Acquired Angioedema

Complex MONDO:0019624 Pathograph 22 Show in embeddings browser Angioedema Complement Disorder

Acquired angioedema due to C1 inhibitor deficiency (AAE-C1-INH) is a rare, nonhereditary, bradykinin-mediated disorder with recurrent subcutaneous or submucosal swelling. It is defined here narrowly as acquired functional C1-INH deficiency, commonly associated with a clonal B-cell disorder, monoclonal gammopathy, excessive C1-INH consumption, or anti-C1-INH autoantibodies. This entry does not include isolated ACE-inhibitor-associated or mast-cell-mediated angioedema.

Ask OpenScientist

Ask a research question about Acquired Angioedema. OpenScientist will conduct autonomous deep research using the Disorder Mechanisms Knowledge Base and PubMed literature (typically 10-30 minutes).

Submitting...

Do not include personal health information in your question. Questions and results are cached in your browser's local storage.

6
Pathophys.
5
Phenotypes
22
Pathograph
8
Medical Actions
4
Differentials
2
Trials
20
References
1
Deep Research
⚙

Pathophysiology

6
Clonal B-Cell or Monoclonal Gammopathy-Associated C1-INH Consumption
AAE-C1-INH is frequently associated with lymphoproliferative disease or monoclonal gammopathy and may involve excessive C1-INH consumption. The exact intermediates and the causal role of a particular clone or monoclonal protein are not established in every patient.
Downstream
Acquired C1 Inhibitor Functional Deficiency Clonal B-cell or monoclonal-protein states are associated with excessive C1-INH consumption, but the required intermediates vary and are not fully resolved.
Show evidence (2 references)
PMID:37844846 SUPPORT Human Clinical
"Angioedema (AE) due to acquired C1-inhibitor (C1-INH) deficiency (AAE-C1-INH) is related to excessive consumption of C1-INH or to anti-C1-INH antibodies, and is frequently associated with lymphoproliferative syndromes or monoclonal gammopathies."
The multicenter cohort frames excessive consumption and clonal disease as common associated upstream contexts.
PMID:39756409 SUPPORT Human Clinical
"A haematological disorder was identified in 83.8% of AAE-C1-INH patients compared to 3.4% of autoimmune diseases."
The UK survey independently establishes the strength of the hematologic association.
Anti-C1-INH Autoantibody-Mediated Inactivation
In an autoantibody-positive subset, anti-C1-INH antibodies abrogate inhibitor activity and can facilitate C1s-mediated cleavage by preventing formation of a stable protease-serpin complex.
Downstream
Acquired C1 Inhibitor Functional Deficiency Anti-C1-INH autoantibodies directly reduce functional inhibitor activity.
Show evidence (2 references)
PMID:9508789 SUPPORT In Vitro
"Functional studies confirmed that the anti-C1-inh autoantibodies abrogated C1-inh activity, and their maximum effect was produced when the concentrations of C1-inh and autoantibody were approximately equimolar."
Purified patient autoantibodies directly inhibited C1-INH activity in functional experiments.
PMID:9508789 SUPPORT In Vitro
"In the presence of autoantibodies, C1s cleaves C1-inh, and a stable covalent bond between C1s and C1-inh does not form."
The experiment identifies facilitated cleavage and failed stable complex formation.
Acquired C1 Inhibitor Functional Deficiency
Secondary quantitative or functional loss of C1 inhibitor removes normal restraint on protease systems. Complement consumption produces useful low C4 and C1q diagnostic readouts, while swelling is modeled through the kallikrein-kinin and bradykinin pathway rather than through complement consumption itself.
Downstream
Bradykinin-Mediated Attack Signaling Secondary C1-INH deficiency permits bradykinin-mediated angioedema through the kallikrein-kinin system.
Show evidence (2 references)
PMID:31397881 SUPPORT Human Clinical
"Acquired angioedema due to C1-inhibitor (C1INH) deficiency (AAE) is caused by secondary C1INH deficiency leading to bradykinin-mediated angioedema episodes."
The cohort report states the defining acquired functional-deficiency mechanism.
PMID:33472202 SUPPORT Human Clinical
"The inclusion criteria involved recurrent episodes of angioedema with the first manifestation at or after the age of 40, negative family history of angioedema, and C1 inhibitor function 50% or less."
The national cohort required low C1-INH function as a defining laboratory feature.
Bradykinin-Mediated Attack Signaling
Kallikrein-kinin dysregulation produces bradykinin-mediated attacks. Direct bradykinin measurement is difficult, so this node represents the established signaling mechanism without asserting a routinely measured circulating bradykinin concentration.
Downstream
Bradykinin B2-Receptor Signaling Bradykinin activates B2-receptor signaling during C1-INH-deficiency angioedema.
Show evidence (1 reference)
PMID:34956216 SUPPORT Other
"Although bradykinin-mediated disease results mainly from disturbance in the kallikrein-kinin system, traditionally complement evaluation has been used for diagnosis."
The diagnostic review distinguishes the bradykinin mediator pathway from complement-based testing.
Bradykinin B2-Receptor Signaling
Bradykinin-receptor signaling is a proximal effector of vascular leakage in C1-INH-deficiency angioedema. Experimental data also suggest contributions from B1 and gC1q receptors, so the B2 receptor is not modeled as the only possible receptor-level contributor.
Downstream
Increased Vascular Permeability and Plasma Extravasation Bradykinin-receptor signaling contributes directly to plasma-induced vascular leakage.
Show evidence (1 reference)
PMID:19796797 SUPPORT Other
"Activation of bradykinin-mediated B2 receptor has been shown to play an important role in the onset of angioedema associated with C1 inhibitor deficiency."
The source supports B2-receptor signaling as an important proximal mechanism.
Increased Vascular Permeability and Plasma Extravasation
Attack-phase plasma and bradykinin-receptor signaling increase endothelial permeability, producing transient localized plasma extravasation in skin, abdominal tissues, and the upper airway.
endothelial cell CL:0000115 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves endothelial cell (CL:0000115). CL:0000115 is a cell type from the Cell Ontology.
positive regulation of vascular permeability GO:0043117 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased positive regulation of vascular permeability (GO:0043117). GO:0043117 is a biological process from the Gene Ontology. ↑ INCREASED
Downstream
Recurrent Angioedema Intermittent permeability and extravasation produce recurrent localized angioedema.
Facial Edema Localized vascular leakage can manifest as facial angioedema.
Laryngeal Edema Localized upper-airway leakage can produce life-threatening laryngeal edema.
Abdominal Angioedema Localized submucosal leakage can manifest as abdominal angioedema.
Peripheral Edema Localized vascular leakage can manifest as extremity or peripheral edema.
Show evidence (2 references)
PMID:19796797 SUPPORT In Vitro
"We observed that the attack phase plasma from C1 inhibitor-deficient patients caused a delayed fluorescein-labeled albumin leakage as opposed to the rapid effect of bradykinin, whereas remission plasma elicited a modest effect compared with control plasma."
Patient attack-phase plasma produced endothelial leakage in the experimental system.
PMID:42253962 SUPPORT Human Clinical
"Angioedema (AE) is characterized by intermittent, localized, and self-limiting swelling of the subcutaneous and/or submucosal tissues resulting from increased vascular permeability and plasma extravasation."
The contemporary AAE cohort report states the permeability-to-swelling relationship.
⬡

Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.
Pathograph: causal mechanism network for Acquired Angioedema Interactive directed graph showing how pathophysiology mechanisms, phenotypes, genetic factors and variants, experimental models, environmental triggers, and treatments relate through causal and linked edges.
●

Phenotypes

5
Head and Neck 1
Facial Edema HP:0000282 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is facial edema (HP:0000282), qualified as temporality recurrent. HP:0000282 is a phenotype from the Human Phenotype Ontology.
Temporal: RECURRENT
Show evidence (1 reference)
PMID:42253962 SUPPORT Human Clinical
"The most frequently affected sites were the face (90%; lips 80%), followed by the abdomen (80%) and the extremities (70%)."
The small cohort documents facial swelling without generalizing a frequency band across all patients.
Metabolism 1
Peripheral Edema HP:0012398 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is peripheral edema (HP:0012398), qualified as temporality recurrent. HP:0012398 is a phenotype from the Human Phenotype Ontology.
Temporal: RECURRENT
Show evidence (1 reference)
PMID:42253962 SUPPORT Human Clinical
"The most frequently affected sites were the face (90%; lips 80%), followed by the abdomen (80%) and the extremities (70%)."
The small cohort supports extremity involvement and the HPO term is specific to peripheral edema.
Other 3
Recurrent Angioedema HP:0100665 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is angioedema (HP:0100665), qualified as temporality recurrent. HP:0100665 is a phenotype from the Human Phenotype Ontology.
Temporal: RECURRENT
Show evidence (1 reference)
PMID:28284781 SUPPORT Human Clinical
"Diagnostic criteria included history of recurrent angioedema without wheals; decreased C1-INH antigen levels and/or functional activity of C1-INH and C4 antigen less than 50% of normal; late symptom onset (>40 years); no family history of angioedema and C1-INH deficiency."
The clinical criteria directly support recurrent angioedema without wheals.
Laryngeal Edema HP:0012027 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is laryngeal edema (HP:0012027), qualified as temporality recurrent; severity severe. HP:0012027 is a phenotype from the Human Phenotype Ontology.
Temporal: RECURRENT Severity: SEVERE
Show evidence (1 reference)
PMID:30866985 SUPPORT Human Clinical
"Acquired angioedema due to C1-inhibitor (C1-INH) deficiency (AAE-C1-INH) is a serious condition that may result in life-threatening asphyxiation due to laryngeal edema."
The cohort directly supports the dangerous laryngeal manifestation.
Abdominal Angioedema Intestinal edema HP:0005225 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is intestinal edema (HP:0005225), qualified as temporality recurrent. HP:0005225 is a phenotype from the Human Phenotype Ontology.
Temporal: RECURRENT
Show evidence (1 reference)
PMID:42253962 SUPPORT Human Clinical
"The most frequently affected sites were the face (90%; lips 80%), followed by the abdomen (80%) and the extremities (70%)."
The small cohort supports abdominal angioedema, represented with the closest specific HPO edema term.
💊

