Hereditary angioedema: a Taiwanese family with a novel gene mutation

Hereditary angioedema (HAE) is an autosomal dominant disorder caused by a deficiency of C1 esterase inhibitor (C1-INH). Affected individuals have attacks of swelling involving almost any part of the body. We studied a family with 15 living members, including a 16-year-old girl who had 3 attacks of angioedema in 2 years. Her paternal uncle had died of asphyxiation during an attack 15 years previously. We analyzed the blood of each family member for C3, C4, and C1-INH levels and sequenced the SERPING1 (formerly C1NH) gene that codes for C1-INH. Six individuals had decreased serum levels of C4 and C1-INH, and they were all found to have a single nucleotide A deletion at codon 210 of the gene, 1210fsX210, a novel mutation that accounts for the HAE in this family.     

Plasma biomarkers of acute attacks in patients with angioedema due to C1-inhibitor deficiency

Background: Cl‐inhibitor (C1‐INH) deficiency leads to recurrent attacks of mucocutaneous edema and may be inherited (hereditary angioedema [HAE]) or acquired (acquired angioedema [AAE]), which have the same clinical picture characterized by angioedema involving the skin, gastrointestinal tract, and larynx. Although cutaneous swelling is evident, abdominal angioedema is still a diagnostic challenge and attacks can mimic surgical emergencies. There is currently no laboratory marker for identifying angioedema attacks. Objective: As coagulation and fibrinolysis are activated during angioedema attacks, we assessed if plasma measurements of prothrombin fragment F1 + 2 (marker of thrombin generation) and D‐dimer (marker of fibrin degradation) can be useful for the diagnosis of angioedema because of C1‐INH deficiency, especially in case of hidden locations as abdominal attacks. Methods: In addition to complement, we measured plasma levels of F1 + 2 and D‐dimer in 28 patients with C1‐INH deficiency during acute attacks and remission, 35 patients without C1‐INH deficiency during abdominal colics, and 20 healthy subjects. Results: Plasma F1 + 2 levels were higher in patients with C1‐INH deficiency during remission than in healthy controls (P = 0.001), and further increased during cutaneous and abdominal attacks (P = 0.0001); patients without C1‐INH deficiency had normal F1 + 2 levels during abdominal colics. Plasma D‐dimer levels were higher in patients with C1‐INH deficiency during remission than in controls (P = 0.012) and increased during angioedema attacks, reaching higher levels than in patients without C1‐INH deficiency during colics (P = 0.002). Conclusions: During acute angioedema attacks, patients with C1‐INH deficiency have high prothrombin fragment F1 + 2 and D‐dimer levels, the measurement of which may have an important diagnostic value.     

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.     

Normal C1 inhibitor mRNA expression level in type I hereditary angioedema patients: newly found C1 inhibitor gene mutations

BACKGROUND: C1 esterase inhibitor (C1INH) plays a key role in the classical pathway of the complement cascade. Mutations in this gene cause a decreased level of antigenic (type I hereditary angioedema, HAE) or functional (type II HAE) C1INH. OBJECTIVE: To find novel mutations in C1INH and evaluate the expression of C1INH gene in HAE patients. METHODS: Direct sequencing mutation analysis was performed for genomic DNA from three unrelated families (14 HAE patients and 18 family members). Genomic DNA from one family was also analyzed for larger genomic rearrangements, using Southern blotting analysis. We used real-time quantitative polymerase chain reaction (PCR) to evaluate C1INH mRNA expression level. RESULTS: Four mutations in exons (2,311 T-->C, 14,034 G-->A, 16,830 G-->A, and 16,979-16,980 G insertion) and four in introns (738 G-->A, 8,531 A-->G, 14,254 A-->G, and 14,337-14,378 TT deletion) were found. Interestingly, all of the nine patients in one family share the same mutation of Gly345Arg (14,034 G-->A) in the seventh exon. In another family, a single base mutation near the splice site (14,254 A-->G) was found in all of the three patients. In the last family, although a significant mutation was not found by direct sequencing, patients showed an abnormal 16 kb fragment in addition to the normal allele (21 kb Bcl I fragment). The C1INH mRNA expression of HAE patients in two families was not significantly different compared with that of normal controls. CONCLUSION: The two novel exonal mutations (G-->A and A-->G) and one large gene deletion were associated with the clinical phenotypes of HAE. Considering the normal C1INH mRNA levels but below normal protein levels in two families, their phenotypes would be associated with the post-translational defect.     

