A Core Outcome Set for Efficacy of Acute Treatment of Hereditary Angioedema.

BACKGROUND: Clinical trials investigating drugs for the acute treatment of hereditary angioedema attacks have assessed many different outcomes. This heterogeneity limits the comparability of trial results and may lead to selective outcome reporting bias and a high burden on trial participants. OBJECTIVE: To achieve consensus on a core outcome set composed of key outcomes that ideally should be used in all clinical efficacy trials involving the acute treatment of hereditary angioedema attacks. METHODS: We conducted a Delphi consensus study involving all relevant parties: patients with hereditary angioedema, hereditary angioedema expert clinicians and clinical researchers, pharmaceutical companies, and regulatory bodies. Two Internet-based survey rounds were conducted. In round 1, panelists indicated the importance of individual outcomes used in clinical trials on a 9-point Likert scale. Based on these results, a core outcome set was developed and voted on by panelists in round 2. RESULTS: A total of 58 worldwide panelists completed both rounds. The first round demonstrated high importance scores and substantial agreement among the panelists. In the second round, a consensus of 90% or greater was achieved on a core outcome set consisting of five key outcomes: change in overall symptom severity at one predetermined time point between 15 minutes and 4 hours after treatment, time to end of progression of all symptoms, the need for rescue medication during the entire attack, impairment of daily activities, and treatment satisfaction. CONCLUSIONS: This international study obtained a high level of consensus on a core outcome set for the acute treatment of hereditary angioedema attacks, consisting of five key outcomes.

Modulation of the Mas-Related G Protein-Coupled Receptor X2 (MRGPRX2) by Xenobiotic Compounds and Its Relevance to Human Diseases.

Mast cells (MCs) are immune cells that reside in tissues; particularly in the skin, and in the gastrointestinal and respiratory tracts. In recent years, there has been considerable interest in the Mas-Related G Protein-Coupled Receptor X2 (MRGPRX2), which is present on the surface of MCs and can be targeted by multiple exogenous and endogenous ligands. It is potentially implicated in non-IgE-mediated pseudoallergic reactions and inflammatory conditions such as asthma or atopic dermatitis. In this paper, we review natural products and herbal medicines that may potentially interact with MRGPRX2. They mainly belong to the classes of polyphenols, flavonoids, coumarins, and alkaloids. Representative compounds include rosmarinic acid, liquiritin from licorice extract, osthole, and sinomenine, respectively. While evidence-based medicine studies are still required, these compounds have shown diverse effects, such as antioxidant, analgesic, anti-inflammatory, or neuroprotective. However, despite potential beneficial effects, their use is also burdened with risks of fatal reactions such as anaphylaxis. The role of MRGPRX2 in these reactions is a subject of debate. This review explores the literature on xenobiotic compounds from herbal medicines that have been shown to act as MRGPRX2 ligands, and their potential clinical significance.

High burden of clonal mast cell disorders and hereditary α-tryptasemia in patients who need Hymenoptera venom immunotherapy.

BACKGROUND: In patients who require venom immunotherapy (VIT), there is a need to identify underlying mast cell (MC) disorders since these may affect the risk and severity of future sting reactions and the long-term effectiveness of VIT. METHODS: 1319 individuals with Hymenoptera venom allergy (HVA) who needed VIT from referral centers in Slovenia, Austria, Croatia, and Poland underwent examination for KIT p.D816V in peripheral blood leukocytes (PBL) using a highly sensitive PCR test and tryptase genotyping by digital droplet PCR. We also included 183 control individuals with large local reactions (LLRs) to Hymenoptera stings and with asymptomatic sensitization to Hymenoptera venoms. RESULTS: 285 of 1319 individuals recommended for VIT (21.6%) were positive for KIT p.D816V in PBL, preferably those who present with severe reaction (33.9% [n = 207 of 610] with Ring-Messmer grade 3-4 vs. 11% [n = 78 of 709] with Grade 1-2; p < .0001), whereas only 1.3% (n = 2 of 152) of controls with LLR and none with asymptomatic sensitization (n = 31) had KIT p.D816V. KIT p.D816V allelic burden was higher in those with severe reaction (median 0.018% [n = 207] in Grade 3-4 vs. 0.001% [n = 78] in Grade 1-2; p < .0001), and the majority had normal baseline serum tryptase levels (69% [n = 196 of 285]). All KIT p.D816V-positive individuals (n = 41) who underwent bone marrow (BM) biopsy were found to have underlying clonal diseases, principally BM mastocytosis. HαT was also associated with severe HVA and symptoms (p < .01), and remarkably, 31.0% (n = 31 of 100) were found to have concomitant KIT p.D816V. Concomitant HαT and KIT p.D816V showed an additive effect, and having both was associated with the highest risk for severe HVA, even higher than having either HαT or KIT p.D816V alone (OR = 3.8; p < .01). CONCLUSIONS: By employing prospective universal tryptase genotyping and examination for KIT p.D816V in PBL in large HVA populations, we have demonstrated a high burden of clonal MC disorders and HαT in patients who require VIT.

