologic disorders, such as recombinant tissue plasminogen activator (r-tPA) and angiotensin-converting enzyme inhibitors (ACEI), may produce medication-induced angioedema, resulting in a diagnostic challenge. Finally, most patients with HAE have higher levels of psychological distress, anxiety, and depression. With this review, we aimed to provide an organized and detailed analysis of the existing literature on neurologic and psychiatric manifestations of HAE to shed light on these potentially invalidating symptoms and lay the foundation for further personalized diagnostic pathways for patients affected by this protean disease.

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.

Epidemiology, Management, and Treatment Access of Hereditary Angioedema in the Asia Pacific Region: Outcomes From an International Survey

BACKGROUND

Hereditary angioedema (HAE) is a rare genetic disease with significant morbidity and mortality for which early diagnosis and effective therapy are critical. Many Asia Pacific (AP) countries still lack access to diagnostic tests and evidence-based therapies. Epidemiologic data from the AP is needed to formulate regional guidelines to improve standards of care for HAE.

OBJECTIVE

To investigate the estimated minimal prevalence, needs, and potential interventions for the diagnosis and management of HAE in the AP.

METHODS

A structured questionnaire was distributed to representative experts from member societies of the Asia Pacific Association of Allergy, Asthma and Clinical Immunology. Patient profiles and the presence of diagnostic facilities or tests, regional and national HAE guidelines, and patient support groups were reported and compared.

RESULTS

Completed questionnaires were received from 14 representatives of 12 member countries and territories, representing 46% of the world population. Overall minimal prevalence of HAE in the AP region was 0.02/100,000 population, with significant heterogeneity across different centers. Only one-half and one-third had registered on-demand and prophylactic medications, respectively. Few had patient support groups (58%) or regional guidelines (33%), and their existence was associated with the availability of HAE-specific medications. Availability of C1-inhibitor level testing was associated with a lower age at HAE diagnosis (P = .017).

CONCLUSIONS

Hereditary angioedema in the AP differs from that in Western countries. Hereditary angioedema-specific medications were registered in only a minority of countries and territories, but those with patient support groups or regional guidelines were more likely to have better access. Asia Pacific-specific consensus and guidelines are lacking and urgently needed.

Insights into the pathogenesis of hereditary angioedema using genetic sequencing and recombinant protein expression analyses

BACKGROUND

The pathogenesis of hereditary angioedema (HAE) type I and type II is linked to defective C1 esterase inhibitor (C1-INH) encoded by the SERPING1 gene. There are substantial variabilities in the clinical presentations of patients with HAE that are not directly correlated to the serum levels of C1-INH. The impact of SERPING1 variants on C1-INH expression, structure, and function is incompletely understood.

OBJECTIVE

To investigate the influence of SERPING1 variants on the C1-INH expression, structure, and function of 20 patients with HAE from 14 families with no prior genetic diagnosis.

METHODS

Patients underwent whole-exome sequencing (WES). If no variants were identified, whole-genome sequencing (WGS) was performed. Except for the frameshift and large deletions, each C1-INH variant was recombinantly produced and, if synthesized and secreted, was subjected to structural, oligosaccharide, and functional analyses.

RESULTS

We identified 11 heterozygous variants in the SERPING1 gene, of which 5 were classified as pathogenic (E85Dfs∗63, N166Qfs∗91, K201Qfs∗56, P399A, and R466H) and 6 as variants of uncertain significance (C130W, I224S, N272del, K273del, L349F, and F471C). Three large heterozygous deletions were discovered through WGS. Our data indicate that C130W, N272del, P399A, and F471C are poorly synthesized, I224S prevents proper C1-INH folding, and K273del impairs C1-INH function by adding an additional oligosaccharide. Further evaluation suggests that compound variant P399A/L349F contributes to a more severe clinical phenotype.

