ABSTRACT
The genetic alteration underlying the great majority of primary angioedema with normal C1 inhibitor (nl-C1-INH-HAE) cases remains unknown. To search for variants associated with nl-C1-INH-HAE, we genotyped 133 unrelated nl-C1-INH-HAE patients using a custom next-generation sequencing platform targeting 55 genes possibly involved in angioedema pathogenesis. Patients already diagnosed with F12 alterations as well as those with histaminergic acquired angioedema were excluded. A variant pathogenicity curation strategy was followed, including a comparison of the results with those of genotyping 169 patients with hereditary angioedema due to C1-inhibitor deficiency (C1-INH-HAE), and only filtered-in variants were studied further. Among the examined nl-C1-INH-HAE patients, carriers of neither the ANGPT1 p.Ala119Ser nor the KNG1 p.Met379Lys variant were found, whereas the PLG p.Lys330Glu was detected in four (3%) unrelated probands (one homozygote). In total, 182 different variants were curated, 21 of which represented novel mutations. Although the frequency of variants per gene was comparable between nl-C1-INH-HAE and C1-INH-HAE, variants of the KNG1 and XPNPEP1 genes were detected only in nl-C1-INH-HAE patients (six and three, respectively). Twenty-seven filtered variants in 23 different genes were detected in nl-C1-INH-HAE more than once, whereas 69/133 nl-C1-INH-HAE patients had compound heterozygotes of filtered variants located in the same or different genes. Pedigree analysis was performed where feasible. Our results indicate the role that alterations in some genes, like KNG1, may play in disease pathogenesis, the complex trait that is possibly underlying in some cases, and the existence of hitherto unrecognized disease endotypes.
ABSTRACT
BACKGROUND: Hereditary angioedema (HAE) caused by a deficiency in functional C1 esterase inhibitor (C1INH) is characterized by recurrent episodes of cutaneous and/or mucosal/submucosal tissue swelling affecting multiple anatomic locations. Previous studies demonstrated efficacy of recombinant human C1INH (rhC1INH) for acute HAE attacks. OBJECTIVE: This study evaluated the efficacy and safety of rhC1INH (50 IU/kg) for the treatment of multiple HAE attacks in an open-label extension study. METHODS: Time to onset of symptom relief and time to minimal symptoms were assessed using a Treatment Effect Questionnaire (TEQ), a visual analog scale, and a 6-point ordinal scale Investigator Score. RESULTS: Forty-four patients received rhC1INH, and a single dose was administered for 215 of 224 (96%) attacks. Median time to beginning of symptom relief based on TEQ for the first 5 attacks was 75.0 (95% CI, 69-89) minutes, ranging from 62.5 (95% CI, 48-90) to 134.0 (95% CI, 32-119) minutes. Median time to minimal symptoms using TEQ for the first 3 attacks was 303.0 (95% CI, 211-367) minutes. rhC1INH was well tolerated. There were no discontinuations due to adverse events. No thrombotic or anaphylactic events were reported, and repeat rhC1INH treatments were not associated with neutralizing anti-C1INH antibodies. CONCLUSIONS: A single 50-IU/kg dose rhC1INH was effective for improving symptoms of an HAE attack with sustained efficacy for treatment of subsequent attacks. rhC1INH had a positive safety profile throughout the study. This study supports repeated use of rhC1INH over time in patients with HAE attacks.