Clinical Characteristics and Quality of Life in a Cohort of Polish Pediatric Patients with Hereditary Angioedema.

Hereditary angioedema (HAE) is a rare genetic disease. It is characterized by recurrent attacks of angioedema. Evidence to what extent it affects patient functioning is limited in the pediatric population. We aimed to determine the clinical characteristics and management of Polish children with HAE and to measure the health-related quality of life (HRQoL) of these patients. This cross-sectional study was conducted among 21 pediatric patients and their caregivers, as well as 21 respective controls randomly selected from the general population. During routine follow-up visits, standardized pediatric quality of life questionnaires (PedsQLTM 4.0) were administered to all caregivers and adolescents (≥13 years). Caregivers also completed a structured medical interview regarding the clinical characteristics and treatment of children with HAE during the previous six months. During this period, 57% of patients had low (group I), 24% moderate (group II), and 19% high (group III) HAE activity, corresponding to ≥10 attacks per 6 months. None of the patients received long-term prophylaxis. The children in group III had a lower HRQoL than other groups and controls on all dimensions of the PedsQLTM 4.0. The lowest scores in all groups were observed in the emotional functioning domain. Our data demonstrate that the burden of HAE on the quality of life of pediatric patients and their families encompasses a wide range of daily functioning.

Diagnostic Value of Oral Provocation Tests in Drug Hypersensitivity Reactions Induced by Nonsteroidal Anti-Inflammatory Drugs and Paracetamol.

Oral drug provocation tests (DPT) are the basic diagnostic tool for the detection of hypersensitivity to non-opioid analgesics and for selecting a safe alternative for a patient. They are of great practical importance due to their common use, but the data on the follow-up of patients after negative DPT are still very scarce. We examined the further fate of 164 such adult patients after negative NSAID or paracetamol tests and analyzed which excipients in the studied drugs they could be exposed to after the diagnostic workup. A structured medical interview was performed 32.9 months (mean) after the provocation tests. Of the 164 patients, 131 (79.9%) retook the tested drug and 12 developed another hypersensitivity reaction, giving the estimated negative predictive value of 90.8%. These reactions were induced by acetylsalicylic acid, paracetamol, meloxicam, and diclofenac, and were clinically similar to the initial ones (most commonly urticaria and angioedema). There are 93 generics of these drugs on the local market, containing a total of 33 excipients for which hypersensitivity reactions have been reported. All available generics contain such excipients. Thirty-one patients (20.1%) did not take the previously tested drug again, most often because it was not needed or because they were afraid of another reaction. DPT with analgesics has a high diagnostic performance. A minority of patients had relapsed after reexposure. One of the underestimated reasons for this may be drug excipients provoking a reaction, so it is advisable to use exactly the same medical product that has been negatively tested. Many patients avoid reexposure to a given drug, despite negative tests, therefore very reliable patient education in connection with DPT is highly needed.

Searching for Genetic Biomarkers for Hereditary Angioedema Due to C1-Inhibitor Deficiency (C1-INH-HAE).

