Mutation update of SERPING1 related to hereditary angioedema in the Chinese population

Complex analysis of the national Hereditary angioedema cohort in Slovakia - Identification of 12 novel variants in SERPING1 gene

Background

Hereditary angioedema (HAE) is a rare autosomal dominant genetic disease characterised by acute episodes of non-pruritic skin and submucosal swelling caused by increase in vascular permeability.

Objective

Here we present the first complex analysis of the National HAE Slovakian cohort with the detection of 12 previously un-published genetic variants in SERPING1 gene.

Methods

In patients diagnosed with hereditary angioedema caused by deficiency or dysfunction of C1 inhibitor (C1-INH-HAE) based on clinical manifestation and complement measurements, SERPING1 gene was tested by DNA sequencing (Sanger sequencing/massive parallel sequencing) and/or multiplex ligation-dependent probe amplification for detection of large rearrangements.

Results

The Slovakian national cohort consisted of 132 living patients with confirmed HAE. We identified 51 index cases (32 families, 19 sporadic patients/112 adults, 20 children). One hundred seventeen patients had HAE caused by deficiency of C1 inhibitor (C1-INH-HAE-1) and 15 patients had HAE caused by dysfunction of C1 inhibitor (C1-INH-HAE-2). The prevalence of HAE in Slovakia has recently been calculated to 1:41 280 which is higher than average calculated prevalence. The estimated incidence was 1:1360 000. Molecular-genetic testing of the SERPING1 gene found 22 unique causal variants in 26 index cases, including 12 previously undescribed and unreported.

Conclusion

The first complex report about epidemiology and genetics of the Slovakian national HAE cohort expands the knowledge of the C1-INH-HAE genetics. Twelve novel causal variants were present in the half of the index cases. A higher percentage of inframe variants comparing to other studies was observed. Heterozygous deletion of exon 3 found in a large C1-INH-HAE-1 family probably causes the dysregulation of the splicing isoforms balance and leads to the decrease of full-length C1-INH level.

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.

Altered Urinary Metabolomics in Hereditary Angioedema

Hereditary angioedema (HAE) is a rare and potentially life-threatening disease with heterogeneous clinical symptoms. The metabolomic profile of HAE remains unknown. Uncovering the metabolic signatures of HAE may provide inspiration for a comprehensive understanding of HAE pathogenesis and may help explore potential new metabolic biomarkers. We performed a comprehensive metabolic analysis using high-performance liquid chromatography−tandem mass spectrometry (HPLC-MS/MS). Urine samples from 34 HAE patients and 82 healthy controls (HCs) were collected to characterize the metabolic signatures associated with HAE. The metabolomes of HAE patients carrying different mutation types were also compared. A total of 795 metabolites were accurately detected and quantified. We considered 73 metabolites as differential metabolites in HAE patients (with an importance in projection (VIP) value > 1.0, q-value < 0.05, and fold change (FC) ≥ 1.2 or FC ≤ 0.8). Several metabolites associated with riboflavin metabolism, the citrate cycle, oxidative stress, and inflammation, including xanthine, oxypurinol, vitamin B2, and isocitrate, were significantly altered in HAE patients. No significantly different metabolites were found in HAE patients carrying different mutation types. The present study highlights that metabolic disturbances in the purine metabolism, riboflavin metabolism, and TCA cycle may be involved in the pathogenesis of HAE. Although biochemical significance requires further experimental verification, these findings may help to identify novel candidate metabolite biomarkers associated with HAE.