Gene Mutations Linked to Hereditary Angioedema in Solitary Angioedema Patients With Normal C1 Inhibitor.

BACKGROUND: Chronic recurrent angioedema without wheals (CRA) with normal C1 inhibitor (C1-INH) that is unresponsive to antihistamines may involve patients with recurrent angioedema of unknown cause (ie, so-called non-histaminergic idiopathic angioedema) as well as patients with hereditary angioedema with normal C1-INH (HAEnCI) when HAEnCI occurs in only one family member. OBJECTIVE: To identify patients with one of type of HAEnCI in a group of patients with CRA with normal C1-INH that was unresponsive to antihistamines. METHODS: A total of 132 patients with CRA and normal C1-INH that was unresponsive to antihistamines underwent mutational and clinical analysis. The presence of hereditary angioedema-specific mutations in Factor XII, plasminogen, ANGPT1, KNG1, MYOF, and HS3ST6 genes was tested by Sanger sequencing. When an HAEnCI-causing mutation was identified, available asymptomatic relatives were genetically tested. RESULTS: In 116 of 132 solitary patients with CRA (87.9%), none of the six HAEnCI-linked mutations could be found. Ten patients (7.6%) had the Factor XII mutation c.983C>A (p.T328K) and six (4.5%) the plasminogen mutation c.988A>G (p.K330E). Other mutations linked to HAEnCI were not found in this patient series. In the 16 families with HAEnCI, 11 asymptomatic carriers of one of the HAEnCI-linked mutations were identified. CONCLUSIONS: A search for HAEnCI-linked mutations in patients with solitary CRA may lead to the detection of patients and families with HAEnCI. This is important because family members can be identified who are at risk for developing potentially life-threatening angioedema, although they were previously asymptomatic. Without genetic investigation, the risk for an HAEnCI would have remained undetected in these patients and asymptomatic relatives.

Inheritance Pattern of Hereditary Angioedema Indicates Mutation-Dependent Selective Effects During Early Embryonic Development.

BACKGROUND: Hereditary angioedema (HAE) may be caused by a genetic deficiency of functional C1 inhibitor (C1-INH) or linked with mutations in the F12, PLG, and other genes in combination with normal C1-INH (HAEnCI). Although the types of hereditary angioedema due to deficiency of functional C1 inhibitor and HAEnCI are autosomal dominant inherited, there is the impression that in the types of HAEnCI more females carry disease-linked mutations. OBJECTIVE: The aim of this study was to analyze the passing on of the HAE-specific mutations to the next generations in families with various types of HAE. METHODS: Methods comprised pedigree analysis, Sanger sequencing analysis, biochemical analysis of parameters of the kallikrein-kinin system, and statistical analysis of the results. We analyzed a total of 1494 offspring of individuals carrying an HAE-linked mutation. RESULTS: In HAE, less male and more female offspring of mutation carriers than expected for autosomal dominant inheritance inherited the familial mutation. In addition, there were less male offspring than expected in HAEnCI. This was independent of paternal or maternal inheritance. CONCLUSION: We conclude that there is a sex- and mutation-dependent selection during early embryogenesis, possible around the time of implantation, favoring male wild-type and female mutant embryos. It also appears that 20% to 25% of male embryos carrying the HAE mutation are lost specific in HAEnCI. These findings point out that there is a potentially important role of the kallikrein-kinin system during early embryonic development.

Novel hereditary angioedema linked with a heparan sulfate 3-O-sulfotransferase 6 gene mutation.