Existing evidence indicates that modifier genes could change the phenotypic outcome of the causal SERPING1 variant and thus explain the expression variability of hereditary angioedema due to C1-inhibitor deficiency (C1-INH-HAE). To further examine this hypothesis, we investigated the presence or absence of 18 functional variants of genes encoding proteins involved in the metabolism and function of bradykinin, the main mediator of C1-INH-HAE attacks, in relation to three distinct phenotypic traits of patients with C1-INH-HAE, i.e., the age at disease onset, the need for long-term prophylaxis (LTP), and the severity of the disease. Genetic analyses were performed by a validated next-generation sequencing platform. In total, 233 patients with C1-INH-HAE from 144 unrelated families from five European countries were enrolled in the study. Already described correlations between five common functional variants [F12-rs1801020, KLKB1-rs3733402, CPN1-rs61751507, and two in SERPING1 (rs4926 and rs28362944)] and C1-INH-HAE severity were confirmed. Furthermore, significant correlations were found between either the age at disease onset, the LTP, or the severity score of the disease and a series of other functional variants (F13B-rs6003, PLAU-rs2227564, SERPINA1-rs28929474, SERPINA1-rs17580, KLK1-rs5515, SERPINE1-rs6092, and F2-rs1799963). Interestingly, correlations uncovered in the entire cohort of patients were different from those discovered in the cohort of patients carrying missense causal SERPING1 variants. Our findings indicate that variants other than the SERPING1 causal variants act as independent modifiers of C1-INH-HAE severity and could be tested as possible prognostic biomarkers.

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.

In Vitro Assays for Diagnosis of Drug-Induced Nonsevere Exanthemas: A Systematic Review and Meta-Analysis.

Frequent mislabelled causal relationship between drug hypersensitivity reactions and culprit drugs reinforces the need for an accurate diagnosis. The systematic reviews and meta-analyses of in vitro assays published so far focused on immediate reactions and the most severe delayed reactions, while the most frequent drug-induced delayed reactions-nonsevere exanthemas-have been underestimated. We aim to fill this gap. A systematic review of studies on in vitro assays used in the diagnosis of nonsevere drug-induced delayed reactions was conducted following the methodology of Preferred Reporting Items for a Systematic Review and Meta-analysis of Diagnostic Test Accuracy Studies Statement. The EMBASE and PubMed databases were searched. We have included 33 studies from which we extracted the data, then performed meta-analysis where possible, or synthesised the evidence narratively. The quality of the analysed studies was assessed with the QUADAS-2 tool. The tests identified the most frequently were lymphocyte transformation test (LTT), ELISpot, and ELISA. In the meta-analysis carried out for LTT in reactions induce by beta-lactams, the pool estimate of sensitivity and specificity amounted to 49.1% (95% CI: 14.0%, 85.0%) and 94.6% (95% CI: 81.7%, 98.6%), respectively. The studies showed heterogeneity in study design and laboratory settings, which resulted in a wide range of specificity and sensitivity of testing.

Clinical Characteristics and Management of Angioedema Attacks in Polish Adult Patients with Hereditary Angioedema Due to C1-Inhibitor Deficiency.

Hereditary angioedema (HAE) due to C1-inhibitor (C1-INH) deficiency is a rare disease characterized by recurrent swellings. This study aims to determine (i) the clinical characteristics of the HAE patient population from Poland, and (ii) real-life patients' treatment practices. A cross-sectional study involved 138 adult HAE patients (88 females, 50 males) treated in six regional HAE centers in Poland. Consecutive patients during routine follow-up visits underwent a structured medical interview on the clinical characteristics of the course and treatment of HAE attacks within the last six months. A total of 118 of 138 patients was symptomatic. They reported in total 2835 HAE attacks predominantly peripheral and abdominal, treated with plasma-derived C1-INH (61.4%), icatibant (36.7%) and recombinant C1-INH (1.9%). An amount of 116 patients carried the rescue medication with them while traveling, and 74 patients self-administrated on demand treatment. There were twice as many symptomatic women (n = 78) as there were men (n = 40). Women treated their HAE attacks significantly more often than men. Older patients (≥65 years) reported a longer delay in diagnosis, and practiced the self-administration of rescue medication less frequently in comparison to other patients. Clinical features of the surveyed population are similar to other European, but not Asian, HAE patient groups. Self-administration still remains an unmet medical need. Some distinct HAE patients may require special attention due to the severe course of the disease (females) or a delay in diagnosis (the elderly).