CONCLUSIONS

Our combined approach of WES and WGS uncovered SERPING1 gene alternations in each patient. The recombinant protein production followed by systematic antigenic, structural, and functional assessment facilitates the identification of underlying pathogenic mechanisms in HAE.

Phenotypic and Genotypic Characterization of Hereditary Angioedema in Saudi Arabia

Hereditary angioedema (HAE) is a potentially life-threatening autosomal dominant disorder affecting roughly 1:50,000 individuals. It is commonly characterized by swelling of the larynx, gastrointestinal tract, extremities, and skin. There is growing genetic heterogeneity associated with this disease but more than 95% of mutations are found in SERPING1, the gene which encodes complement 1 inhibitor (C1-INH). HAE cohorts from several populations have been published but no large scale study has been reported from the Arab world to date. Here we document the clinical and genetic findings of HAE patients from a single Saudi institution, which is a major referral center at the national level. A total of 51 patients across 17 unrelated families were recruited including two large multi-generational families, of which one contained an in-frame exonic deletion that was resolved through MLPA. Two cases were negative for all the genes we tested (including F12, PLG, ANGPT1, MYOF, KNG1, and HS3ST6). The predominant HAE subtype in our cohort was type I, at 76%. We were able to uncover a mutation in 49 patients (96%). No type III (normal C1-INH) patients were encountered in the clinic, suggesting that this subtype does not play a major role in HAE pathogenesis in Saudi Arabia. Additionally, the existence of four patients with consistently normal complement 4 (C4) levels alongside abnormal C1-INH profiles highlights the utility of dual screening for both proteins in suspected patients.

A catalog of the genetic causes of hereditary angioedema in the Canary Islands (Spain)

Hereditary angioedema (HAE) is a rare disease where known causes involve C1 inhibitor dysfunction or dysregulation of the kinin cascade. The updated HAE management guidelines recommend performing genetic tests to reach a precise diagnosis. Unfortunately, genetic tests are still uncommon in the diagnosis routine. Here, we characterized for the first time the genetic causes of HAE in affected families from the Canary Islands (Spain). Whole-exome sequencing data was obtained from 41 affected patients and unaffected relatives from 29 unrelated families identified in the archipelago. The Hereditary Angioedema Database Annotation (HADA) tool was used for pathogenicity classification and causal variant prioritization among the genes known to cause HAE. Manual reclassification of prioritized variants was used in those families lacking known causal variants. We detected a total of eight different variants causing HAE in this patient series, affecting essentially SERPING1 and F12 genes, one of them being a novel SERPING1 variant (c.686-12A&gt;G) with a predicted splicing effect which was reclassified as likely pathogenic in one family. Altogether, the diagnostic yield by assessing previously reported causal genes and considering variant reclassifications according to the American College of Medical Genetics guidelines reached 66.7% (95% Confidence Interval [CI]: 30.1-91.0) in families with more than one affected member and 10.0% (95% CI: 1.8-33.1) among cases without family information for the disease. Despite the genetic causes of many patients remain to be identified, our results reinforce the need of genetic tests as first-tier diagnostic tool in this disease, as recommended by the international WAO/EAACI guidelines for the management of HAE.

The Role of Bradykinin Receptors in Hereditary Angioedema Due to C1-Inhibitor Deficiency

Background: Hereditary angioedema (HAE) is a rare, genetic disease caused by the decreased level or function of the C1 inhibitor. The primary mediator of symptoms in HAE is bradykinin acting through its two receptors, namely receptors 1 (BR1) and 2 (BR2). Although BR2 is well characterized, the role of BR1 remains unclear. Objective: To study the role of bradykinin receptors 1 (BR1) in the etiopathogenesis of HAE. Methods: A total of 70 individuals, 40 patients with HAE, and 30 healthy subjects were recruited to the study. HAE was diagnosed in accordance with the international guideline. The level of bradykinin receptors was determined in populations of CD3⁺, CD4⁺, CD8⁺, and CD14⁺⁺CD16⁻, CD14⁺⁺CD16⁺ monocytes. In addition, the level of disease activity-specific markers was measured. Results: There were statistically significant differences in the subpopulation of lymphocytes and monocytes between patients with HAE compared to healthy subjects. The level of BR1 and BR2 on PBMCs was comparable in healthy subjects and HAE patients during remission with significant overexpression of both receptors, triggered by HAE attack. Moreover, a significant increase in TNF-alpha and IL-1 plasma levels was observed among HAE patients. Conclusions: BR1 expression may play an important role in the pathomechanism of HAE.