Medical Actions

8
Plasma-Derived C1 Inhibitor Concentrate
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: human C1-esterase inhibitor NCIT:C87730 NCI Thesaurus (NCIT) Relation: this treatment uses this therapeutic agent This treatment uses human C1-esterase inhibitor (NCIT:C87730). NCIT:C87730 is a therapeutic agent from the NCI Thesaurus.
Plasma-derived C1-INH concentrate is used as on-demand treatment for acute AAE-C1-INH attacks. Observational data show high attack-level effectiveness, although response and required dose can vary, particularly with anti-C1-INH antibodies.
Mechanism Target:
RESTORES Acquired C1 Inhibitor Functional Deficiency — Exogenous C1-INH supplies inhibitor activity at the defining deficient node.
Show evidence (1 reference)
PMID:30866985 SUPPORT Human Clinical
"A total of 3553 (97.7%) of the 3636 attacks were effectively treated with pdC1-INH as assessed by the patient."
Clinical response supports target engagement, while restoration of inhibitor activity is a replacement-therapy inference.
Show evidence (1 reference)
PMID:30866985 SUPPORT Human Clinical
"A total of 3553 (97.7%) of the 3636 attacks were effectively treated with pdC1-INH as assessed by the patient."
The large attack-level cohort supports plasma-derived C1-INH for on-demand treatment.
Recombinant C1 Inhibitor Concentrate
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: conestat alfa NCIT:C96366 NCI Thesaurus (NCIT) Relation: this treatment uses this therapeutic agent This treatment uses conestat alfa (NCIT:C96366). NCIT:C96366 is a therapeutic agent from the NCI Thesaurus.
Recombinant C1-INH is an alternative replacement option used for acute attacks. The available AAE cohort reports response to recombinant or plasma-derived concentrate without separating product-specific outcomes.
Mechanism Target:
RESTORES Acquired C1 Inhibitor Functional Deficiency — Recombinant C1-INH supplies inhibitor activity at the defining deficient node.
Show evidence (1 reference)
PMID:33472202 SUPPORT Human Clinical
"All patients responded to the acute attack treatment with icatibant and plasma-derived or recombinant C1 inhibitor concentrate."
The pooled cohort supports replacement at this node but does not isolate recombinant-product response.
Show evidence (1 reference)
PMID:33472202 SUPPORT Human Clinical
"All patients responded to the acute attack treatment with icatibant and plasma-derived or recombinant C1 inhibitor concentrate."
The cohort includes recombinant C1-INH among effective acute treatments but reports products in aggregate.
Icatibant On-Demand Therapy
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: icatibant CHEBI:68556 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses icatibant (CHEBI:68556). CHEBI:68556 is a therapeutic agent from Chemical Entities of Biological Interest.
Icatibant is a bradykinin B2-receptor antagonist used on demand for acute AAE-C1-INH attacks.
Mechanism Target:
INHIBITS Bradykinin B2-Receptor Signaling — Icatibant antagonizes the B2 receptor that mediates a major component of permeability signaling.
Show evidence (1 reference)
PMID:19796797 SUPPORT Other
"This finding has led to the development of novel therapeutic drugs such as the B2 receptor antagonist icatibant."
The mechanistic paper explicitly identifies icatibant as a B2-receptor antagonist.
Show evidence (1 reference)
PMID:33472202 SUPPORT Human Clinical
"All patients responded to the acute attack treatment with icatibant and plasma-derived or recombinant C1 inhibitor concentrate."
The national cohort supports acute-attack response to icatibant.
Tranexamic Acid Long-Term Prophylaxis
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: tranexamic acid CHEBI:48669 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses tranexamic acid (CHEBI:48669). CHEBI:48669 is a therapeutic agent from Chemical Entities of Biological Interest.
Tranexamic acid is a specialist long-term prophylactic option. Cohort responses are heterogeneous, and the available caches do not justify a specific causal target edge to C1-INH deficiency or the contact system.
Show evidence (2 references)
PMID:28284781 SUPPORT Human Clinical
"Thirty-four patients received long-term prophylaxis with tranexamic acid (effective in 29)"
The Milan cohort reports benefit in most treated patients.
PMID:42253962 SUPPORT Human Clinical
"Antifibrinolytic agents showed limited efficacy, whereas attenuated androgens were associated with a marked reduction in attack frequency."
A small 2026 cohort illustrates heterogeneous prophylactic response.
Emerging Off-Label Berotralstat Prophylaxis
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: berotralstat NCIT:C169808 NCI Thesaurus (NCIT) Relation: this treatment uses this therapeutic agent This treatment uses berotralstat (NCIT:C169808). NCIT:C169808 is a therapeutic agent from the NCI Thesaurus.
Berotralstat is a plasma-kallikrein inhibitor with only a three-patient AAE-C1-INH subgroup in the available real-world report. It is represented as emerging, off-label, and PARTIAL evidence rather than core established care.
Mechanism Target:
INHIBITS Bradykinin-Mediated Attack Signaling — Plasma-kallikrein inhibition is expected to reduce bradykinin generation.
Show evidence (1 reference)
PMID:35212456 SUPPORT Computational
"Berotralstat is a potent, highly selective, orally bioavailable small-molecule plasma kallikrein inhibitor that has been approved to prevent attacks of HAE in adults and children 12 years of age and older."
The source establishes the molecular target in HAE; transfer to AAE-C1-INH is mechanistic extrapolation.
Show evidence (1 reference)
PMID:37914894 SUPPORT Human Clinical
"After 6 months of treatment, a median decrease of attacks per month was noted for HAE type I patients (3.3 to 1.5) and AAE-C1-INH patients (2.3 to 1.0)."
The outcome is encouraging but derives from only three AAE-C1-INH patients.
Treat the Associated Lymphoproliferative or Monoclonal Disorder
Action: therapeutic procedureNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is therapeutic procedure (NCIT:C49236). NCIT:C49236 is a clinical intervention from the NCI Thesaurus. Ontology label: Therapeutic Procedure NCIT:C49236
Etiology-directed management of an associated lymphoma, other clonal hematologic disease, or monoclonal gammopathy can reduce angioedema activity and may normalize complement parameters.
Mechanism Target:
MODULATES Clonal B-Cell or Monoclonal Gammopathy-Associated C1-INH Consumption — Controlling the associated disorder can reduce the upstream disease context that sustains AAE-C1-INH.
Show evidence (1 reference)
PMID:33472202 SUPPORT Human Clinical
"In 6 of 7 patients (86%) treated for lymphoma, either a reduction in the frequency of angioedema attacks or both angioedema symptoms' disappearance and complement parameter normalization was observed."
Clinical improvement after lymphoma treatment supports an upstream etiology-directed strategy.
Show evidence (1 reference)
PMID:33472202 SUPPORT Human Clinical
"In 6 of 7 patients (86%) treated for lymphoma, either a reduction in the frequency of angioedema attacks or both angioedema symptoms' disappearance and complement parameter normalization was observed."
The cohort supports treating the associated lymphoid malignancy as a primary disease-control strategy.
Rituximab-Based B-Cell-Directed Therapy
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: rituximab NCIT:C1702 NCI Thesaurus (NCIT) Relation: this treatment uses this therapeutic agent This treatment uses rituximab (NCIT:C1702). NCIT:C1702 is a therapeutic agent from the NCI Thesaurus.
Rituximab-based therapy is an observationally supported, etiology-directed option, particularly for clonal B-cell or lymphoid-malignancy-associated AAE-C1-INH. Selection requires specialist hematology/immunology oversight; prophylactic standard of care remains unsettled.
Mechanism Target:
MODULATES Clonal B-Cell or Monoclonal Gammopathy-Associated C1-INH Consumption — B-cell-directed treatment can control the associated clonal context and reduce angioedema activity.
Show evidence (1 reference)
PMID:39756409 SUPPORT Human Clinical
"Rituximab monotherapy was effective in treating 9/9 splenic marginal zone lymphoma and 1/2 MGUS-associated AAE-C1-INH."
The observational response supports the target relationship but does not establish a universal prophylactic standard.
Show evidence (2 references)
PMID:37844846 SUPPORT Human Clinical
"Rituximab is an efficient and well-tolerated therapeutic option in AE, especially in lymphoid malignancies and in the absence of detectable anti-C1-INH antibodies."
The 55-patient multicenter study supports rituximab-based treatment, with subgroup-dependent response.
PMID:39756409 SUPPORT Human Clinical
"B cell depletion could be considered in treating monoclonal B cell disorder-associated-AAE-C1-INH in the absence of haematological indications."
The UK survey supports cautious consideration even when standard hematologic indications are absent.
C1-INH Short-Term Prophylaxis Before Procedures
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: human C1-esterase inhibitor NCIT:C87730 NCI Thesaurus (NCIT) Relation: this treatment uses this therapeutic agent This treatment uses human C1-esterase inhibitor (NCIT:C87730). NCIT:C87730 is a therapeutic agent from the NCI Thesaurus.
C1-INH concentrate has been used shortly before invasive diagnostic or therapeutic procedures in AAE-C1-INH. The available evidence is a small observational cohort.
Mechanism Target:
RESTORES Acquired C1 Inhibitor Functional Deficiency — Pre-procedure concentrate transiently supplies C1-INH activity at the deficient node.
Show evidence (1 reference)
PMID:42253962 SUPPORT Human Clinical
"Short-term prophylaxis with C1-INH concentrate at a dose of 1000 IU was administered to 6 patients (60%) one hour prior to"
The small cohort documents pre-procedure use; restoration remains a replacement-therapy inference.
Show evidence (2 references)
PMID:42253962 SUPPORT Human Clinical
"Short-term prophylaxis with C1-INH concentrate at a dose of 1000 IU was administered to 6 patients (60%) one hour prior to"
The source documents short-term prophylactic use before procedures in a small cohort.
PMID:42253962 SUPPORT Human Clinical
"invasive diagnostic and/or therapeutic procedures, and no AE attacks were observed during or after these procedures."
No peri-procedural attacks were observed in the treated cohort, but the sample was small and uncontrolled.
🔬