Alpha-gal syndrome: the first report in Poland.

Alpha-gal syndrome is an immunoglobulin E (IgE)-dependent allergy to galactose-α-1,3-galactose, resulting in a delayed anaphylactic reaction to red meat. The syndrome is causally linked to bites from ticks and associated with cross-reactivity to some drugs, e.g. cetuximab. Although cases of alpha-gal allergy have already been reported in a few European countries, to our best knowledge, no cases have been reported so far in Central-Eastern Europe. In the current report, we describe a case of alpha-gal syndrome diagnosed in Poland, to highlight the fact that it may occur in new geographic areas. Within three months, the described patient underwent five anaphylactic reactions with typical clinical manifestations. They developed a few hours after ingestion of red meat (pork, beef or mutton) and were preceded by tick bites. The level of specific IgE antibodies to alpha-gal reached 72.6 kAU/l, whereas the levels of specific IgE antibodies to other food allergens were within the reference range. As the onset of symptoms in this syndrome is usually delayed, numerous cases may be identified as idiopathic anaphylaxis, while early diagnosis is indispensable to avoid potentially life-threatening complications.

Risk Factors for Hepatotoxicity Due to Paracetamol Overdose in Adults.

Background and Objectives: Over-the-counter availability and a good safety profile make paracetamol one of the most common analgesics in developed countries but also the leading cause of liver failure due to overdose. The objectives of the study were to identify modifiable risk factors for severe hepatotoxicity following paracetamol overdose in adults. Materials and Methods: A retrospective cohort study involved the consecutive adult patients hospitalized in a toxicological center over a period of seven years due to paracetamol overdose. Complete medical datasets of laboratory and anamnestic variables were analyzed and validated by means of logistic regression model. Results: A total of 185 patients entered the study, including 25 individuals who developed severe hepatotoxicity (plasma aminotransferases levels above 1000 UI/L) and 31 individuals with mild to moderate liver injury (plasma aminotransferases levels above upper normal range, but below 1000 UI/L). In the univariable analysis, significant hepatotoxicity risk factors were male gender, alcohol abuse, an ingested paracetamol dose, and a timespan from ingestion to hospital admission. The later one was the only significant risk factor in the multivariable model (adjusted odds ratio 1.08; 95% CI: 1.03-1.12). Conclusions: A delay in hospital admission, resulting in a delayed administration of disease-specific treatment outweighs any other known risk factors of paracetamol-induced hepatotoxicity.

ELISpot assay as a diagnostic tool in drug hypersensitivity reactions.

In patients with drug hypersensitivity reactions, confirmation of causality frequently facilitates decision on a continuation or withdrawal of a given treatment. Unfortunately, identification of the culprit drug often proves difficult. In vivo methods possess well-known disadvantages like low sensitivity of skin tests or the risk of relapse during drug provocation tests. Therefore, laboratory assays are of great interest as they may improve causal diagnosis without putting patients at risk. In this article, the mechanistic principles and methodological issues of the enzyme-linked immunospot (ELISpot) assay were recapped the context of drug hypersensitivity reactions. A review of ELISpot application in causal diagnosis of drug hypersensitivity was based on literature search. The main findings are: (i) ELISpot assay has a good performance in the detection of drug-specific response. (ii) ELISpot results seem to be not substantially impacted by the type of drug or phenotype of the reaction. (iii) Testing within 30 days since the episode of drug hypersensitivity reaction shows a better performance than in later recovery phase. (iv) Data from pediatric population are too scarce to draw any conclusions. (v) Differences in laboratory protocols and in criteria used in the assessment of ELISpot plates along with the issue of the technical feasibility and reproducibility may limit the use of this assay in the routine diagnostic of drug hypersensitivity reactions.

Biomarkers in Hereditary Angioedema.

