Hereditary Angioedema C1-inhibitor Research Articles

The Expanding Spectrum of Mutations in Hereditary Angioedema

The evolution in the knowledge of rare genetic diseases such as hereditary angioedema (HAE) has increased at a parallel pace with the development of new molecular tools. The deficiency of C1 inhibitor (C1-INH) has been recognized as the main cause of HAE (HAE-C1-INH) since the 1960s, but the discovery of the wide spectrum of mutations affecting the C1-INH gene (SERPING1) was possible only from the late 1980s, when Sanger sequencing became available and more accessible worldwide. Nevertheless, the involvement of other genes in HAE was discovered only in 2006 with the description of mutations in the F12 gene in patients with HAE and normal C1-INH. In the last 3 years, advanced next-generation sequencing techniques allowed the identification of mutations in 5 new genes being associated with HAE and normal C1-INH: ANGPT1 (angiopoietin-1), PLG (plasminogen), KNG1 (kininogen), MYOF (myoferlin), and HS3ST6 (heparan sulfate-glucosamine 3-O-sulfotransferase 6). The knowledge provided by the new era of genomic studies was pivotal in the discovery of mutations in new genes responsible for this complex pathogenesis. Genomics advances promise a better understanding of unknown mechanisms leading to HAE, the establishment of new molecular targets for novel therapeutic agents, and personalized treatment.

Hereditary angioedema: Epidemiology and burden of disease.

<title/> Hereditary angioedema (HAE) is a rare autosomal dominant genetic disorder characterized by swelling of subcutaneous, mucosal, and submucosal tissue without associated pruritus or wheals caused by a temporary localized increase in vascular permeability. Swelling attacks primarily affect the cutaneous tissue, abdominal viscera, genitals, or airways. <title/> Reports of the prevalence of HAE C1 inhibitor (C1-INH) deficiency varies widely, from 1:50,000 to 1:100,000. The prevalence of HAE normal C1-INH is unknown but is likely much lower than HAE C1-INH. Approximately one-third of patients with recurrent angioedema without wheals have HAE. <title/> The burden of disease for patients with HAE is substantial. Attacks are unpredictable with respect to frequency, severity, and the site that swells. Laryngeal attacks can be fatal if not treated promptly and appropriately. Feelings of stress, anxiety, and depression can trigger attacks, and begin a cycle of attacks that cause anxiety that, in turn, triggers further attacks. Despite full physical recovery between attacks, patients often experience continual emotional impairment and reduced quality of life (QoL). Absenteeism from work and presenteeism at work or educational activities for patients and caregivers increase stress and reduce productivity during and between attacks. Missed opportunities for career development are common. <title/> Significant advances have been made in the past decade to expand both acute and prophylactic treatment options for patients with HAE, lowering both the disease and treatment burden, and improving the QoL of patients with HAE.

The attack localizations in C1 inhibitor deficient hereditary angioedema patients

Background Hereditary angioedema (HAE) is a rare autosomal dominant inherited disease characterized by recurrent angioedema episodes and classified as HAE with C1-inhibitor (C1INH) deficiency (HAE-C1INH) and HAE with normal C1-inhibitor (HAE-nlC1INH). It may involve the face, larynx, upper airways, trunk, gastrointestinal system, genital area, and extremities. The angioedema attacks are disabling, and laryngeal edema can lead to asphyxiation and death if it is not treated successfully. We aim to investigate the association between the attack localizations and complement parameters of HAE C1INH patients.Methods Patients with HAE-C1INH from Ege University Faculty of Medicine were included. Patients with HAE-nl-C1INH were excluded from the study. Data on the clinical records were obtained retrospectively. Sociodemographic data, age at disease onset, annual attack frequencies, attack localizations, and complement parameters were recorded.Results One-hundred patients were in the study group. Fifty four percent of them were female. The majority of patients were HAE-C1INH type I (87%). The mean age at disease onset was 12.01 ±7.04 years. Plasma C4 levels were normal in eight patients (8.16%). The most frequently involved localizations were extremities (91%), gastrointestinal system (89%), and genital area (85%). Having a facial attack and erythema marginatum were both found to be correlated with the occurrence of laryngeal edema. Laryngeal edema was seen in 83.8% of the patients with erythema marginatum (P=0.010), and 75.9% of the patients with facial attacks (P&amp;lt;0.001).Conclusion The correlation between erythema marginatum and laryngeal edema was not reported in previous studies. Due to the unpredictable and fatal nature of the laryngeal attacks, all HAE patients and physicians should be alert of the occurrence and emergency treatment of laryngeal edema. We recommend that C4 alone should not be used to exclude the diagnosis of HAE-C1INH. The laboratory work-up should also include C1 inhibitor levels and C1INH function analysis.

Hereditary angioedema: Screening of first-degree blood relatives and earlier diagnosis.

Background: Hereditary angioedema (HAE) with C1 inhibitor (C1INH) deficiency is an inherited disease characterized by sudden, recurrent episodes of edema that involve the skin, gastrointestinal tract, respiratory tract, and other organs. Objective: Because it takes a long time from the first symptoms to diagnosis, we aimed to identify HAE in untested first-degree blood relatives among some of our patients with HAE in our outpatient clinic at Hospital Universitário Clementino Fraga (HUCFF), Federal University of Rio de Janeiro. Methods: Untested first-degree relatives of patients with HAE C1INH, even those who were asymptomatic, were identified and invited to participate. Those who agreed to participate answered a specific questionnaire and had a blood sample collected for complement testing. Results: Fifty untested first-degree relatives of 30 index patients with HAE C1INH were identified, and both groups were analyzed. The mean ± standard deviation (SD) age of the index patients group was 37.08 ± 16.56 years (range, 13-73 years), with a high frequency in women (n = 24 [80.0%]). Most of them had severe (n = 23 [76.7%]) and moderate (n = 7 [23.3%]) attacks. None were asymptomatic. The mean ± SD time between the first symptoms and diagnosis was 20.2 ± 11.06 years (range, 0-48 years) in that group. In the first-degree relatives group, 30 new cases of HAE C1INH (60%) were identified. Conclusion: We found that there was a long time between early manifestations and a diagnosis of HAE. First-degree relatives of patients with HAE patients are at risk for having the disease. Sixty percent were newly diagnosed with HAE and with C1INH deficiency in our study. So, screening of family members, including individuals who were asymptomatic, is the key for earlier diagnosis and effective treatment.