Clinical features of genetically characterized types of hereditary angioedema with normal C1 inhibitor: a systematic review of qualitative evidence

BACKGROUND

Hereditary angioedema (HAE) with normal C1 inhibitor (C1-INH) (HAEnCI) is associated with skin swellings, abdominal attacks, and the risk of asphyxia due to upper airway obstruction. Several different gene mutations linked to the HAE phenotype have been identified. Our aim was to qualitatively assess and describe the clinical differentiators of these genetically identified HAEnCI types. To achieve this, we performed a systematic literature review of patients with angioedema symptoms and a genetically confirmed diagnosis of an HAEnCI type.

RESULTS

A systematic literature search, conducted in March 2020, returned 132 records, 43 of which describe patients with symptoms of angioedema and a genetically confirmed diagnosis of an HAEnCI type. Overall, this included 602 patient cases from 220 families. HAEnCI with a mutation in the coagulation factor XII gene (F12) (HAE-FXII) was diagnosed in 446 patients from 185 families (male:female ratio = 1:10). Estrogens (oral contraceptives, hormonal replacement therapy, and pregnancy) negatively impacted the course of disease in most female patients (252 of 277). Asphyxia occurred in 2 of 446 patients. On-demand and/or long-term prophylaxis treatment included C1-INH concentrates, icatibant, progestins, and tranexamic acid. HAEnCI with a specific mutation in the plasminogen gene (HAE-PLG) was diagnosed in 146 patients from 33 families (male:female ratio = 1:3). Estrogens had a negative influence on the course of disease in the minority of female patients (14 of 62). Tongue swelling was an important clinical feature. Asphyxia occurred in 3 of 146 patients. On-demand treatment with icatibant and C1-INH concentrate and long-term prophylaxis with progestins and tranexamic acid were effective. HAEnCI with a specific mutation in the angiopoietin-1 gene (HAE-ANGPT1) was diagnosed in 4 patients from 1 family and HAEnCI with a specific mutation in the kininogen-1 gene (HAE-KNG1) in 6 patients from 1 family.

CONCLUSIONS

A number of clinical differentiators for the different types of HAEnCI have been identified which may support clinicians to narrow down the correct diagnosis of HAEnCI prior to genetic testing and thereby guide appropriate treatment and management decisions. However, confirmation of the causative gene mutation by genetic testing will always be required.

Hereditary angioedema with a mutation in the plasminogen gene

BACKGROUND

Hereditary angioedema (HAE) with normal C1-INH (HAEnCI) may be linked to specific mutations in the coagulation factor 12 (FXII) gene (HAE-FXII) or functional mutations in other genes that are still unknown. We sought to identify and characterize a hitherto unknown type of HAE with normal C1-INH and without mutation in the F12 gene.

METHODS

The study comprised analysis of whole-exome sequencing, Sanger sequencing, and clinical data of patients.

RESULTS

We detected a mutation in the plasminogen (PLG) gene in patients with HAEnCI. The mutation c.988A>G was located in exon 9 leading to the missense mutation p.Lys330Glu (K330E) in the kringle 3 domain of the PLG protein. The mutation was identified by next-generation sequencing in 14 patients with HAEnCI belonging to 4 of 7 families. Family studies revealed that this type of HAE was transmitted as an autosomal dominant trait. The PLG gene mutation was present in all studied symptomatic patients and was also found in 9 of 38 index patients from 38 further families with HAEnCI. Most patients had swelling of face/lips (78.3%) and tongue (78.3%). A total of 331 of all 3.795 tongue swellings (8.7%) were associated with dyspnea, voice changes, and imminent asphyxiation. Two women died by asphyxiation due to a tongue swelling.

CONCLUSIONS

Hereditary angioedema with a mutation in the PLG gene is a novel type of HAE. It is associated with a high risk of tongue swellings.