Hereditary angioedema: a family study

Hereditary angioedema (HAE) is a rare, life-threatening, autosomal dominant disease characterized by recurrent episodes of angioedema, and caused by a deficiency of the plasma protein C1-esterase inhibitor (C1-INH). Clinical manifestation of HAE may first develop during childhood but typically presents around puberty with nonpruritic and non-pitting edema of the subcutaneous and mucosal tissues. Up to now, there has been no published report of HAE case in Taiwan. We reported a 33 year-old female patient who had recurrent painful swelling of face and hands since 27 years of age. She first suffered from sudden onset of painful swelling of the eyelids and lips in August 1998 when she was pregnant for the first time. Subsequently, similar episodes recurred for a few times. Her blood test disclosed that her C3 and C4 were 125 mg/dl and 6 mg/dl, respectively. Her uncle died of laryngeal edema at the age of 30 years. Her father and elder brother also had the similar history of recurrent facial and hand swelling. The C4 levels of her elder brother were 6 mg/dl and 13.3 mg/dl on two separate occasions. The C1-INH antigen serum level and functional assay of the index patient and ten other family members were studied. A total of seven members of the family were confirmed to have type 1 HAE as evidenced by the low C4 and low C1-INH antigenic level and functional activity. Two of the seven cases were asymptomatic up to the date of our report.     

Current update on cellular and molecular mechanisms of hereditary angioedema

ObjectiveTo provide an update on the molecular mechanisms of hereditary angioedema (HAE).Data SourcesMEDLINE and PubMed databases were searched to identify pertinent articles using the following key terms: hereditary angioedema, angioedema, C1 inhibitor, bradykinin, contact system, factor XII, mechanism, pathophysiology, severity, permeability, and estrogen.Study SelectionsArticles were selected based on their relevance to the subject matter.ResultsAlthough the biochemical basis of “classic” HAE is known to result from C1 esterase inhibitor (C1INH) deficiency, a new form, HAE with normal C1INH, has been identified. HAE types I and II are caused by mutations in the SERPING1 gene that result in decreased plasma levels of functional C1INH. In HAE with normal C1INH, mutations in the F12 gene have been identified in a subset of individuals, but the genetic defect remains unknown in most patients. The primary mediator of swelling in HAE is bradykinin, a product of the plasma contact system that increases vascular permeability. HAE disease severity is highly variable and may be influenced by polymorphisms in other genes and other factors, such as hormones, trauma, stress, and infection.ConclusionHereditary angioedema is a heterogeneous disorder with a complex pathophysiology. Implicated genes include SERPING1 and FXII in patients with HAE from C1INH deficiency and HAE with normal C1INH levels, respectively. Disease severity is highly variable.     

SERPING1 mutation update: Mutation spectrum and C1 Inhibitor phenotypes

C1 inhibitor (C1Inh) deficiency is responsible for hereditary angioedema (C1‐INH‐HAE) and caused by variants of the SERPING1/C1INH/C1NH gene. C1Inh is the major control of kallikrein–kinin system. C1Inh deficiency leads to its uncontrolled activation, with subsequent generation of the vasoactive peptide bradykinin. This update documents 748 different SERPING1 variants, including published variants and additional 120 unpublished ones. They were identified as heterozygous variants (n = 729), as homozygous variants in 10 probands and as compound heterozygous variants (nine combinations). Six probands with heterozygous variants exhibited gonadal mosaicism. Probands with heterozygous (n = 72) and homozygous (n = 1) variants were identified as de novo cases. Overall, 58 variants were found at positions showing high residue conservation among serpins, and have been referred to as a mousetrap function of C1Inh: reactive center loop, gate, shutter, breach, and hinge. C1Inh phenotype analysis identified dysfunctional serpin variants with failed serpin–protease association and a residual 105‐kDa species after incubation with target protease. Regarding this characteristic, in conditions with low antigenic C1Inh, 74 C1‐INH‐HAE probands presented with an additional so‐called intermediate C1‐INH‐HAE phenotype. The present update addresses a comprehensive SERPING1 variant spectrum that facilitates genotype–phenotype correlations, highlighting residues of strategic importance for serpin function and for identification of C1Inh deficiency as serpinopathy.     