Biochemical Markers

4
Low C1 Inhibitor Function (DECREASED)
Context: Reduced functional C1-INH is the central laboratory abnormality. Antigen concentration may also be low, but functional and antigenic measurements are not interchangeable.
Pathograph Readouts
Readout Of Acquired C1 Inhibitor Functional Deficiency Negative Diagnostic
Reduced C1-INH function directly reports the defining functional-deficiency mechanism.
Show evidence (1 reference)
PMID:33472202 SUPPORT Human Clinical
"The inclusion criteria involved recurrent episodes of angioedema with the first manifestation at or after the age of 40, negative family history of angioedema, and C1 inhibitor function 50% or less."
The cohort uses reduced function as a direct disease-defining readout.
Show evidence (1 reference)
PMID:33472202 SUPPORT Human Clinical
"The inclusion criteria involved recurrent episodes of angioedema with the first manifestation at or after the age of 40, negative family history of angioedema, and C1 inhibitor function 50% or less."
The cohort explicitly required low C1-INH function.
Low C4 (DECREASED)
Context: Low C4 is a complement-consumption readout used with C1-INH function, antigen, and clinical context. It is not modeled as the mediator of edema.
Pathograph Readouts
Correlates With Acquired C1 Inhibitor Functional Deficiency Negative Diagnostic
Lower C4 correlates with the complement-consumption pattern accompanying acquired C1-INH deficiency.
Show evidence (1 reference)
PMID:28284781 SUPPORT Human Clinical
"Diagnostic criteria included history of recurrent angioedema without wheals; decreased C1-INH antigen levels and/or functional activity of C1-INH and C4 antigen less than 50% of normal; late symptom onset (>40 years); no family history of angioedema and C1-INH deficiency."
The cohort includes low C4 in the acquired C1-INH-deficiency diagnostic pattern.
Show evidence (1 reference)
PMID:28284781 SUPPORT Human Clinical
"Diagnostic criteria included history of recurrent angioedema without wheals; decreased C1-INH antigen levels and/or functional activity of C1-INH and C4 antigen less than 50% of normal; late symptom onset (>40 years); no family history of angioedema and C1-INH deficiency."
Low C4 is part of the cohort's combined diagnostic criteria.
Low or Undetectable C1q (DECREASED)
Context: Low C1q supports an acquired C1-INH-deficiency pattern but is not specific by itself and should not be treated as an exclusionary requirement.
Pathograph Readouts
Correlates With Acquired C1 Inhibitor Functional Deficiency Negative Diagnostic
Low C1q correlates with, but does not uniquely identify, acquired C1-INH deficiency.
Show evidence (1 reference)
PMID:31397881 SUPPORT Human Clinical
"When free antiC1INHAbs and malignant tumors are not detectable, diagnosis relies on the finding of low C1INH levels and/or function, lack of family history and SERPING1 mutations, age at onset and low or undetectable C1q levels, none of which is specific for AAE."
The source supports the C1q association and explicitly preserves its lack of specificity.
Show evidence (1 reference)
PMID:32753245 SUPPORT Other
"Low C1q is observed in 90% of patients, and an anti C1-inhibitor antibody is found in 50% of patients."
The recommendations summarize how often these supportive findings were observed.
C1-INH-Anti-C1-INH Immune Complexes (PRESENT)
Context: Circulating C1-INH/anti-C1-INH complexes can improve detection when free antibodies are not measurable. They are represented as a specialized diagnostic biomarker, not as a proven causal node.
Pathograph Readouts
Correlates With Anti-C1-INH Autoantibody-Mediated Inactivation Present Absent Diagnostic
Complex detection supports an anti-C1-INH antibody-associated disease context but does not prove that the measured complexes cause deficiency.
Show evidence (1 reference)
PMID:31397881 SUPPORT Human Clinical
"C1INH-antiC1INHAb complexes were found in 18 of 20 of the AAE cases, regardless of the presence or absence of detectable free anti-C1INHAbs."
The cohort establishes a diagnostic correlation without assigning causal force to the complexes.
Show evidence (1 reference)
PMID:31397881 SUPPORT Human Clinical
"Of note, nine of 20 patients showed negative free antiC1INHabs, but positive C1INH-antiC1INHAb complexes in their first measurement."
Complex testing can detect an antibody-associated pattern when free antibodies are negative.
🔬