Treatment for hereditary angioedema with normal C1-INH and specific mutations in the F12 gene (HAE-FXII)

Hereditary angioedema with normal C1 esterase inhibitor and mutations in the F12 gene (HAE-FXII) is associated with skin swellings, abdominal pain attacks, and the risk of asphyxiation due to upper airway obstruction. It occurs nearly exclusively in women. We report our experience treating HAE-FXII with discontinuation of potential trigger factors and drug therapies. The study included 72 patients with HAE-FXII. Potential triggers included estrogen-containing oral contraceptives (eOC), hormonal replacement therapy, or angiotensin-converting enzyme inhibitors. Drug treatment comprised plasma-derived C1 inhibitor (pdC1-INH) for acute swelling attacks and progestins, tranexamic acid, and danazol for the prevention of attacks. Discontinuation of eOC was effective in 25 (89.3%) of 28 women and led to a reduction in the number of attacks (about 90%). After ending hormonal replacement therapy, three of eight women became symptom-free. Three women with exacerbation of HAE-FXII during intake of quinapril or enalapril had no further HAE-FXII attacks after discontinuation of those drugs. Eleven women were treated with pdC1-INH for 143 facial attacks. The duration of the treated facial attacks (mean: 26.6 h; SD: 10.1 h) was significantly shorter than that of the previous 88 untreated facial attacks in the same women (mean: 64.1 h; SD: 28.0 h; P < 0.01). The mean reduction in attack frequency was 99.8% under progestins after discontinuing eOC (16 women), 93.8% under tranexamic acid (four women), and 100% under danazol (three women). For patients with HAE-FXII, various treatment options are available which completely or at least partially reduce the number or duration of attacks.

Hereditary angioedema with normal C1-INH with versus without specific F12 gene mutations

BACKGROUND

Hereditary angioedema with normal C1-INH may be linked to specific mutations in the coagulation factor 12 (FXII) gene (HAE-FXII) or mutations in genes that are still unknown (HAE-unknown). To assess the differences in transmission and inheritance, clinical features, and laboratory parameters between patients with HAE-FXII and HAE-unknown.

METHODS

Sixty-nine patients with HAE-FXII from 23 unrelated families and 196 patients with HAE-unknown from 65 unrelated families were studied.

RESULTS

Both HAE-FXII and HAE-unknown are inherited as autosomal-dominant traits with incomplete penetrance. The male to female ratio was 1 : 68 in HAE-FXII and 1 : 6.3 in HAE-unknown. The maternal to paternal transmission ratio was 35 : 14 for HAE-FXII and 109 : 12 for HAE-unknown. Mean age at onset of clinical symptoms was 20.3 years in patients with HAE-FXII and 29.6 years in patients with HAE-unknown. The incidence of asphyxiation due to angioedema was similar for HAE-FXII and HAE-unknown. Oral contraceptives and pregnancies had a significantly higher impact on HAE-FXII than on HAE-unknown. Slightly decreased C1-INH activity and C4 concentration were observed in more patients with HAE-FXII than HAE-unknown. Tests for FXI and FXII activity, plasminogen activator inhibitor 1, and activated partial thromboplastin time showed variability but no significant differences between the groups. No abnormalities were found for C1-INH protein, C1q, alpha2-macroglobulin, antithrombin III, and angiotensin-converting enzyme. In families with HAE-FXII, the number of female offspring with F12 mutations was significantly increased and that of male offspring was significantly decreased.

CONCLUSIONS

HAE-FXII and HAE-unknown differ in various respects, including gender distribution, genetics, symptoms, and estrogen impact.

Risk of laryngeal edema and facial swellings after tooth extraction in patients with hereditary angioedema with and without prophylaxis with C1 inhibitor concentrate: a retrospective study

OBJECTIVE

Tooth extractions may trigger clinical symptoms of hereditary angioedema due to C1 inhibitor deficiency (HAE-C1-INH). The aim of this study was to determine how many tooth extractions were followed by symptoms of HAE-C1-INH in patients with and without preoperative short-term prophylaxis with C1 inhibitor concentrate.