A phase I study of recombinant human C1 inhibitor in asymptomatic patients with hereditary angioedema

BACKGROUND: Hereditary angioedema (HAE) is a congenital disorder with recurrent attacks of localized swelling of submucosal tissue, subcutaneous tissue, or both caused by a deficiency of the plasma protein C1 inhibitor (C1 esterase inhibitor [C1INH]). OBJECTIVE: We sought to evaluate the effects of recombinant human C1INH (rhC1INH) isolated from the milk of transgenic rabbits in 12 asymptomatic patients with HAE. METHODS: rhC1INH was intravenously administered at doses of 6.25 to 100 U/kg on 2 occasions. RESULTS: rhC1INH appeared safe and was well tolerated. The course of functional C1INH in plasma showed a full initial recovery (dose-normalized maximum concentration of about 0.02 U/mL/U/kg) and a dose-dependent clearance of rhC1INH. After infusion of rhC1INH at 100 U/kg, a clearance of approximately 13 mL/min, a half-life of approximately 3 hours, and a volume of distribution of approximately 3 L were observed. Infusion at this dose led to functional C1INH levels in plasma of at least twice the normal level for about 2 hours and greater than 0.4 U/mL for about 9 hours. rhC1INH displayed dose-dependent biologic activity by increasing the C4 level, which was about 2-fold at 12 hours after rhC1INH at 100 U/kg, and decreasing levels of cleaved C4. CONCLUSION: The observed safety profile and biologic activity of rhC1INH warrants further clinical studies to assess its efficacy in treating HAE attacks.     

Recombinant C1-Inhibitor

Background

Recombinant human C1-inhibitor (rhC1INH; Ruconest?) has been developed for treatment of acute angioedema attacks in patients with hereditary angioedema (HAE) due to heterozygous deficiency of C1INH. Previous reports suggest that administration of plasma-derived C1INH products may be associated with an increased risk for thromboembolic complications.

Objectives

Our aim is to evaluate the effects of rhC1INH on coagulation and fibrinolysis in symptomatic HAE patients.

Methods

Levels of various coagulation and fibrinolytic parameters were determined in pre- and postexposure plasma samples from HAE patients included in a randomized clinical trial. Patients were treated with either saline, or 50 or 100 U/kg rhC1INH for an acute angioedema attack.

Results

Prior to rhC1INH treatment, the majority of patients had low to normal activated partial thromboplastin times (aPTT) and increased levels of prothrombin fragment 1+2, thrombin-antithrombin complexes, D-dimers and plasmin-antiplasmin complexes, all of which indicate activation of both coagulation and fibrinolysis. Infusion of rhC1INH at doses up to 100 U/kg did not affect these parameters except for a dose-dependent prolongation of aPTT, confirming that rhC1INH is an inhibitor of the contact system, and that F1+2 levels decreased.

Conclusion

Coagulation and fibrinolytic systems are activated in HAE patients suffering from an acute angioedema attack. Treatment with rhC1INH at 50 or 100 U/kg had no effect on parameters reflecting activation of these systems except for a significant effect on aPTT, which likely reflects a pharmacodynamic effect of rhC1INH, and a reduction on plasma levels of the prothrombin activation fragment F1+2. We conclude that these results argue against a prothrombotic effect of treatment with this rhC1INH product in HAE patients.     

Comparing acquired angioedema with hereditary angioedema (types I/II): findings from the Icatibant Outcome Survey

Icatibant is used to treat acute hereditary angioedema with C1 inhibitor deficiency types I/II (C1‐INH‐HAE types I/II) and has shown promise in angioedema due to acquired C1 inhibitor deficiency (C1‐INH‐AAE). Data from the Icatibant Outcome Survey (IOS) were analysed to evaluate the effectiveness of icatibant in the treatment of patients with C1‐INH‐AAE and compare disease characteristics with those with C1‐INH‐HAE types I/II. Key medical history (including prior occurrence of attacks) was recorded upon IOS enrolment. Thereafter, data were recorded retrospectively at approximately 6‐month intervals during patient follow‐up visits. In the icatibant‐treated population, 16 patients with C1‐INH‐AAE had 287 attacks and 415 patients with C1‐INH‐HAE types I/II had 2245 attacks. Patients with C1‐INH‐AAE versus C1‐INH‐HAE types I/II were more often male (69 versus 42%; P = 0·035) and had a significantly later mean (95% confidence interval) age of symptom onset [57·9 (51·33–64·53) versus 14·0 (12·70–15·26) years]. Time from symptom onset to diagnosis was significantly shorter in patients with C1‐INH‐AAE versus C1‐INH‐HAE types I/II (mean 12·3 months versus 118·1 months; P = 0·006). Patients with C1‐INH‐AAE showed a trend for higher occurrence of attacks involving the face (35 versus 21% of attacks; P = 0·064). Overall, angioedema attacks were more severe in patients with C1‐INH‐HAE types I/II versus C1‐INH‐AAE (61 versus 40% of attacks were classified as severe to very severe; P < 0·001). Median total attack duration was 5·0 h and 9·0 h for patients with C1‐INH‐AAE versus C1‐INH‐HAE types I/II, respectively.     