Investigation of Mortality of Hereditary Angioedema in a Reference Center in Brazil

BACKGROUND

Hereditary angioedema (HAE) is known for mortality when it is not treated properly. Many advances have occurred over the past decades that affected patients' lives. However, not all patient populations have access to the same diagnosis and treatment resources.

OBJECTIVE

To evaluate mortality from HAE in a large cohort in a reference center in Brazil. Furthermore, the research intended to describe patients' life span, the asphyxia evolution, and factors related to the fatal outcome.

METHODS

A cohort of 433 patients from 46 families was evaluated in this prospective and retrospective study. Families were organized in clusters and were given a verbal autopsy to arrange data collection for the deaths and analyze symptoms during life. Causes of death were classified as deaths from laryngeal edema (LE) or other causes.

RESULTS

Of 433 patients evaluated, 254 were not given the diagnosis of HAE. A total of 75 fatal events were evaluated. Only 10 of 75 patients were given the diagnosis of HAE before death, and the HAE diagnosis was made after death in 65 of 75 patients using verbal autopsy. The final cause of death after the investigation was asphyxiation owing to LE in 39 of 75 (52%) and deaths owing to other causes in 36 of 75 (48%). Ten deaths had occurred in the past decade. Time from onset of symptoms to seeking medical assistance was a median of 4 hours, and the time to death was a median of 8 hours. Three patients received fresh-frozen plasma and none received medications specific to HAE attacks. Throat pain or discomfort was the most common symptom, experienced by 71.8% of patients. The most common mistaken diagnosis at the original death certificate was allergy or anaphylaxis. The life span of patients who died of LE was reduced by 20 years compared with those who died of other causes.

CONCLUSIONS

Hereditary angioedema remains a threat to life in the studied population. The large number of patients who do not receive a diagnosis makes the situation even more severe and is responsible for most deaths. Death analyses add knowledge to an understanding of the diseases and their impact on patients' lives, improving the targeting of public health efforts.

[Angioedema and anaphylaxis, a family story]

Non-allergic angioedema has a worrying morbidity. Clinical examination is central, as C1-esterase inhibitor deficiency will not be documented in the acute phase. In the case of anaphylaxis that does not respond to adrenaline, an early diagnosis can optimise referral of the patient to a reference healthcare establishment for a specific therapeutic protocol (icatibant, C1 inhibitor) recently updated by recommendations.

Hereditary angio-oedema with C1 inhibitor deficiency type I, an unusual stroke mimic

Hereditary angio-oedema with C1 inhibitor deficiency (C1-INH-HAE) type I is a rare immune disorder characterised by a deficit of functional C1 esterase inhibitor (C1-INH). Recurrent C1-INH-HAE attacks typically present as generalised skin swelling and abdominal pain. Neurological involvement is very unusual, with a few reports of cephalea and recurrent dizziness. We describe a woman in her 30s diagnosed with C1-INH-HAE type I who was referred to the emergency department suffering from left hemisensory syndrome, with the initial suspicion of an ischaemic stroke. A few hours after hospital admission, she presented an acute attack of facial swelling and abdominal pain, receiving intravenous C1-INH concentrate with complete resolution of all symptoms, including neurological ones. A complete aetiological study ruled out a stroke. We pointed out that C1-INH-HAE attack can be an unusual stroke mimic that responds favourably to replacement therapy.