STUDY DESIGN

Tooth extractions and clinical symptoms of HAE-C1-INH were determined from clinical record files of 171 patients with HAE-C1-INH.

RESULTS

Facial swelling or potentially life-threatening laryngeal edema, or both, occurred in 124/577 tooth extractions (21.5%) without prophylaxis. Similar symptoms occurred in a fewer proportion of patients undergoing extractions (16/128; 12.5%) after short-term prophylaxis with C1 inhibitor concentrate. The graded dose-response relationship was significant at P < .05.

CONCLUSIONS

Short-term prophylaxis with C1 inhibitor concentrate significantly reduces the risk of HAE-C1-INH symptoms after tooth extraction. In some patients, however, facial swellings and laryngeal edema symptoms may occur despite prophylaxis.

Long-term prophylaxis with C1-inhibitor (C1 INH) concentrate in patients with recurrent angioedema caused by hereditary and acquired C1-inhibitor deficiency

A case of hereditary angioedema (HAE) type I (inherited C1-inhibitor [C1 INH] deficiency) and a case of late-onset acquired C1 INH with angioedema is described. In both patients, long-term prophylaxis with C1 INH had become necessary because treatment with danazol and epsilon-aminocaproic acid was not effective or not tolerated. Consequently, both patients received a pasteurized concentrate of C1 INH continuously for a period of 1 year in a dosage that kept them free of symptoms. The patient with HAE was administered 500 units of C1 INH intravenously every 4 or 5 days, whereas the patient with acquired angioedema required 1000 units of C1 INH every 5 days. As a result of this long-term prophylaxis, both patients became free or nearly free from their episodes of cutaneous and internal edema. The low plasma levels of C1 INH, C4, and C2, rose. In the patient with acquired C1 INH deficiency, the swellings increasingly reappeared after 10 months, although the patient's antibody titer did not rise during treatment. No side effects were recorded during therapy. In particular, both patients remained HIV and hepatitis B antibody negative.

Coagulation factors and proteinase inhibitors in the plasma of children with acute lymphoblastic leukoses. Behaviour before and during treatment according to Protocol I of the Cooperative Leukaemia Study COALL-80

The thrombocyte count, the factor XIII (F XIII) activity, the concentration of fibrinogen (F I), prothrombin (F II), fibronectin (CIG), albumin and the proteinase inhibitors antithrombin III (AT III), alpha 2-macroglobulin (A2M), alpha 1-antitrypsin (A1A) and Cl-esterase inactivator (Cl-INA) were determined in ten children with acute lymphoblastic leukaemia (ALL). Changes due to the disease and to therapy were observed. Before the start of treatment the patients had thrombocytopenia secondary to the disease, and the proteinase inhibitors--especially Cl-INA and A1A--were raised. During the induction phase the thrombocyte count rose but there was also a marked increase in the concentration of F II and CIG. During the consolidation phase there was a general fall in protein concentration under L-asparaginase medication. The cause was attributed to a disorder of protein synthesis. The concentration of the factors studied rose again during maintenance therapy.

Interaction between C1-INA, coagulation, fibrinolysis and kinin system in hereditary angioneurotic edema (HANE) and urticaria

The C1-inactivator plays an important role not only in the initial phases of the complement system, but also in those of the coagulation, fibrinolysis and kinin systems. The present study was concerned with the reciprocal influence of decreased C1-inactivator levels in patients with hereditary angioneurotic edema (HANE, HAE). In 13 HANE-I patients there were significantly increased levels of the coagulation factors XII, XI, V, of plasminogen and of alpha 2-antiplasmin, while the factors IX and VII were decreased. Conversely, it emerged that in patients with markedly raised prephase factor levels, angioneurotic edema occurred in the presence of normal or only slightly decreased C1-inactivator levels. However, the ratio between factor XI and C1-INA activity was significantly higher than in normal and urticaria patients. Factor XII, HMWK, XI, VIII and V levels were significantly raised in 10 patients with frank chronic urticaria, while factor VII was lowered. Numerous other factors and inhibitors of the coagulation, fibrinolysis and kinin systems were, however, normal or showed no significant differences.