A Case of Hereditary Angioedema in a 7-Year-Old Korean Girl

Hereditary angioedema (HAE) is a rare autosomal dominant disease that usually occurs in adolescence and early adulthood. It is characterized by recurrent non-pitting edema involving the skin and intestinal tract, especially the extremities and face. It is not associated with urticaria and pruritus. The cause is known to be the deficiency of C1 inhibitor. We herein report a 7-year-old girl with HAE who had recurrent episodes of swelling of the extremities and face without urticaria and pruritus. Her great grandmother had suffered from the same symptoms. The level of serum C4 was 8.01 mg/dL (normal: 10-40 mg/dL). The level of C1 inhibitor was 5.0 mg/dL (normal: 18-40 mg/dL). To our knowledge, this is the first pediatric case with typical clinical symptoms of HAE and C1 esterase inhibitor deficiency in Korea.     

C1-inhibitor deficiency and angioedema

C1-inhibitor deficiency can be inherited or acquired; both conditions lead to recurrent angioedema that can be life threatening when the larynx is involved (hereditary angioedema, HAE; acquired angioedema, AAE). The genetic defect is due to the heterozygous deficiency of C1-Inh that is transmitted as an autosomal dominant trait. Mutations causing HAE have been found distributed over all exons and splice sites of C1-Inh structural gene: only a few of them have been found more than once. Depending on DNA defect, C1-Inh is not transcribed, or not translated or not secreted. Finally, in 15% of HAE patients, an antigenically normal, but non-functional C1-Inh is present in serum (HAE type II). C1-Inh deficiency can be acquired, due to an accelerated consumption. Such an accelerated consumption can depend on circulating autoantibodies that bind C1-Inh causing its inactivation and catabolism; or to associated diseases, usually lymphoproliferative diseases, that consume C1-Inh with different mechanisms. Effective therapies can prevent or revert angioedema symptoms in C1-Inh deficiency, the main problem of this condition remaining misdiagnosis. The common knowledge that angioedema is an allergic symptom frequently prevents a correct diagnostic approach: C1-Inh deficiency goes unrecognized and the disease can still be lethal. Correct prophylactic treatment is based on attenuated androgens in HAE and on antifibrinolytic agents in AAE. Life threatening laryngeal attacks and severe abdominal attacks are effectively reverted, in both conditions, with C1-Inh plasma concentrate. A special remark to this treatment should be made for autoantibody-mediated AAE where very high doses can be needed depending on the rate of C1-Inh consumption.     

Clinical, biochemical, and genetic characterization of a novel estrogen-dependent inherited form of angioedema