BACKGROUND: Hereditary angioedema (HAE) is a potentially fatal disorder resulting in recurrent attacks of severe swelling. It may be associated with a genetic deficiency of functional C1 inhibitor or with normal C1 inhibitor (HAEnCI). In families with HAEnCI, HAE-linked mutations in the F12, PLG, KNG1, ANGPT1, or MYOF genes have been identified. In many families with HAEnCI the genetic cause of the disease is currently unknown. OBJECTIVE: The aim of this study was to identify a novel disease-linked mutation for HAEnCI. METHODS: The study methods comprised whole exome sequencing, Sanger sequencing analysis, pedigree analysis, bioinformatic analysis of the mutation, and biochemical analysis of parameters of the kallikrein-kinin (contact) system. RESULTS: By performing whole exome sequencing on a multigenerational family with HAEnCI we were able to identify the heparan sulfate (HS)-glucosamine 3-O-sulfotransferase 6 (HS3ST6) mutation c.430A>T (p.Thr144Ser) in all 3 affected family members who were sequenced. This gene encodes HS-glucosamine 3-O-sulfotransferase 6 (3-OST-6), which is involved in the last step of HS biosynthesis. The p.Thr144Ser mutation is likely to affect the interaction between 2 ß-sheets stabilizing the active center of the 3-OST-6 protein. CONCLUSIONS: We conclude that mutant 3-OST-6 fails to transfer sulfo groups to the 3-OH position of HS, resulting in incomplete HS biosynthesis. This likely affects cell surface interactions of key players in angioedema formation and is a novel mechanism for disease development.

Shortened Activated Partial Thromboplastin Time May Help in Diagnosing Hereditary and Acquired Angioedema.

OBJECTIVE: To evaluate whether activated partial thromboplastin time (APTT) could be used in the laboratory diagnosis of hereditary or acquired angioedema (HAE or AAE) with and without C1 inhibitor (C1-INH) deficiency. METHODS: In a prospective investigation, APTT and other coagulation parameters were determined in 149 adult patients with various types of angioedema and in 26 healthy participants (HP). RESULTS: Mean APTT was significantly shortened in HAE-C1-INH type I (p < 0.0001) and type II (p = 0.0017) and in AAE-C1-INH (p < 0.0001) compared to the HP. APTT was shortened under the reference range (26-36 s) in 33/45 (73.3%) patients with HAE-C1-INH, 10/15 (66.7%) patients with AAE-C1-INH, 4/27 (14.8%) patients with HAE with normal C1-INH, 1/32 (3.1%) patients with histaminergic angioedema, 4/30 (13.3%) patients with nonhistaminergic angioedema and in 2/26 (7.7%) HP. Thus, a shortened APTT was obtained in 8-9 times more patients with angioedema due to C1-INH deficiency when compared to patients with various forms of angioedema with normal C1-INH and also to HP. CONCLUSIONS: A shortened APTT may help to diagnose HAE-C1-INH and AAE-C1-INH when determination of C1-INH is not yet available.

Antihistamine-resistant angioedema in women with negative family history: estrogens and F12 gene mutations.

BACKGROUND: In women with sporadic recurrent angioedema with an unknown cause who are unresponsive to antihistamines and have normal C1 inhibitor activity and a negative family history of angioedema, it is unclear whether they have idiopathic angioedema or hereditary angioedema with normal C1 inhibitor, and what impact exogenous estrogens have on their angioedema. METHODS: A cohort of 147 women was analyzed for F12 exon 9 mutations and for the influence of oral contraceptives, hormonal replacement therapy, and pregnancy on their angioedema. RESULTS: A total of 142 women had idiopathic angioedema unresponsive to antihistamines. Five women had an F12 mutation and thereby hereditary angioedema with F12 mutations. Among the women with idiopathic angioedema, 63 had never taken estrogens. There was no estrogen impact in 42 women, a moderate impact in 15 women, and a severe impact in 22 women. The type and dose of estrogens did not differ in women with and without an estrogen impact. In 5 women, idiopathic angioedema disappeared after desogestrel use. Among the 5 women with hereditary angioedema with F12 mutations, angioedema symptoms occurred during 4 pregnancies, whereas no symptoms occurred during any of the 58 pregnancies in women with idiopathic angioedema. CONCLUSIONS: Women with recurrent angioedema unresponsive to antihistamines may have idiopathic angioedema or, more rarely, hereditary angioedema with F12 mutations. Both conditions may be provoked or aggravated by exogenous estrogens. In idiopathic angioedema, treatment with progestins may be helpful.

Fatal laryngeal attacks and mortality in hereditary angioedema due to C1-INH deficiency.

