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.

Phenotypes Determined by Cluster Analysis in Moderate to Severe Bronchial Asthma.

BACKGROUND: Bronchial asthma is a heterogeneous disease that includes various subtypes. They may share similar clinical characteristics, but probably have different pathological mechanisms. AIM: To identify phenotypes using cluster analysis in moderate to severe bronchial asthma and to compare differences in clinical, physiological, immunological and inflammatory data between the clusters. PATIENTS AND METHODS: Forty adult patients with moderate to severe bronchial asthma out of exacerbation were included. All underwent clinical assessment, anthropometric measurements, skin prick testing, standard spirometry and measurement fraction of exhaled nitric oxide. Blood eosinophilic count, serum total IgE and periostin levels were determined. Two-step cluster approach, hierarchical clustering method and k-mean analysis were used for identification of the clusters. RESULTS: We have identified four clusters. Cluster 1 (n=14) - late-onset, non-atopic asthma with impaired lung function, Cluster 2 (n=13) - late-onset, atopic asthma, Cluster 3 (n=6) - late-onset, aspirin sensitivity, eosinophilic asthma, and Cluster 4 (n=7) - early-onset, atopic asthma. CONCLUSIONS: Our study is the first in Bulgaria in which cluster analysis is applied to asthmatic patients. We identified four clusters. The variables with greatest force for differentiation in our study were: age of asthma onset, duration of diseases, atopy, smoking, blood eosinophils, nonsteroidal anti-inflammatory drugs hypersensitivity, baseline FEV1/FVC and symptoms severity. Our results support the concept of heterogeneity of bronchial asthma and demonstrate that cluster analysis can be an useful tool for phenotyping of disease and personalized approach to the treatment of patients.

Effect of micronized cellulose powder on the efficacy of topical oxymetazoline in allergic rhinitis.

BACKGROUND: Defective nasal barrier function is implicated in allergic rhinitis, which results in persistent inflammation and clinical symptoms, among which congestion plays a prominent role. In searching ways to improve the efficacy of nasally applied drugs in this condition, we tested the hypothesis that hydroxypropylmethylcellulose (HPMC), known as a mucoprotective agent, could enhance the efficacy of a decongestant (oxymetazoline nasal spray, 0.05%) by "sealing" it to the mucosa. METHODS: This double-blind placebo-controlled study was conducted with 40 patients (mean age, 35 years; 23 women) with persistent allergic rhinitis. The patients were randomized to receive 1 puff of oxymetazoline, followed by 1 puff of either HPMC or lactose powder (placebo) twice a day for 7 days and then only oxymetazoline rescue medication for another week. Peak inspiratory nasal flow (PNIF) was measured for 360 minutes after oxymetazoline and HPMC or placebo insufflation on days 1 and 8, and at a single point on day 15. Symptoms assessments involve visual analog scales and total nasal symptom scores. RESULTS: HPMC significantly enhanced oxymetazoline-increased PNIF at days 1 (p = 0.042) and 8 (p = 0.006). Baseline PNIF was greater in the HPMC group at day 15 (p = 0.014), indicative of further reduced nasal congestion. All nasal symptoms improved in both groups at day 8, but only the HPMC group showed further amelioration at day 15. Rescue medication was smaller in the HPMC group between days 8 and 15. CONCLUSION: HPMC enhances decongestion through mucoadhesion but may also be augmenting the mucosal barrier in allergic rhinitis, which explains the carryover efficacy of oxymetazoline for a week after its discontinuation. CLINICAL TRIAL REGISTRATION: clinicaltrials.gov identifier: NCT01986582.

Advent of oral medications for the treatment of hereditary angioedema.

