Molecular Genetic Screening in Patients With ACE Inhibitor/Angiotensin Receptor Blocker-Induced Angioedema to Explore the Role of Hereditary Angioedema Genes

Meta-analysis of ACE inhibitor-induced angioedema identifies novel risk locus

BACKGROUND

Angioedema is a rare but potentially life-threatening adverse drug reaction in patients receiving angiotensin-converting enzyme inhibitors (ACEis). Research suggests that susceptibility to ACEi-induced angioedema (ACEi-AE) involves both genetic and nongenetic risk factors. Genome- and exome-wide studies of ACEi-AE have identified the first genetic risk loci. However, understanding of the underlying pathophysiology remains limited.

OBJECTIVE

We sought to identify further genetic factors of ACEi-AE to eventually gain a deeper understanding of its pathophysiology.

METHODS

By combining data from 8 cohorts, a genome-wide association study meta-analysis was performed in more than 1000 European patients with ACEi-AE. Secondary bioinformatic analyses were conducted to fine-map associated loci, identify relevant genes and pathways, and assess the genetic overlap between ACEi-AE and other traits. Finally, an exploratory cross-ancestry analysis was performed to assess shared genetic factors in European and African-American patients with ACEi-AE.

RESULTS

Three genome-wide significant risk loci were identified. One of these, located on chromosome 20q11.22, has not been implicated previously in ACEi-AE. Integrative secondary analyses highlighted previously reported genes (BDKRB2 [bradykinin receptor B2] and F5 [coagulation factor 5]) as well as biologically plausible novel candidate genes (PROCR [protein C receptor] and EDEM2 [endoplasmic reticulum degradation enhancing alpha-mannosidase like protein 2]). Lead variants at the risk loci were found with similar effect sizes and directions in an African-American cohort.

CONCLUSIONS

The present results contributed to a deeper understanding of the pathophysiology of ACEi-AE by (1) providing further evidence for the involvement of bradykinin signaling and coagulation pathways and (2) suggesting, for the first time, the involvement of the fibrinolysis pathway in this adverse drug reaction. An exploratory cross-ancestry comparison implicated the relevance of the associated risk loci across diverse ancestries.

Over diagnosis of bradykinin angioedema in patients treated with angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers

Background

Bradykinin angioedemas are a potentially serious side effect of angiotensin-converting enzyme inhibitors (ACEI) and more controversially of angiotensin II receptor blockers (ARB). Their challenging diagnosis is based on the absence of any recurrence after more than 6 months of drug discontinuation; otherwise mast-cell driven angioedemas as a differential diagnosis must be considered.

Objective

The aim of this study was to determine the prevalence of recurrent angioedema in patients referred for ACEI/ARB-induced bradykinin angioedema, after more than 6 months of drug discontinuation.

Methods

We included ACEI/ARB-treated patients referred for angioedema(s) without hives and unresponsive to antihistamines, after they discontinued ACEI/ARB for at least 6 months. Any C1-inhibitor deficiency was excluded. The primary endpoint was the prevalence of patients with recurrent angioedema after more than 6 months of drug discontinuation and/or developing hives during follow-up. The secondary endpoint was the identification of epidemiological factors associated with any final diagnosis.

Results

Thirty-eight of 93 patients (41%) with a suspicion of ACEI/ARB-induced bradykinin angioedema still had recurrent angioedema (n = 27) or developed hives (n = 2) or both (n = 9) after 6 months of drug discontinuation. Good response to icatibant and facial but not oral localization were predictive for the final diagnosis of ACEI/ARB-induced bradykinin angioedema and mast-cell driven angioedema, respectively.

Conclusion

In patients referred for acquired angioedema without wheals occurring during ACEI/ARB therapy, 59% finally had a diagnosis of ACEI/ARB-induced bradykinin angioedema whereas 41% were rather diagnosed with mast-cell driven angioedema. The overdiagnosis of ACEI/ARB-induced bradykinin angioedema may deteriorate the management of severe cardiovascular conditions.

A Case of Refractory Angioedema

Angioedema is an acute disorder that affects mucous membranes and the deepest layers of the skin along with underlying tissue, marked by rapid swelling, large welts, and pain. There are 3 major subtypes of angioedema: mast-cell mediated, bradykinin-mediated, and multifactorial or unclear mechanism subtype. The most common subtype of bradykinin-mediated angioedema is ACE-inhibitor induced, which disproportionately affects African-Americans. It is most often self-limiting and usually responds to the withdrawal of the offending agent. The prolonged duration of angioedema is uncommon in the absence of a persistent stimulus, though it is more likely when there is an abnormality of the metabolic pathways, such as in hereditary angioedema or other gene polymorphisms affecting the complement system. We present a case of severe angioedema that persisted for over a month and required a tracheostomy to manage the airway.