Hereditary angioneurotic oedema and blood-coagulation: interaction between C1-esterase-inhibitor and the activation factors of the proteolytic enzyme systems

C-1-inactivator (C-1-INA) does not only exert its important inhibitory functions in the complement system but also in the first step in the activation of the coagulation, fibrinolytic and kallikrein system. We therefore determined in nine patients with hereditary angioneurotic oedema (HANE) with obvious quantitative or functional defects of C-1-INA, and one further patient with Quincke-type oedema of different origin, the coagulation factors of the initial phase such as Hageman factor, plasma thromboplastin antecedent (PTA) and high molecular weight kininogen (HMWK). These factors were further correlated with the concentration as well as functional activity of C-1-INA. Nine of ten patients showed a significant, sometimes even excessive, increase in the levels of factor XII (mean +/- SD = 146% +/- 63), HMWK (mean +/- SD = 126% +/- 56) and PTA (mean +/- SD = 289% +/- 294), and a decrease of C1-esterase inhibitor (C-1-inactivator), which was measured with a immunologic method (mean +/- SD = 9.6 mg/dl +/- 6.6) for its concentration as well as being measured for its activity (mean +/- SD = 30.4% +/- 24.9).

[Haemostatic changes related to extracorporeal circulation (ECC) (author's transl)]

After-bleeding not due to surgery following extracorporeal circulation (ECC) in open heart surgery has its origin in disorders of platelet number and function as well as in changes of the haemostatic balance. Not only are the plasmatic factors of the coagulation and the fibrinolytic system of importance but also their inhibitors which tend to avoid dysfunctions and overshooting reactions. To detect early the danger of an excessive bleeding tendency assays of fibrinogen (factor I), prothrombin (factor II), antithrombin III (AT III) and of alpha 2-macroglobulin (A 2 M) are recommended. A substitution therapy can be oriented by the results of these coagulation parameters.

[Recommendations for transfusion therapy. Volume substitution, raising oxygen transport capacity and replacement of clotting factors (author's transl)]

The principal aims of whole blood transfusion therapy are simultaneous volume substitution, raising the oxygen transport capacity and the replacement of clotting factors. The necessary control factors for volume substitution are described. It must be borne in mind that the blood undergoes changes during storage which among other things affects the ability of the blood to transport oxygen and the clotting potential. Not only the destruction of thrombocytes must be considered but also the loss of activity of the proaccelerin and the antihemophilic globulin A. For this reason for massive blood transfusions using older blood conserves it is recommended that the loss of activity be compensated by antihemophilic cryoprecipitate.

[Coagulation problems associated with massive blood transfusions. An experimental study (author's transl)]

During storage banked blood show changes as far as function and concentration of their corpuscular and plasmatic ingredients are concerned. Antihaemophilic globulin (factor VIII) and pro-accelerin (factor V) in particular lose their activities so quickly that only very few activities still remain after a storage period of 3-5 days. In connection with existing primary diseases but also in trauma and shock a dilution-coagulopathy caused by insufficient supply of factors VIII and V can develop during massive transfusion, and this especially with banked blood already stored over a longer period of time. Therapy of this disturbance of coagulation consists of substituting the missing coagulation factors under heparin protection.

[Experiences on preclotting of vascular dacron protheses with and without addition of factor XIII (author's transl)]

Dacron vascular prostheses were preclotted with and without addition of human fibrin stabilizing factor (factor XIII). In our scanning electron microscopic examinations we found amorphous fibrin achieving a three dimensional net structure in the prostheses after addition of factor XIII.