BACKGROUND: Hereditary angioedema (HAE) is a rare genetic disorder characterized by unpredictable, debilitating episodes of submucosal and/or subcutaneous tissue swelling, which may be life-threatening depending on anatomic location. The two primary management strategies for HAE are ready access to effective on-demand treatment in all patients and the prevention of attacks (short-term prophylaxis [STP] and long-term prophylaxis [LTP]) in appropriate patients. All approved on-demand and most LTP medications require subcutaneous or intravenous administration. Injection-related challenges include trypanophobia (fear of needles), difficulty with self-administration, injection-site reactions (e.g., pain, erythema, bleeding, bruising), and anxiety-all contributing to poor compliance and administration delays. Oral HAE treatments may improve outcomes by reducing treatment barriers. AIM: To review oral therapies, approved or in development, for on-demand treatment and/or prevention of HAE attacks. MATERIALS AND METHODS: To provide a comprehensive review, data was obtained from publicly available resources through a targeted PubMed literature review and supplemented by information provided on company websites (search cutoff of May 31, 2024). RESULTS: Berotralstat, an oral plasma kallikrein (PKa) inhibitor, is approved for LTP. Sebetralstat, another PKa inhibitor, is the investigational first oral on-demand HAE treatment to complete a phase 3 trial. Deucrictibant, an oral bradykinin B2 receptor antagonist, has completed phase 2 trials for on-demand therapy and LTP. Several other oral PKa inhibitors (ATN249, VE-4666, and VE-4062) are in early development for LTP. CONCLUSION: Substantial advances have been made in the development of oral treatments for HAE. These treatments have the potential to improve and optimize clinical outcomes, satisfaction, and quality of life among patients with HAE.

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.

A Review of Randomized Controlled Trials of Hereditary Angioedema Long-Term Prophylaxis with C1 Inhibitor Replacement Therapy: Alleviation of Disease Symptoms Is Achievable.

Through its fluctuating disease activity and unpredictable attacks, hereditary angioedema (HAE) imposes a substantial patient burden. To minimize HAE burden and improve quality of life, treatment should involve individualized management strategies that address on-demand therapy and short-term/long-term prophylaxis. Goals of long-term prophylaxis include reducing the number, severity, and burden of HAE attacks. The best characterized forms of HAE arise from deficiency or dysfunction of C1-inhibitor (C1-INH; types I/II), and C1-INH replacement therapy is a first-line intervention for on-demand (acute) treatment of HAE attacks, short-term prophylaxis before high-risk procedures, and long-term prophylaxis. Randomized, double-blind, placebo-controlled crossover trials have shown dose-dependent efficacy with plasma-derived C1-INH (pdC1-INH) 40-60 IU/kg subcutaneously, pdC1-INH 1000 U intravenously, and recombinant human C1-INH (rhC1-INH) 50 IU/kg (maximum 4200 IU) intravenously, all administered twice weekly, as long-term prophylaxis in patients with a history of 2 to ≥4 attacks/month. Overall, up to 83% (pdC1-INH 60 IU/kg) of patients experienced an HAE attack reduction threshold of ≥70%, and up to 58% (pdC1-INH 60 IU/kg) achieved an attack reduction threshold of ≥90%. Lower-dose intravenous pdC1-INH therapy (1000 U) was seemingly less effective, with 45% of 22 patients experiencing an HAE attack reduction threshold of ≥70%, and up to 23% achieving an attack reduction threshold of ≥90%. Higher-dose intravenous rhC1-INH 50 IU/kg (maximum, 4200 IU) twice weekly was of intermediate benefit. Despite a baseline mean attack frequency of 17.9 (during the 3 months prior to study treatment) and a mean attack frequency during a 4-week placebo period of 7.2, 52% of 23 patients experienced ≥70% reduction in attack frequency and 26% of 23 patients experienced ≥90% reduction in attack frequency. The increasing patient percentages treated with C1-INH replacement therapy as long-term prophylaxis meeting these high thresholds reinforces hopes and expectations that "attack freedom" is achievable, including for those with moderate or severe disease.

Treatment of hereditary angioedema-single or multiple pathways to the rescue.