Diagnosis

3
Complement and C1-INH Antigenic and Functional Testing
Evaluate recurrent angioedema without wheals using C4, C1-INH antigen, and C1-INH function, then interpret C1q, age, family history, and genetic findings in combination. Functional and antigenic assays should both be considered because concentration alone can miss functional deficiency.
Results: Low C1-INH function with low antigen and/or C4 supports C1-INH-deficiency angioedema. Low C1q supports the acquired form, but no single laboratory or historical feature is specific on its own.
Show evidence (2 references)
PMID:34956216 SUPPORT Other
"Diagnosis is established by nephelometry, turbidimetry, or radial immunodiffusion for quantitative measurement of C1 inhibitor, and chromogenic assay or ELISA has been used for functional C1-INH analysis."
The diagnostic review identifies quantitative and functional assay approaches.
PMID:31397881 SUPPORT Human Clinical
"When free antiC1INHAbs and malignant tumors are not detectable, diagnosis relies on the finding of low C1INH levels and/or function, lack of family history and SERPING1 mutations, age at onset and low or undetectable C1q levels, none of which is specific for AAE."
The source supports a combined interpretation and cautions against treating any component as specific alone.
Specialized Anti-C1-INH Antibody and Immune-Complex Testing
Free anti-C1-INH antibody testing can support the acquired diagnosis. C1-INH/anti-C1-INH complex assays may add information in specialist or research settings, especially when free antibody testing is negative, but are not represented as a universal standalone diagnostic test.
Results: Detection of free anti-C1-INH antibodies or C1-INH/anti-C1-INH complexes supports an antibody-associated AAE-C1-INH context.
Show evidence (2 references)
PMID:32753245 SUPPORT Other
"Low C1q is observed in 90% of patients, and an anti C1-inhibitor antibody is found in 50% of patients."
The recommendations identify anti-C1-INH antibodies as a frequent supportive finding.
PMID:36726161 SUPPORT Human Clinical
"Measurement of CAC is recommended to be done parallelly with C1-INH-Ab, so as to detect both free and bound antibodies."
A specialist cohort recommends parallel complex and free-antibody measurement, but broader clinical utility remains unsettled.
Evaluation and Surveillance for an Associated Clonal Disorder
Evaluate for an associated hematologic or monoclonal disorder and continue longitudinal reassessment when initial studies are unrevealing, because angioedema can precede recognition of the underlying condition.
Results: Identification of lymphoma, another clonal hematologic neoplasm, or monoclonal gammopathy can explain the associated disease context and guide etiology-directed management.
Show evidence (2 references)
PMID:39756409 SUPPORT Human Clinical
"A haematological disorder was identified in 83.8% of AAE-C1-INH patients compared to 3.4% of autoimmune diseases."
The UK survey supports systematic evaluation for an associated hematologic disorder.
PMID:42253962 SUPPORT Human Clinical
"Clonal hematologic neoplasms were present in 60% of patients and monoclonal gammopathy of undetermined significance in 30%, with angioedema preceding the diagnosis of the underlying condition in 60% of cases."
The 2026 cohort shows why continued surveillance can matter after angioedema presentation.
📈

Progression

1
Recurrent episodic attacks
Age: Usually adult onset, but diagnosis before age 40 can occur
AAE-C1-INH usually begins in later adulthood and produces discrete attacks rather than continuously progressive edema. Age at onset is supportive context, not an absolute diagnostic cutoff.
Show evidence (2 references)
PMID:33472202 SUPPORT Human Clinical
"The median age of the symptom onset was 59.5 years, and the median diagnosis delay was 1 year."
The Czech cohort supports typical later-adult onset and diagnostic delay.
PMID:39756409 SUPPORT Human Clinical
"The median age at AAE-C1-INH diagnosis was 65 years with 3.4% of patients diagnosed below 40 years."
The larger UK survey shows that an age cutoff of 40 years is not absolute.
📊

Prevalence

1
Czech Republic
Point Prevalence 0.131579 per 100,000 1–9 per 1,000,000
Nationwide retrospective ascertainment estimated AAE-C1-INH prevalence at approximately 1 per 760,000 people in the Czech Republic. This is a country-specific estimate for an ultra-rare disease, not a global rate.
Show evidence (1 reference)
PMID:33472202 SUPPORT Human Clinical
"The prevalence of AAE-C1-INH in the Czech Republic is about 1:760,000."
The nationwide cohort supplies the normalized country-specific estimate.
🔀

Differential Diagnoses

4

Conditions with similar clinical presentations that must be differentiated from Acquired Angioedema:

Hereditary Angioedema with C1 Inhibitor Deficiency MONDO:0019623
Overlapping Features HAE-C1-INH can produce an indistinguishable bradykinin-mediated attack pattern and low C1-INH. Family history, earlier onset, and a pathogenic SERPING1 finding favor hereditary disease, but de novo or late-presenting HAE means no single feature is decisive.
Distinguishing Features
  • A family history, earlier onset, or a pathogenic SERPING1 finding favors HAE-C1-INH.
  • Later onset, low C1q, an associated clonal disorder, or anti-C1-INH antibodies supports AAE-C1-INH, but these features must be interpreted together.
Show evidence (3 references)
PMID:42253962 SUPPORT Human Clinical
"Acquired angioedema due to C1 inhibitor deficiency (AAE-C1INH) is a rare bradykinin-mediated condition that may mimic hereditary angioedema (HAE)."
The recent cohort explicitly identifies HAE as a clinical mimic.
PMID:42165046 SUPPORT Other
"The diagnostic strategy emphasizes early clinical recognition based on characteristic features, including recurrent angioedema without urticaria, abdominal or laryngeal involvement, early symptom onset, and family history."
The HAE guideline supports early onset and family history as characteristic hereditary clues.
PMID:31397881 SUPPORT Human Clinical
"When free antiC1INHAbs and malignant tumors are not detectable, diagnosis relies on the finding of low C1INH levels and/or function, lack of family history and SERPING1 mutations, age at onset and low or undetectable C1q levels, none of which is specific for AAE."
The source supplies the acquired clues while warning that none is individually specific.
Hereditary Angioedema with Normal C1 Inhibitor
Overlapping Features HAE with normal C1-INH can produce recurrent bradykinin-mediated attacks but lacks the defining low C1-INH antigen/function pattern of AAE-C1-INH.
Distinguishing Features
  • Normal complement and C1-INH assays argue against acquired C1-INH deficiency.
  • Family history and targeted genetic evaluation can support a normal-C1-INH hereditary form.
Show evidence (1 reference)
PMID:34956216 SUPPORT Other
"Regarding HAE with normal C1 inhibitor, complement assays' results are normal and the genetic sequencing of target genes, such as exon 9 of F12 and PLG, is the only available method."
The review distinguishes normal-C1-INH hereditary disease through normal complement assays and genetic evaluation.
ACE Inhibitor- or RAS-Blocker-Associated Angioedema
Overlapping Features Medication-associated angioedema can mimic or coexist with AAE-C1-INH. Exposure alone must not terminate the complement and C1-INH evaluation when recurrent bradykinin-mediated attacks suggest an additional cause.
Distinguishing Features
  • Review the timing of ACE inhibitor or other renin-angiotensin-system blocker exposure.
  • Low C1-INH function and the acquired complement pattern support AAE-C1-INH even when a relevant medication exposure is present.
Show evidence (1 reference)
PMID:42253962 SUPPORT Human Clinical
"Two patients developed AE episodes in association with ACE inhibitor or ARB exposure and were subsequently found to have AAE-C1INH."
The cohort demonstrates that RAS-blocker exposure and AAE-C1-INH can coexist.
Mast-Cell-Mediated Angioedema or Chronic Spontaneous Urticaria
Overlapping Features Mast-cell-mediated angioedema and chronic spontaneous urticaria can include recurrent swelling but belong to a different mechanistic endotype from acquired C1-INH-deficiency angioedema.
Distinguishing Features
  • Recurrent itchy wheals with or without angioedema favor chronic spontaneous urticaria and mast-cell activation.
  • Recurrent angioedema without wheals together with low C1-INH function and complement consumption favors AAE-C1-INH.
Show evidence (2 references)
PMID:31899843 SUPPORT Human Clinical
"Chronic spontaneous urticaria (CSU) is characterized by recurrent itchy weals and/or angioedema and is believed to be driven by mast cell activation."
The study states the wheal/itch and mast-cell pattern that distinguishes CSU from the focal disease.
PMID:38670233 SUPPORT Other
"AE is heterogeneous, can be hereditary or acquired, may occur only once or be recurrent, may exhibit wheals or not, and may be due to mast cell mediators, bradykinin, or other mechanisms."
The consensus classification supports separating mast-cell and bradykinin endotypes.
🔬