BACKGROUND: Hereditary angioedema due to C1 inhibitor deficiency (HAE-C1-INH) is characterized by relapsing skin swellings, abdominal pain attacks, and, less frequently, potentially life-threatening laryngeal attacks. OBJECTIVE: This study determined the mortality of patients with and without the diagnosis of HAE-C1-INH and analyzed fatal laryngeal attacks. METHODS: A cohort of 728 patients from 182 families with HAE-C1-INH was evaluated for death cases by analyzing pedigrees. Detailed information on fatal laryngeal attacks in 36 patients was obtained by questioning relatives and treating physicians. RESULTS: Of the 214 patients who had died, 70 asphyxiated during a laryngeal attack. Mortality by asphyxiation was higher in patients with undiagnosed HAE-C1-INH (63 cases) than in patients with diagnosed HAE-C1-INH (7 cases). The lifespan of asphyxiated patients with undiagnosed HAE-C1-INH was on average ∼31 years shorter than patients with undiagnosed HAE-C1-INH who died of other causes. Three phases were distinguished in the fatal laryngeal attacks. Phase 1, the predyspnea phase, lasted on average for 3.7 ± 3.2 hours (range, 0-11 hours). Phase 2, the dyspnea phase, lasted on average for 41 ± 49 minutes (range, 2 minutes to 4 hours). Phase 3, the loss of consciousness phase, lasted on average for 8.9 ± 5.1 minutes (range, 2-20 minutes). CONCLUSIONS: The high mortality in patients with undiagnosed HAE-C1-INH underscores the need to identify these patients and diagnose their condition. The analysis of fatal laryngeal attacks gives further insight into their course, thus helping to avoid fatalities in the future.

A novel mutation in the coagulation factor 12 gene in subjects with hereditary angioedema and normal C1-inhibitor.

In hereditary angioedema with normal C1-inhibitor two different missense mutations of codon p.Thr328* in the coagulation factor 12 gene have been reported in some families. In this study a novel factor 12 gene mutation, the deletion of 72 base pairs (bp) (c.971_1018+24del72*), was identified in a family of Turkish origin, in two sisters with recurrent skin swellings and abdominal pain attacks and in their symptom-free father. This deletion caused a loss of 48 bp of exon 9 (coding amino acids 324* to 340*) in addition to 24 bp of intron 9, including the authentic donor splice site of exon 9. The large deletion of 72 bp was located in the same F12 gene region as the missense mutations p.Thr328Lys* and p.Thr328Arg* reported previously. Our findings confirm the association between F12 gene mutations modifying the proline-rich region of the FXII protein and hereditary angioedema with normal C1-inhibitor.

Hereditary angioedema caused by missense mutations in the factor XII gene: clinical features, trigger factors, and therapy.

BACKGROUND: Hereditary angioedema caused by mutations in the factor XII gene is a recently described disease entity that occurs mainly in women. It differs from hereditary angioedema caused by C1 inhibitor deficiency. OBJECTIVE: To assess the clinical symptoms, factors triggering acute attacks, and treatments of this disease. METHODS: Thirty-five female patients with hereditary angioedema and the factor XII mutations p.Thr309Lys and p.Thr309Arg who came from 13 unrelated families were studied. The observation period was 8.4 years on average (range, 2-26 years). RESULTS: Patients had on average 12.7 +/- 7.9 angioedema attacks per year. Recurrent facial swellings occurred in all patients; skin swellings other than facial, abdominal pain attacks, tongue swellings, and laryngeal edema occurred less frequently. Some factors that triggered angioedema attacks were trauma, physical pressure, and emotional stress. Clinical symptoms started mainly after intake of oral contraceptives (17 women) or pregnancy (3 women). Exacerbation of the symptoms occurred after oral contraceptive use (8 women), pregnancy (7 women), hormone replacement therapy (3 women), intake of angiotensin-converting enzyme inhibitors (2 women), and an angiotensin 1 receptor blocker (1 woman). Effective treatments included C1 inhibitor concentrate for angioedema attacks (6 women) and, for prophylaxis, progesterone (8 women), danazol (2 women), and tranexamic acid (1 woman). No difference between mutation p.Thr309Arg and p.Thr309Lys was found. CONCLUSIONS: Facial swelling is a cardinal symptom of this condition. Estrogens may have a great influence, but this influence is highly variable. Various treatment options are available.