Hereditary angioedema (HAE) is a rare disease caused by mutations in the SERPING1 gene. This results in deficient or dysfunctional C1 esterase inhibitor (C1-INH) and affects multiple proteases involved in the complement, contact-system, coagulation, and fibrinolytic pathways. Current options for the treatment and prevention of HAE attacks include treating all affected pathways via direct C1-INH replacement therapy; or specifically targeting components of the contact activation system, in particular by blocking the bradykinin B2 receptor (B2R) or inhibiting plasma kallikrein, to prevent bradykinin generation. Intravenously administered plasma-derived C1-INH (pdC1-INH) and recombinant human C1-INH have demonstrated efficacy and safety for treatment of HAE attacks, although time to onset of symptom relief varied among trials, specific agents, and dosing regimens. Data from retrospective and observational analyses support that short-term prophylaxis with intravenous C1-INH products can help prevent HAE attacks in patients undergoing medical or dental procedures. Long-term prophylaxis with intravenous or subcutaneous pdC1-INH significantly decreased the HAE attack rate vs. placebo, although breakthrough attacks were observed. Pathway-specific therapies for the management of HAE include the B2R antagonist icatibant and plasma kallikrein inhibitors ecallantide, lanadelumab, and berotralstat. Icatibant, administered for treatment of angioedema attacks, reduced B2R-mediated vascular permeability and, compared with placebo, reduced the time to initial symptom improvement. Plasma kallikrein inhibitors, such as ecallantide, block the binding site of kallikrein to prevent cleavage of high molecular weight kininogen and subsequent bradykinin generation. Ecallantide was shown to be efficacious for HAE attacks and is licensed for this indication in the United States, but the labeling recommends that only health care providers administer treatment because of the risk of anaphylaxis. In addition to C1-INH replacement therapy, the plasma kallikrein inhibitors lanadelumab and berotralstat are recommended as first-line options for long-term prophylaxis and have demonstrated marked reductions in HAE attack rates. Investigational therapies, including the activated factor XII inhibitor garadacimab and an antisense oligonucleotide targeting plasma prekallikrein messenger RNA (donidalorsen), have shown promise as long-term prophylaxis. Given the requirement of lifelong management for HAE, further research is needed to determine how best to individualize optimal treatments for each patient.

Safety Aspects and Rational Use of Lanadelumab Injections in the Treatment of Hereditary Angioedema (HAE): Clinical Insights.

Hereditary angioedema (HAE) is a rare genetic disorder characterized by recurrent episodes of skin/mucosal swelling, and/or attacks of severe abdominal pain when it affects the gastrointestinal tract. The disease might be unexpectedly fatal when the upper airways are compromised. HAE clinical presentation, disease course and prognosis are associated with significant disease burden and severely impaired quality of life. Lanadelumab is a breakthrough therapy for the prevention of attacks in HAE type 1 and 2 patients. This revolutionary approach to administer a single subcutaneous injection (once every two to four weeks) and achieve complete disease control has dramatically improved patient care resulting in significant change in the life of affected families. Current data support the drug's tolerability in adult and adolescent patients without notable safety concerns in both clinical research and real-world settings. Rational use of prophylactic treatments of HAE searches for a socio-economic balance, taking into account the life-long course of the disease, the public health funds who pay the monetary price, and the patients who might need to receive the therapy for a period longer than investigated during the development program. In this review, we address the current evidence on lanadelumab's tolerability, highlighting aspects of the drug's rationale use in clinical practice. Further studies need to investigate whether this therapy might be appropriate in other forms of angioedema, such as idiopathic primary angioedema and HAE with normal C1 inhibitor. Future efforts must focus to improve modern drugs' accessibility in more countries. Although modern prophylactic options lessen the risk of fatal laryngeal attacks, patients must be equipped with reliable on-demand therapies and be trained how to use them as such a risk cannot be fully diminished with potentially life-threatening attacks occurring even in subjects with successful and stable long-term prophylaxis. Notwithstanding, further studies are needed to identify early responders from non-responders and develop therapies for the latter.

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.

Therapeutic management of hereditary angioedema: past, present, and future.