Clinical Trials

2
NCT06818474 PHASE_IV RECRUITING
Open-label Phase IV interventional study evaluating lanadelumab for long-term prophylaxis in acquired angioedema.
Target Phenotypes: angioedema HP:0100665 Human Phenotype Ontology (HP) Relation: this clinical trial targets this phenotype This clinical trial targets angioedema (HP:0100665). HP:0100665 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
clinicaltrials:NCT06818474 SUPPORT Human Clinical
"use of lanadelumab in patients with acquired angioedema"
The registry summary establishes the AAE lanadelumab study.
NCT07266805 PHASE_III RECRUITING
Randomized Phase III study evaluating deucrictibant XR for prophylaxis and deucrictibant IR for on-demand treatment of attacks in adults with AAE-C1-INH.
Target Phenotypes: angioedema HP:0100665 Human Phenotype Ontology (HP) Relation: this clinical trial targets this phenotype This clinical trial targets angioedema (HP:0100665). HP:0100665 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
clinicaltrials:NCT07266805 SUPPORT Human Clinical
"This is a Phase 3, multicenter, 3-part study, with 2 randomized, double-blind, placebo-controlled parts and an open-label extension part, to evaluate the efficacy and safety of orally administered deucrictibant XR tablet for prophylaxis, and deucrictibant IR capsule for on-demand treatment of..."
The registry summary establishes the phase, design, population, and investigational uses.
PMID:38494092 SUPPORT Human Clinical
"Three patients were enrolled; of those 3 patients, 1 completed both study parts and 2 completed only Part 2."
The prior randomized crossover evidence is limited to three patients.
{ }