A biomarker is a defined characteristic measured as an indicator of normal, biologic, pathogenic processes, or biological responses to an exposure or intervention. Diagnostic biomarkers are used to detect a disease or a subtype of a disease; monitoring biomarkers are measured serially to assess a medical condition; response biomarkers are used to check biologic response following a medical intervention; predictive biomarkers are used to identify patients who are more likely to respond to a medical intervention; and prognostic biomarkers are used to assess the future likelihood of a clinical event. Although biomarkers have been extensively investigated and validated in many diseases and pathologies, very few are currently useful for the diagnosis, evaluation of disease activity, and treatment of hereditary angioedema (HAE). Pathophysiologic pathways involved in HAE reveal a plethora of molecules from the complement, coagulation, and fibrinolysis systems or from the vascular endothelium, which may serve as biomarkers. The most promising candidates, together with their laboratory readout systems, should be evaluated with regard to their analytical and clinical validity and utility. To be highly specific, such biomarkers should be linked to the pathomechanisms of HAE, particularly the bradykinin-generating cascade. Additionally, major advances in high-throughput omics-based technologies may facilitate the discovery of new candidate biomarkers in the future. This review will cover the existing as well as future potential biomarkers that will support the diagnosis, monitor disease activity, and can be used to assess the efficacy of new avenues of therapy of HAE and other forms of angioedema.

Angioedema. Interdisciplinary diagnostic and therapeutic recommendations of the Polish Dermatological Society (PTD) and Polish Society of Allergology (PTA).

Angioedema is a non-inflammatory oedema of the subcutaneous tissue and/or mucosal membranes. It most commonly coexists with urticaria wheals and is considered to be a deep form of urticaria. Less commonly, it occurs in isolation and can take two basic forms: acquired angioedema and hereditary angioedema. Currently, there are 4 defined types of acquired angioedema and 7 types of hereditary angioedema. Treatment of angioedema depends on its form and etiological factors. Especially the genetic form, i.e. hereditary angioedema, is a considerable challenge for medical specialists, particularly dermatologists and allergists.

Life-threatening laryngeal attacks in hereditary angioedema patients.

BACKGROUND: Hereditary angioedema due to C1-inhibitor deficiency (HAE-C1INH) is a rare genetic disease that runs in the family. As a result of the disease, acute swellings of the subcutaneous tissue and mucous membranes of the digestive and respiratory systems, including the larynx, occur. Any attack of the disease involving the throat and larynx is particularly dangerous and requires knowledge of clinical determinants of the disease and its proper management. MATERIALS AND METHODS: The study included adult consecutive HAE-C1INH patients having follow-up visits in our centre. The group was examined with a structured clinical questionnaire, concerning the last 6 months and focusing particularly on laryngeal swelling attacks. RESULTS: 55 subjects (F/M - 35/20, age range - 18-76) were included in the study. Laryngeal attacks occurred in 19 individuals (34.5%): 1-3, 4-6, and ≥7 attacks in 9, 8 and 2 patients, respectively, two of whom required intubation. In comparison to other patients, subjects with laryngeal attacks were characterised by significantly more frequent: (1) facial attacks, (2) severe disease activity, (3) the occurrence of female patients, (4) mental stress as a trigger of attacks. All patients with laryngeal attacks had a rescue medication at home and 15/19 (78%) patients could use it at home. Most of them used plasma-derived C1-inhibitor 17/19 (89.5%) and icatibant, 8/19 (42.1%). DISCUSSION: HAE-C1INH patients with laryngeal attacks require particular attention. Proper training regarding the identification of these patients, adequate management, access to emergency services and emergency drugs are essential to ensure the safety of subjects with this localization of HAE-C1INH attacks.

A novel deep intronic SERPING1 variant as a cause of hereditary angioedema due to C1-inhibitor deficiency.