Hereditary angioedema is a rare disease that can often be disabling or even life threatening because of the unpredictable, self-limiting, and localized swelling episodes involving cutaneous, subcutaneous, and mucosal sites. The last decades revealed a spectrum of possibilities to control the disease through the development of effective therapies that changed the life of many patients and families worldwide. This review summarizes the current literature regarding the general management and therapeutic approach in patients with hereditary angioedema, both with and without C1 inhibitor deficiency. Medications already available in the market and new drugs in different research stages of development are addressed. Recent decades saw a huge leap in identifying mechanisms of angioedema and developing modern safe and effective medications to both treat acute angioedema manifestations and control disease activity via prophylactic therapy. Further improvement is still needed, together with improving global accessibility of diagnostic tools and effective medications. Whether novel drugs will demonstrate a sustained cost/effectiveness ratio will be answered in the years to come when we will witness whether a majority of the patients will benefit from these major advances.

Recombinant human C1 esterase inhibitor for hereditary angioedema attacks: A European registry.

BACKGROUND: Hereditary angioedema (HAE) due to C1 esterase inhibitor deficiency (C1-INH-HAE) is characterized by recurrent swelling attacks. A European treatment registry was established to review the adverse event profile and efficacy of recombinant human C1 esterase inhibitor (rhC1-INH) for HAE attacks. METHODS: Individuals with C1-INH-HAE were enrolled following a decision to treat with rhC1-INH and provision of written informed consent. Medical history and baseline HAE information were collected at screening. Healthcare providers entered data on HAE attacks, response to treatment, and adverse events using a web-based questionnaire. RESULTS: From July 1, 2011, through December 1, 2019, 71 patients with C1-INH-HAE (30 male/41 female; mean age, 47.3 years; age range, 19-78 years) in 9 countries reported 2356 attacks and were treated with rhC1-INH. Before registry entry, patients, including 20 (28.2%) who were on maintenance therapy/prophylaxis at registry enrollment, experienced a mean of 25 HAE attacks per year (median, 16 [range, 0-185]). Most treated HAE attacks were abdominal (46.1%), followed by peripheral (38.3%), oro-facial-pharyngeal (14.8%), urogenital (3.2%), and laryngeal (2.6%). The mean rhC1-INH dose was 3307 U (43.3 U/kg). Patients reported symptom improvement within 4 h for 97.8% of attacks (2305/2356) with rhC1-INH; most attacks (99.8%; 2351/2356) required only 1 dose. Five attacks were treated with a second dose (total rhC1-INH dose administered for attack, 4200 U). No hypersensitivity, thrombotic/thromboembolic events, or drug-related serious adverse events were reported. CONCLUSION: The rhC1-INH treatment registry provided real-world data on the treatment of 2356 HAE attacks that were consistent with clinical trial data of rhC1-INH in patients with C1-INH-HAE.

Lanadelumab Injection Treatment For The Prevention Of Hereditary Angioedema (HAE): Design, Development And Place In Therapy.

Despite the efficacy of the on-demand treatment for the control of acute attacks of Hereditary Angioedema due to C1-Inhibitor Deficiency (C1-INH-HAE), the number and severity of attacks and the impairment in the quality of life of the affected patients have led to the development of a new monoclonal antibody, lanadelumab, directly addressed to the blockage of bradykinin, the principal mediator of vasodilation during angioedema attacks. It is indicated for the prophylactic treatment, it is easy to administer, highly effective and with known limited side effects. The current review summarizes the development of the drug, its clinical background and its perspectives.

Lanadelumab for the prevention of attacks in hereditary angioedema.

Introduction: Hereditary angioedema (HAE) with C1 esterase inhibitor deficiency (C1-INH-HAE) is a rare disease that manifests with cutaneous and/or submucosal swellings due to uncontrolled activation of the contact/kinin system. Attacks recur with unpredictable frequency and severity, laryngeal edema is potentially lethal, and the disease burden may severely disrupt patients' lives.Areas covered: This review provides an overview of lanadelumab, a human monoclonal antibody targeted against plasma kallikrein that was recently approved for prevention of symptoms in C1-INH-HAE.Expert opinion: The phase III HELP Study demonstrated the efficacy of lanadelumab in reducing HAE attacks. These positive results are being further confirmed in the open-label extension study. This agent addresses some of the limitations of existing prophylactic options as tolerability issues, the need for intravenous administration and frequent dosing. Therefore, lanadelumab can profoundly improve the quality of life of patients with C1-INH-HAE.