BACKGROUND: Two genetic forms of hereditary angioedema (HAE) are currently recognized. Both are transmitted in an autosomal dominant manner and are characterized by recurrent episodes of localized angioedema. Involvement of the gut leads to episodes of severe abdominal pain, and laryngeal involvement can lead to airway obstruction and even death. One type results from heterozygosity for a nonexpressed C1 inhibitor allele, and the other results from heterozygosity for a nonfunctional C1 inhibitor allele. OBJECTIVE: This report identifies a third type of HAE, with a unique estrogen-dependent phenotype. METHODS: Detailed medical histories were obtained from family members, and a pedigree was constructed to ascertain the mode of inheritance. Determination of serum complement factors, C1 inhibitor protein, C1 inhibitor function, coagulation factor XII, plasma prekallikrein, high molecular weight kininogen, and selected DNA sequences were performed in affected members by using standard assays. RESULTS: Episodes of angioedema were clinically indistinguishable from those associated with previously described forms of HAE; however, these occurred only during pregnancy or the use of exogenous estrogens. Patients were otherwise asymptomatic, except for one patient who had acetyl salicylic acid/nonsteroidal anti-inflammatory drug-related angioedema later in life. History was available for members spanning 4 generations, and affected individuals were identified in 3 generations. Of 46 family members, phenotype could be determined in 13 members. Seven were affected, and 6 were not. One male of undetermined phenotype was an obligate carrier. The unique estrogen-dependent nature of the phenotype means that the status of several members in the third and fourth generation remains unknown. The disorder appears to be transmitted in an autosomal dominant fashion, although other modes of inheritance cannot be excluded entirely. C1 inhibitor protein, C1 inhibitor function, C2, C4, C1q, coagulation factor XII, prekallikrein, and high molecular kininogen were normal in 3 affected family members during asymptomatic periods. DNA sequencing revealed no abnormality in 3 patients in the coding region of the gene encoding C1 inhibitor or in the 5' flanking regions of the genes encoding C1 inhibitor and factor XII. CONCLUSIONS: This family appears to have a novel form of inherited angioedema that does not result from C1 inhibitor deficiency or dysfunction. The phenotype is uniquely estrogen dependent. Implications for diagnosis and treatment are discussed. Further studies are required to define the exact nature of the genetic abnormality involved.     

Immunogenicity Assessment of Recombinant Human C1-Inhibitor

Background and Objective: Recombinant human C1-inhibitor (rhC1INH) is used to treat acute angioedema attacks in hereditary angioedema (HAE) due to a genetic C1INH deficiency. Recombinant proteins in general may induce antibody responses and therefore evaluation of such responses in the target population is an essential step in the clinical development program of a recombinant protein. Here we report the assessment of the immunogenicity of rhC1INH in symptomatic HAE patients. Methods: Blood samples collected before and after administration of rhC1INH were tested for antibodies against plasma-derived (pd) or rhC1INH, or against host-related impurities (HRI). Above cut-off screening results were confirmed with displacement assays, and also tested for neutralizing anti-C1INH antibodies. Finally, the relation of antibodies to clinical efficacy and safety of rhC1INH was analyzed. Results: Data from 155 HAE patients who received 424 treatments with rhC1INH were analyzed. 1.5% of all pre-exposure tests and 1.3% of all post-exposure tests were above the cut-off level in the screening assay for anti-C1INH antibodies. Six patients (3.9%) had anti-rhC1INH antibodies positive in the confirmatory assay. In two patients, confirmed antibodies were pre-existing with no increase post-exposure; in three patients, the antibodies occurred on a single occasion post-exposure; and in one patient, on subsequent occasions post-exposure. Neutralizing anti-pdC1INH antibodies were not found. Anti-HRI antibodies in the screening assay occurred in <0.7% of the tests before exposure to rhC1INH, in <1.9% after first exposure and in <3.1% after repeat treatment with rhC1INH. Five patients had anti-HRI antibodies positive in the confirmatory assay. In one patient, the antibodies were pre-existing, whereas in three of the 155 rhC1INH-treated patients (1.9%), confirmed anti-HRI antibodies occurred at more time points. Antibody findings were not associated with altered efficacy of rhC1INH or adverse events. Conclusion: These results indicate a reassuring immunosafety profile of rhC1INH as a treatment for acute HAE attacks.     

A UK national audit of hereditary and acquired angioedema

Hereditary angioedema (HAE) and acquired angioedema (AAE) are rare life‐threatening conditions caused by deficiency of C1 inhibitor (C1INH). Both are characterized by recurrent unpredictable episodes of mucosal swelling involving three main areas: the skin, gastrointestinal tract and larynx. Swelling in the gastrointestinal tract results in abdominal pain and vomiting, while swelling in the larynx may be fatal. There are limited UK data on these patients to help improve practice and understand more clearly the burden of disease. An audit tool was designed, informed by the published UK consensus document and clinical practice, and sent to clinicians involved in the care of HAE patients through a number of national organizations. Data sets on 376 patients were received from 14 centres in England, Scotland and Wales. There were 55 deaths from HAE in 33 families, emphasizing the potentially lethal nature of this disease. These data also show that there is a significant diagnostic delay of on average 10 years for type I HAE, 18 years for type II HAE and 5 years for AAE. For HAE the average annual frequency of swellings per patient affecting the periphery was eight, abdomen 5 and airway 0·5, with wide individual variation. The impact on quality of life was rated as moderate or severe by 37% of adult patients. The audit has helped to define the burden of disease in the UK and has aided planning new treatments for UK patients.     