Kallikrein-kinin system and fibrinolysis in hereditary angioedema due to factor XII gene mutation Thr309Lys.

In a subgroup of hereditary angioedema (HAE) patients with normal C1-esterase inhibitor levels, HAE is caused by a Thr309Lys mutation in the coagulation factor XII (F12) gene. The aim of this study was to examine elements of the kallikrein-kinin system ('contact system') and the downstream-linked coagulation, complement and fibrinolytic systems in the plasma of six patients with HAE caused by the Thr309Lys mutation and healthy probands. Blood samples were taken from participants during the symptom-free interval between attacks. Samples were analyzed for activity and concentrations of components of the kallikrein-kinin system and linked enzyme systems. The mean FXII clotting activity was 90% in patients with the FXII mutation, and the concentration of FXIIa was 4.1 ng/ml; this did not differ from healthy probands. Mean prekallikrein amidolytic activity and high-molecular-weight kininogen clotting activity were 130 and 144%, respectively, both higher than in healthy probands. The mean kallikrein-like activity of the HAE patients was 11.4 U/l and did not differ from healthy probands. There was no difference in FXII surface activation by silicon dioxide or in kallikrein-like activity with and without activation by dextran sulfate. Contrary to the results of a recently published study, no indication that the Thr309Lys mutation causes a 'gain-of-function' of FXIIa was observed in this investigation.

Stability of Beriplast P fibrin sealant: storage and reconstitution.

This study was performed to investigate the stability of Beriplast P fibrin sealant (FS) across a range of storage conditions, both pre- and post-reconstitution. Storage stability of the FS was evaluated during long-term refrigeration (24 months) with or without interim storage at elevated temperatures (40 degrees C for 1 week and 25 degrees C for 1 and 3 months). Stability of individual FS components was assessed by measuring: fibrinogen content, Factor XIII activity (FXIII), thrombin activity and aprotinin potency. The package integrity of each component was also checked (sterility testing, moisture content and pH). Storage stability was also evaluated by testing the reconstituted product for adhesion (tearing force testing after mixing the solutions) and sterility. Reconstitution stability was evaluated following 3-months' storage, for up to 50 h post-reconstitution using the same tests as for the storage stability investigations. Pre-defined specifications were met for fibrinogen content, Factor XIII activity, and thrombin activity, demonstrating storage stability. Package integrity and the functionality and sterility of the reconstituted product were confirmed throughout. Reconstitution stability was demonstrated for up to 50 h following reconstitution, in terms of both tearing force and sterility tests. In conclusion, the storage stability of Beriplast P was demonstrated over a range of 24-month storage schedules including interim exposure to elevated temperature, and the reconstituted product was stable for up to 50 h.

A comparison of fibrin sealants in relation to their in vitro and in vivo properties.

INTRODUCTION: Fibrin sealants (FS) have been used for many years to facilitate hemostasis and to provide suture support and sealing/adhesion of tissues after surgery. While their composition is similar, different formulations, application devices, and varying concentrations of key components mean that the properties of clots formed by individual FS can be diverse. MATERIALS AND METHODS: We performed several studies, including animal models, to compare the properties of 12 different commercially available FS/application device combinations using partial liver and kidney resection models to assess hemostatic efficacy and a novel pig skin model to measure adhesive clot strength. The quality of mixing was determined using colored spray images. RESULTS: Although the FS tested shared the principle of combining fibrinogen and thrombin, major differences were found between the individual preparations with regard to hemostatic efficacy. Two pre-requisites for successful early hemostasis were identified--adequate clottable protein content and the ability of the application device to effectively mix the fibrinogen and thrombin components of the FS. Factor XIII activity was a key determinant in prevention of re-bleeding and premature clot lysis. Furthermore, FS lacking measurable factor XIII activity formed the weakest, softest clots. CONCLUSIONS: Clearly, all FS are not the same, and their different characteristics may potentially translate into different clinical outcomes. In our studies, while all FS tested performed well on individual parameters, Beriplast P (Aventis Behring) was the foremost FS in consistently providing early hemostasis, minimizing the risk of re-bleeding, and providing strong adhesive clots capable of resisting mechanical forces.