Hereditary Angioedema Type 1 with Recurrent Dizziness.

A 41-year-old woman presented with recurrent dizziness. After an attack of dizziness, she felt edematous sensations in her hands. However, according to photographs taken during the attack, the edema on the back of the patient's hands and fingers appeared mild. Laboratory examinations revealed a low C4 and C1 inhibitor (INH) activity. A direct sequencing analysis of C1INH revealed a pathogenic gene mutation. Based on these results, she was diagnosed with hereditary angioedema (HAE) type 1. These findings indicate that HAE can cause recurrent dizziness, and it should therefore be included in the differential diagnosis in patients with recurrent neurologic symptoms, even in the absence of severe edema.

Flow-mediated vasodilation assay indicates no endothelial dysfunction in hereditary angioedema patients with C1-inhibitor deficiency.

BACKGROUND: Hereditary angioedema with C1 inhibitor deficiency (C1-INH-HAE) is a rare, potentially life-threatening disorder characterized by recurrent edematous attacks. The edema formation is the consequence of interaction of bradykinin and various vasoactive peptides with endothelium. Besides these agents, danazol, a modified testosterone derivative used in these patients to prevent edematous attacks, can also affect the function of the endothelium, because it shifts the blood lipid profile to a pro-atherogenic phenotype. OBJECTIVE: To assess the endothelial function in C1-INH-HAE patients and in healthy matched controls. METHODS: To evaluate the endothelial function, we used the flow-mediated dilation method measured in the region of the brachial artery in 33 C1-INH-HAE patients and in 30 healthy matched controls. Laboratory measurements of standard biochemical parameters were performed on computerized laboratory analyzers. RESULTS: No difference was found in endothelial function (reactive hyperemia, RH) between patients (median, 9.0; 25%-75% percentile, 6.3-12.9) and controls (median, 7.37; 25%-75% percentile, 4.52-9.93). Although we found elevated cardiovascular risk (high body mass index and low-density lipoprotein/high-density lipoprotein ratio) in danazol-treated C1-INH-HAE patients, RH values did not differ between danazol-treated and nontreated patients. Furthermore, risk factors correlated with the endothelial function only in healthy controls and patients not treated with danazol. CONCLUSION: In summary, our results did not indicate any signs of endothelial dysfunction in C1-INH-HAE patients. Moreover, the normal endothelial function in danazol-treated patients with pro-atherogenic lipid profile suggests that elevated bradykinin level or other factor(s) involved in the pathogenesis of edematous attacks may have a protective role against endothelial dysfunction and atherosclerosis.

Dominant-negative SERPING1 variants cause intracellular retention of C1 inhibitor in hereditary angioedema.

Hereditary angioedema (HAE) is an autosomal dominant disease characterized by recurrent edema attacks associated with morbidity and mortality. HAE results from variations in the SERPING1 gene that encodes the C1 inhibitor (C1INH), a serine protease inhibitor (serpin). Reduced plasma levels of C1INH lead to enhanced activation of the contact system, triggering high levels of bradykinin and increased vascular permeability, but the cellular mechanisms leading to low C1INH levels (20%-30% of normal) in heterozygous HAE type I patients remain obscure. Here, we showed that C1INH encoded by a subset of HAE-causing SERPING1 alleles affected secretion of normal C1INH protein in a dominant-negative fashion by triggering formation of protein-protein interactions between normal and mutant C1INH, leading to the creation of larger intracellular C1INH aggregates that were trapped in the endoplasmic reticulum (ER). Notably, intracellular aggregation of C1INH and ER abnormality were observed in fibroblasts from a heterozygous carrier of a dominant-negative SERPING1 gene variant, but the condition was ameliorated by viral delivery of the SERPING1 gene. Collectively, our data link abnormal accumulation of serpins, a hallmark of serpinopathies, with dominant-negative disease mechanisms affecting C1INH plasma levels in HAE type I patients, and may pave the way for new treatments of HAE.

Bacteriuria increases the risk of edematous attacks in hereditary angioedema with C1-inhibitor deficiency.

Urinary tract infections are considered among the most common infectious disorders in humans. Various infections may have a role in inducing HAE attacks. Our study intended to evaluate bacteriuria in the urinalysis of patients with C1-INH-HAE. Urine specimens contributed by 139 patients with C1-INH-HAE at the annual control visits were studied retrospectively for microorganisms. We analyzed the presence of bacteriuria in relation to the clinical symptoms. Taking into account three randomly selected urine specimens, we found that the cumulative number of edematous attacks was higher in patients with bacteriuria than in those without (P = 0.019, P = 0.022, P = 0.014). Considering the same patients, attack number was significantly higher (14.51 vs 8.63) in patients with bacteriuria than in those without (P < 0.0001). In patients with bacteriuria, we found a higher incidence of edema formation during the year before evaluation, which may suggest the triggering role of bacteriuria in the occurrence of edematous episodes.

Hereditary angioedema nationwide study in Slovenia reveals four novel mutations in SERPING1 gene.

Hereditary angioedema (HAE) is a rare autosomal dominant disease characterized by swelling of the face, lips, tongue, larynx, genitalia, or extremities, with abdominal pain caused by intra-abdominal edema. HAE is caused by mutations affecting the C1 inhibitor gene, SERPING1, resulting in low levels of C1 inhibitor (Type I HAE) or normal levels of ineffective C1 inhibitor (Type II HAE). A nationwide survey identified nine unrelated families with HAE in Slovenia, among whom 17 individuals from eight families were recruited for genetic analyses. A diagnosis of HAE was established in the presence of clinical and laboratory criteria (low C1 inhibitor antigenic levels and/or function), followed up by a positive family history. Genetic studies were carried out using PCR and sequencing to detect SERPING1 mutations in promoter, noncoding exon 1, the 7 coding exons, and exon-intron boundaries. Multiplex ligation-dependent probe amplification was performed in order to search for large deletions/duplications in SERPING1 gene. A mutation responsible for HAE was identified in patients from seven families with the disease. In HAE type I families, one previously reported substitution (Gln67Stop, c.265C>T) and four novel mutations were identified. The new mutations included two missense substitutions, Ser128Phe (c.449C>T), and Glu429Lys (c.1351G>A), together with two frameshift mutations, indel (c.49delGinsTT) and deletion (c.593_594delCT). Both families with HAE type II harbored the two well-known substitutions affecting the arginyl residue at the reactive center in exon 8, Arg444Cys (c.1396C>T) and Arg444His (c.1397G>A), respectively. In one patient only the homozygous variant g.566T>C (c.-21T>C) was identified. Our study identified four novel mutations in the Slovenian HAE population, highlighting the heterogeneity of mutations in the SERPING1 gene causing C1 inhibitor deficiency and HAE. In a single patient with HAE a homozygous variant g.566T>C (c.-21T>C) might be responsible for the disease.

New therapeutics in C1INH deficiency: a review of recent studies and advances.

Hereditary angioedema (HAE) is a genetic condition causing a significant burden of illness for affected individuals. Episodes of angioedema involving the skin, gastrointestinal tract, as well as the larynx and oropharynx are often unpredictable and cause significant morbidity and mortality. Isolation of the underlying protein deficiency, specifically the serine protease C1 inhibitor, and further description of its role in multiple physiologic cascades has led to the development of several specific therapies for HAE. This report provides a brief overview of HAE but focuses primarily on reviewing recently published clinical studies of therapeutics developed for medical management of the condition.