BACKGROUND: In about 5% of patients with hereditary angioedema due to C1-inhibitor deficiency (C1-INH-HAE) no mutation in the SERPING1 gene is detected. METHODS: C1-INH-HAE cases with no mutation in the coding region of SERPING1 after conventional genotyping were examined for defects in the intronic or untranslated regions of the gene. Using a next-generation sequencing (NGS) platform targeting the entire SERPING1, 14 unrelated C1-INH-HAE patients with no detectable mutations in the coding region of the gene were sequenced. Detected variants with a global minor allele frequency lower than the frequency of C1-INH-HAE (0.002%), were submitted to in silico analysis using ten different bioinformatics tools. Pedigree analysis and examination of their pathogenic effect on the RNA level were performed for filtered in variants. RESULTS: In two unrelated patients, the novel mutation c.-22-155G > T was detected in intron 1 of the SERPING1 gene by the use NGS and confirmed by Sanger sequencing. All bioinformatics tools predicted that the variant causes a deleterious effect on the gene and pedigree analysis showed its co-segregation with the disease. Degradation of the mutated allele was demonstrated by the loss of heterozygosity on the cDNA level. According to the American College of Medical Genetics and Genomics 2015 guidelines the c.-22-155G > T was curated as pathogenic. CONCLUSIONS: For the first time, a deep intronic mutation that was detected by NGS in the SERPING1 gene, was proven pathogenic for C1-INH-HAE. Therefore, advanced DNA sequencing methods should be performed in cases of C1-INH-HAE where standard approaches fail to uncover the genetic alteration.

Hypersensitivity Reactions in Serious Adverse Events Reported for Paracetamol in the EudraVigilance Database, 2007⁻2018.

Paracetamol is a popular and easily available drug which is used world-wide as analgesic, antipyretic agent. Hypersensitivity reactions to this drug involve a wide range of symptoms of various importance for patient management. The EudraVigilance (EV) database serves as a system for monitoring adverse events (AE) due to drug intake. We retrospectively recorded AE reports for "paracetamol" reported from 1 January 2007 to 1 October 2018 which fulfilled the category of "serious" in EV. For further analysis the retrieved AE reports were selected according to the keywords corresponding to hypersensitivity symptoms. We included in the study 4589 AE reports with 9489 particular AEs. 24.2% of all the AE reports concerned children. The most often reported symptoms were "angioedema," "rash" and "urticaria" (each of them with a frequency of >10% in the AE reports). An important group of AEs were oedema reported as being located in the head, neck or respiratory tract. We recorded 58 AE reports with fatal outcomes, including 9 Stevens-Johnson syndrome/toxic epidermal necrolysis cases (SJS/TEN), 10 anaphylactic reactions, 21 cases of hepatic failure and a further 18 cases which occurred for other reasons. SJS/TEN, acute generalized exanthematous pustulosis and drug reaction with eosinophilia and systemic symptoms were reported 129, 42 and 25 times, respectively. Prodromes and symptoms of potentially life-threating SJS/TEN appeared in 286 of the AE reports. 380 AE reports pointed to a diagnosis of anaphylaxis. To improve patient safety, healthcare professionals, including pharmacists, can identify warning signs of severe hypersensitivity reactions to paracetamol.

Targeted next-generation sequencing for the molecular diagnosis of hereditary angioedema due to C1-inhibitor deficiency.

SERPING1 genotyping of subjects suspicious for hereditary angioedema due to C1-INH deficiency (C1-INH-HAE) is important for clinical practice as well as for research reasons. Conventional approaches towards the detection of C1-INH-HAE-associated SERPING1 variants are cumbersome and time-demanding with many pitfalls. To take advantage of the benefits of next-generation sequencing (NGS) technology, we developed and validated a custom NGS platform that, by targeting the entire SERPING1 gene, facilitates genetic testing of C1-INH-HAE patients in clinical practice. In total, 135 different C1-INH-HAE-associated SERPING1 variants, out of the approximately 450 reported, along with 115 negative controls and 95 randomly selected DNA samples from affected family members of C1-INH-HAE index patients, were included in the forward and reverse validation processes of this platform. Our platform's performance, i.e. analytical sensitivity of 98.96%, a false negative rate of 1.05%, analytical specificity 100%, a false positive rate equal to zero, accuracy of 99.35%, and repeatability of 100% recommends its implementation as a first line approach for the genetic testing of C1-INH-HAE patients or as a confirmatory method. A noteworthy advantage of our platform is the concomitant detection of single nucleotide variants and copy number variations throughout the whole length of the SERPING1 gene, moreover providing information about the size and the localization of the latter. During our study, 15 novel C1-INH-HAE-related SERPING1 variants were detected.