Hereditary angioedema: Report of a large kindred with a rare genetic variant of C1-esterase inhibitor

The hereditary angioedema syndrome (HAE) is attributed to deficiency of an _a2-glycoprotein which inhibits the activated first component of complement (Cl). This protein is also called C1 esterase inhibitor (CĪ INH). The disease seems to be transmitted as an autosomal dominant trait. Two variants of the disease have been described: both have a low level of CĪ INH activity, but in one of them a non-functional CĪ INH can be detected in the serum.
The family reported belongs to this last type. All affected members had the typical abnormalities of the complement system, namely a low level of active CĪ INH and a decreased amount of C4 and of total hemolytic complement. The presence of non-functional CĪ INH was revealed by an immunochemical assay.
The antigenic determinants of the inactive protein we have studied do not differ from those of the normal one. However, the electrophoretic mobilmities of the two proteins were slightly different inasmuch as the pathological protein migrated more slowly. This protein may be a new variant of INH.     

Five novel mutations in the C1 inhibitor gene (C1NH) leading to a premature stop codon in patients with type I hereditary angioedema

Hereditary angioedema (HAE) is a disorder characterised by recurrent attacks of localized subcutaneous or submucosal edema. It is inherited in an autosomal dominant fashion and caused by a deficiency of C1 inhibitor (C1 inh, or C1NH). Most patients with HAE have an absolute deficiency of C1 inh (type I HAE) while the rest (15% of kindreds) synthetize a dysfunctional C1 inh protein (type II HAE). In this report a novel use of denaturing gradient gel electrophoresis (DGGE) followed by direct sequencing of the C1 inhibitor gene is presented. Five novel mutations, one nonsense (p.S48X) and four small deletions resulting in frameshifts (g.2264-2265delAG, g.2304delC, g.8493-8494delCC and g.16676-16677delTG) have been identified in the C1 inhibitor gene in five families with type I HAE. All of these mutations lead to premature termination of translation and thus can be considered causative of the C1 inh deficiency. Moreover, two previously described mutations in the reactive center of C1 inh, p.R444C and p.R444H, have been detected in four unrelated patients with type II HAE.     

The role of cpg sequences in the induction of anti-DNA antibodies

C1 esterase inhibitor (C1INH) is an important regulatory protein of the classical pathway of complement. Mutations in the gene for this protein cause the autosomal dominant disorder hereditary angioedema (HAE). Approximately 85% of patients with HAE have a Type I defect, characterized by a diminished level of antigenic and functional C1INH. Patients with Type II defects have sufficient protein, but one allele produces dysfunctional protein. We have sequenced the DNA from HAE patients and have discovered four previously unreported mutations. The first mutation is a splice site error at nucleotide 8721, which changes the 3' acceptor splice site AG to GG at the end of intron 5 at nucleotide 8721-8722. The second mutation is a single base insertion in exon 3 between nucleotides 2467 and 2468. The third mutation is a missense error present in the eighth exon of the C1INH; at nucleotide 16867 (amino acid 470), a T to A mutation transforms a Met to a Lys. The fourth mutation closely resembles the third mutation in that it is a missense error occurring in exon 8 in the distal hinge region; a T16827C substitution changes the Phe at amino acid 457 to Leu. This report compiles a list of 97 distinct defects in the C1INH gene that cause hereditary angioedema.     

The First Probable Case of Hereditary Angioedema in Vietnam

Hereditary angioedema (HAE) is rare disorder due to C1-inhibitor deficiency (C1-INH) that are debilitating and may be life-threatening. HAE is a lack of consensus concerning diagnosis, therapy, and management, particularly in Vietnam. In this case report, we report a 40-year-old male patient with typical clinical symptoms and family history but he showed normal C4 level, and we could not measure C1q and C1-INH level. However, the diagnosis of HAE can be made based on typical clinical symptoms and the favorable prophylactic response to danazol treatment. Based on these findings, we suggest that he has type I HAE, although he showed normal C4 level.