Current and emerging biologics for the treatment of hereditary angioedema.

INTRODUCTION: Hereditary angioedema due to C1-INH deficiency (C1-INH-HAE) is a rare disease with unpredictable, self-limiting and localized swelling episodes involving the cutaneous and subcutaneous tissues. In the last decade, the spectrum of the possibilities to control the disease has considerably changed with the development of biologic therapies making necessary a careful evaluation of the differences among current and emerging treatments to properly optimize the management of patients. AREAS COVERED: This review serves to summarize the literature regarding the use of biologics for the treatment of C1-INH-HAE. Medications already available on the market and new drugs in different phases of development are addressed. EXPERT OPINION: The advent of biologic therapies dramatically improved the lives of patients with C1-INH-HAE although further improvement is still needed. Whether this is cost/effective will be answered in the next years when we will see if these major advances will benefit the majority of the patients.

Recombinant human C1 esterase inhibitor (Conestat alfa) for prophylaxis to prevent attacks in adult and adolescent patients with hereditary angioedema.

INTRODUCTION: Hereditary angioedema (HAE) due to C1 inhibitor (C1-INH) deficiency is a debilitating and potentially lethal disease. Management includes on-demand treatment of angioedema and their prophylaxis. Plasma derived C1-INH is an established treatment for both on demand and prophylaxis of HAE. Conestat alfa is a recombinant form of human C1-INH (rhC1-INH) produced in transgenic rabbits. It has granted drug's registration as treatment option for acute HAE attacks in adults and adolescents in Europe, America, and other countries. Long-term prophylaxis with rhC1-INH received recent consideration in clinical trials. Areas covered: This review will critically appraise available information about rhC1-INH (conestat alfa) prophylactic treatment in adult and adolescent patients with congenital C1-INH deficiency. Results from a phase II randomized placebo-controlled trial for prophylaxis of severe HAE evidenced positive treatment outcomes for its application, both twice or once weekly. Expert commentary: Phase II clinical studies suggest that rhC1-INH is a viable option for prophylaxis of HAE. Safety and tolerability data are comparable to other available HAE specific drugs, zeroing the possibility for blood-born viral transmission. Sustainability of modern technologies is granting a practically stable and continuous recombinant production process. With other available options, rhC1-INH facilitates tailoring HAE treatment to patients' needs.

The physician and hereditary angioedema friend or foe: 62-year diagnostic delay and iatrogenic procedures.

BACKGROUND: Hereditary angioedema due to C1 inhibitor deficiency (C1-INH-HAE) is a rare autosomal dominant disease characterized by episodes of acute subcutaneous swelling, and/or recurrent severe abdominal pain. The disease is potentially fatal if the upper-airway is involved. Iatrogenic harm can occur if HAE is not considered in the differential diagnosis, the specialists are not aware of the natural history, diagnosis and treatment of HAE, or as a result of unnecessary surgical and other iatrogenic interventions. CASE PRESENTATION: We present the case of a 72-year-old man who began suffering recurrent abdominal pain at the age of 8 years. The pain led to frequent emergency department visits, three emergency surgical interventions, and 5 endoscopies before C1-INH-HAE was diagnosed at the age of 70. Infrequent subcutaneous swellings were attributed to unknown allergic reactions that were not related to the primary diagnosis of abdominal pain. Family history was positive for recurrent abdominal pain and angioedema but was ignored until the propositus' grandson developed recurrent severe oro-facial edema attacks. The boy's mother searched the worldwide web and found educational materials on a patient association website. She suggested complement C4 and C1-INH testing that led to the appropriate diagnosis of C1-INH-HAE type 1 in her son and his grandfather. CONCLUSION: This report emphasizes the importance of accurately evaluating personal and family history in patients with a long history of recurrent, acute, severe but medically unexplained abdominal pain and cutaneous swellings. Here, the diagnosis of HAE was overlooked for 62 years and the focus on abdominal complaints led to numerous surgical interventions without consideration of the full differential diagnosis. Screening family members from all generations for unrecognized angioedema, abdominal pain, and measurement of C1-INH and C4 are essential for accurate and timely diagnosis of HAE.

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.