Source YAML

click to show 
name: Acquired Angioedema
creation_date: "2026-05-10T16:46:20Z"
category: Complex
description: >-
  Acquired angioedema due to C1 inhibitor deficiency (AAE-C1-INH) is a rare,
  nonhereditary, bradykinin-mediated disorder with recurrent subcutaneous or
  submucosal swelling. It is defined here narrowly as acquired functional
  C1-INH deficiency, commonly associated with a clonal B-cell disorder,
  monoclonal gammopathy, excessive C1-INH consumption, or anti-C1-INH
  autoantibodies. This entry does not include isolated ACE-inhibitor-associated
  or mast-cell-mediated angioedema.
disease_term:
  preferred_term: acquired angioedema
  term:
    id: MONDO:0019624
    label: acquired angioedema
synonyms:
- AAE
- AAE-C1-INH
- acquired angioedema due to C1-inhibitor deficiency
- acquired C1 inhibitor deficiency
- acquired angioneurotic edema
- acquired bradykinin-mediated angioedema
parents:
- Angioedema
- Complement Disorder
prevalence:
- population: Czech Republic
  measure_type: POINT_PREVALENCE
  prevalence_class: BAND_1_9_PER_1000000
  rate_per_100000: 0.131579
  notes: >-
    Nationwide retrospective ascertainment estimated AAE-C1-INH prevalence at
    approximately 1 per 760,000 people in the Czech Republic. This is a
    country-specific estimate for an ultra-rare disease, not a global rate.
  evidence:
  - reference: PMID:33472202
    reference_title: "Acquired Angioedema with C1 Inhibitor Deficiency: Occurrence, Clinical Features, and Management: A Nationwide Retrospective Study in the Czech Republic Patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The prevalence of AAE-C1-INH in the Czech Republic is about 1:760,000."
    explanation: The nationwide cohort supplies the normalized country-specific estimate.
progression:
- phase: Recurrent episodic attacks
  age_range: Usually adult onset, but diagnosis before age 40 can occur
  notes: >-
    AAE-C1-INH usually begins in later adulthood and produces discrete attacks
    rather than continuously progressive edema. Age at onset is supportive
    context, not an absolute diagnostic cutoff.
  evidence:
  - reference: PMID:33472202
    reference_title: "Acquired Angioedema with C1 Inhibitor Deficiency: Occurrence, Clinical Features, and Management: A Nationwide Retrospective Study in the Czech Republic Patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The median age of the symptom onset was 59.5 years, and the median diagnosis delay was 1 year."
    explanation: The Czech cohort supports typical later-adult onset and diagnostic delay.
  - reference: PMID:39756409
    reference_title: A multi-centre UK-based survey on angioedema secondary to acquired C1 inhibitor deficiency.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The median age at AAE-C1-INH diagnosis was 65 years with 3.4% of patients diagnosed below 40 years."
    explanation: The larger UK survey shows that an age cutoff of 40 years is not absolute.
pathophysiology:
- name: Clonal B-Cell or Monoclonal Gammopathy-Associated C1-INH Consumption
  mechanism_confidence: PROVISIONAL
  description: >-
    AAE-C1-INH is frequently associated with lymphoproliferative disease or
    monoclonal gammopathy and may involve excessive C1-INH consumption. The
    exact intermediates and the causal role of a particular clone or
    monoclonal protein are not established in every patient.
  evidence:
  - reference: PMID:37844846
    reference_title: Efficacy and Safety of Rituximab-Based Treatments in Angioedema With Acquired C1-Inhibitor Deficiency.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Angioedema (AE) due to acquired C1-inhibitor (C1-INH) deficiency
      (AAE-C1-INH) is related to excessive consumption of C1-INH or to
      anti-C1-INH antibodies, and is frequently associated with
      lymphoproliferative syndromes or monoclonal gammopathies.
    explanation: The multicenter cohort frames excessive consumption and clonal disease as common associated upstream contexts.
  - reference: PMID:39756409
    reference_title: A multi-centre UK-based survey on angioedema secondary to acquired C1 inhibitor deficiency.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "A haematological disorder was identified in 83.8% of AAE-C1-INH patients compared to 3.4% of autoimmune diseases."
    explanation: The UK survey independently establishes the strength of the hematologic association.
  downstream:
  - target: Acquired C1 Inhibitor Functional Deficiency
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - accelerated C1-INH consumption or catabolism
    description: >-
      Clonal B-cell or monoclonal-protein states are associated with excessive
      C1-INH consumption, but the required intermediates vary and are not fully
      resolved.
    evidence:
    - reference: PMID:37844846
      reference_title: Efficacy and Safety of Rituximab-Based Treatments in Angioedema With Acquired C1-Inhibitor Deficiency.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Angioedema (AE) due to acquired C1-inhibitor (C1-INH) deficiency
        (AAE-C1-INH) is related to excessive consumption of C1-INH or to
        anti-C1-INH antibodies, and is frequently associated with
        lymphoproliferative syndromes or monoclonal gammopathies.
      explanation: The source supports the clinical association and consumption model, while leaving patient-specific intermediates unresolved.
- name: Anti-C1-INH Autoantibody-Mediated Inactivation
  mechanism_confidence: ESTABLISHED
  description: >-
    In an autoantibody-positive subset, anti-C1-INH antibodies abrogate
    inhibitor activity and can facilitate C1s-mediated cleavage by preventing
    formation of a stable protease-serpin complex.
  evidence:
  - reference: PMID:9508789
    reference_title: "Mechanism of action of anti-C1-inhibitor autoantibodies: prevention of the formation of stable C1s-C1-inh complexes."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Functional studies confirmed that the anti-C1-inh autoantibodies
      abrogated C1-inh activity, and their maximum effect was produced when the
      concentrations of C1-inh and autoantibody were approximately equimolar.
    explanation: Purified patient autoantibodies directly inhibited C1-INH activity in functional experiments.
  - reference: PMID:9508789
    reference_title: "Mechanism of action of anti-C1-inhibitor autoantibodies: prevention of the formation of stable C1s-C1-inh complexes."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      In the presence of autoantibodies, C1s cleaves C1-inh, and a stable
      covalent bond between C1s and C1-inh does not form.
    explanation: The experiment identifies facilitated cleavage and failed stable complex formation.
  downstream:
  - target: Acquired C1 Inhibitor Functional Deficiency
    causal_link_type: DIRECT
    description: Anti-C1-INH autoantibodies directly reduce functional inhibitor activity.
    evidence:
    - reference: PMID:9508789
      reference_title: "Mechanism of action of anti-C1-inhibitor autoantibodies: prevention of the formation of stable C1s-C1-inh complexes."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        Functional studies confirmed that the anti-C1-inh autoantibodies
        abrogated C1-inh activity, and their maximum effect was produced when
        the concentrations of C1-inh and autoantibody were approximately
        equimolar.
      explanation: The functional experiment directly supports the autoantibody-to-deficiency edge.
- name: Acquired C1 Inhibitor Functional Deficiency
  mechanism_confidence: ESTABLISHED
  description: >-
    Secondary quantitative or functional loss of C1 inhibitor removes normal
    restraint on protease systems. Complement consumption produces useful low
    C4 and C1q diagnostic readouts, while swelling is modeled through the
    kallikrein-kinin and bradykinin pathway rather than through complement
    consumption itself.
  gene_products:
  - preferred_term: C1 esterase inhibitor
    term:
      id: NCIT:C181692
      label: Plasma Protease C1 Inhibitor
  evidence:
  - reference: PMID:31397881
    reference_title: Serum complexes between C1INH and C1INH autoantibodies for the diagnosis of acquired angioedema.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Acquired angioedema due to C1-inhibitor (C1INH) deficiency (AAE) is
      caused by secondary C1INH deficiency leading to bradykinin-mediated
      angioedema episodes.
    explanation: The cohort report states the defining acquired functional-deficiency mechanism.
  - reference: PMID:33472202
    reference_title: "Acquired Angioedema with C1 Inhibitor Deficiency: Occurrence, Clinical Features, and Management: A Nationwide Retrospective Study in the Czech Republic Patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The inclusion criteria involved recurrent episodes of angioedema with the
      first manifestation at or after the age of 40, negative family history of
      angioedema, and C1 inhibitor function 50% or less.
    explanation: The national cohort required low C1-INH function as a defining laboratory feature.
  downstream:
  - target: Bradykinin-Mediated Attack Signaling
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - kallikrein-kinin system dysregulation
    description: Secondary C1-INH deficiency permits bradykinin-mediated angioedema through the kallikrein-kinin system.
    evidence:
    - reference: PMID:31397881
      reference_title: Serum complexes between C1INH and C1INH autoantibodies for the diagnosis of acquired angioedema.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Acquired angioedema due to C1-inhibitor (C1INH) deficiency (AAE) is
        caused by secondary C1INH deficiency leading to bradykinin-mediated
        angioedema episodes.
      explanation: The source directly connects secondary C1-INH deficiency to bradykinin-mediated attacks.
- name: Bradykinin-Mediated Attack Signaling
  mechanism_confidence: ESTABLISHED
  description: >-
    Kallikrein-kinin dysregulation produces bradykinin-mediated attacks.
    Direct bradykinin measurement is difficult, so this node represents the
    established signaling mechanism without asserting a routinely measured
    circulating bradykinin concentration.
  chemical_entities:
  - preferred_term: bradykinin
    term:
      id: CHEBI:3165
      label: bradykinin
  evidence:
  - reference: PMID:34956216
    reference_title: "Angioedema Without Wheals: Challenges in Laboratorial Diagnosis."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Although bradykinin-mediated disease results mainly from disturbance in
      the kallikrein-kinin system, traditionally complement evaluation has been
      used for diagnosis.
    explanation: The diagnostic review distinguishes the bradykinin mediator pathway from complement-based testing.
  downstream:
  - target: Bradykinin B2-Receptor Signaling
    causal_link_type: DIRECT
    description: Bradykinin activates B2-receptor signaling during C1-INH-deficiency angioedema.
    evidence:
    - reference: PMID:19796797
      reference_title: Novel pathogenic mechanism and therapeutic approaches to angioedema associated with C1 inhibitor deficiency.
      supports: SUPPORT
      evidence_source: OTHER
      snippet: >-
        Activation of bradykinin-mediated B2 receptor has been shown to play an
        important role in the onset of angioedema associated with C1 inhibitor
        deficiency.
      explanation: The mechanistic paper explicitly connects bradykinin-mediated B2-receptor activation with C1-INH-deficiency angioedema.
- name: Bradykinin B2-Receptor Signaling
  mechanism_confidence: ESTABLISHED
  description: >-
    Bradykinin-receptor signaling is a proximal effector of vascular leakage in
    C1-INH-deficiency angioedema. Experimental data also suggest contributions
    from B1 and gC1q receptors, so the B2 receptor is not modeled as the only
    possible receptor-level contributor.
  evidence:
  - reference: PMID:19796797
    reference_title: Novel pathogenic mechanism and therapeutic approaches to angioedema associated with C1 inhibitor deficiency.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Activation of bradykinin-mediated B2 receptor has been shown to play an
      important role in the onset of angioedema associated with C1 inhibitor
      deficiency.
    explanation: The source supports B2-receptor signaling as an important proximal mechanism.
  downstream:
  - target: Increased Vascular Permeability and Plasma Extravasation
    causal_link_type: DIRECT
    description: Bradykinin-receptor signaling contributes directly to plasma-induced vascular leakage.
    evidence:
    - reference: PMID:19796797
      reference_title: Novel pathogenic mechanism and therapeutic approaches to angioedema associated with C1 inhibitor deficiency.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        The plasma permeabilizing effect was prevented by blocking the gC1q
        receptor-high-molecular-weight kininogen interaction, was partially
        inhibited by B2 receptor or B1 receptor antagonists, and was totally
        prevented by the mixture of the 2 antagonists.
      explanation: Receptor blockade reduced or prevented plasma-induced permeability in the experimental model.
- name: Increased Vascular Permeability and Plasma Extravasation
  mechanism_confidence: ESTABLISHED
  description: >-
    Attack-phase plasma and bradykinin-receptor signaling increase endothelial
    permeability, producing transient localized plasma extravasation in skin,
    abdominal tissues, and the upper airway.
  cell_types:
  - preferred_term: endothelial cell
    term:
      id: CL:0000115
      label: endothelial cell
  biological_processes:
  - preferred_term: positive regulation of vascular permeability
    term:
      id: GO:0043117
      label: positive regulation of vascular permeability
    modifier: INCREASED
  evidence:
  - reference: PMID:19796797
    reference_title: Novel pathogenic mechanism and therapeutic approaches to angioedema associated with C1 inhibitor deficiency.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      We observed that the attack phase plasma from C1 inhibitor-deficient
      patients caused a delayed fluorescein-labeled albumin leakage as opposed
      to the rapid effect of bradykinin, whereas remission plasma elicited a
      modest effect compared with control plasma.
    explanation: Patient attack-phase plasma produced endothelial leakage in the experimental system.
  - reference: PMID:42253962
    reference_title: "Acquired angioedema due to C1 inhibitor deficiency: real-world clinical characteristics and treatment outcomes."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Angioedema (AE) is characterized by intermittent, localized, and
      self-limiting swelling of the subcutaneous and/or submucosal tissues
      resulting from increased vascular permeability and plasma extravasation.
    explanation: The contemporary AAE cohort report states the permeability-to-swelling relationship.
  downstream:
  - target: Recurrent Angioedema
    causal_link_type: DIRECT
    description: Intermittent permeability and extravasation produce recurrent localized angioedema.
    evidence:
    - reference: PMID:42253962
      reference_title: "Acquired angioedema due to C1 inhibitor deficiency: real-world clinical characteristics and treatment outcomes."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Angioedema (AE) is characterized by intermittent, localized, and
        self-limiting swelling of the subcutaneous and/or submucosal tissues
        resulting from increased vascular permeability and plasma extravasation.
      explanation: The source directly defines recurrent localized swelling as the result of vascular permeability and extravasation.
  - target: Facial Edema
    causal_link_type: DIRECT
    description: Localized vascular leakage can manifest as facial angioedema.
    evidence:
    - reference: PMID:42253962
      reference_title: "Acquired angioedema due to C1 inhibitor deficiency: real-world clinical characteristics and treatment outcomes."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        The most frequently affected sites were the face (90%; lips 80%),
        followed by the abdomen (80%) and the extremities (70%).
      explanation: The small AAE-C1-INH cohort documents facial involvement without assigning a disease-wide frequency.
  - target: Laryngeal Edema
    causal_link_type: DIRECT
    description: Localized upper-airway leakage can produce life-threatening laryngeal edema.
    evidence:
    - reference: PMID:30866985
      reference_title: "Angioedema due to acquired C1-inhibitor deficiency: spectrum and treatment with C1-inhibitor concentrate."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Acquired angioedema due to C1-inhibitor (C1-INH) deficiency
        (AAE-C1-INH) is a serious condition that may result in life-threatening
        asphyxiation due to laryngeal edema.
      explanation: The clinical cohort directly links AAE-C1-INH with dangerous laryngeal edema.
  - target: Abdominal Angioedema
    causal_link_type: DIRECT
    description: Localized submucosal leakage can manifest as abdominal angioedema.
    evidence:
    - reference: PMID:42253962
      reference_title: "Acquired angioedema due to C1 inhibitor deficiency: real-world clinical characteristics and treatment outcomes."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        The most frequently affected sites were the face (90%; lips 80%),
        followed by the abdomen (80%) and the extremities (70%).
      explanation: The small AAE-C1-INH cohort documents abdominal involvement without overclaiming pain or assigning a disease-wide frequency.
  - target: Peripheral Edema
    causal_link_type: DIRECT
    description: Localized vascular leakage can manifest as extremity or peripheral edema.
    evidence:
    - reference: PMID:42253962
      reference_title: "Acquired angioedema due to C1 inhibitor deficiency: real-world clinical characteristics and treatment outcomes."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        The most frequently affected sites were the face (90%; lips 80%),
        followed by the abdomen (80%) and the extremities (70%).
      explanation: The small cohort documents extremity involvement without assigning a disease-wide frequency.
phenotypes:
- category: Dermatologic
  name: Recurrent Angioedema
  description: >-
    Recurrent swelling affects subcutaneous or submucosal tissues without
    wheals and resolves between attacks.
  phenotype_term:
    preferred_term: angioedema
    term:
      id: HP:0100665
      label: Angioedema
    temporality: RECURRENT
  evidence:
  - reference: PMID:28284781
    reference_title: "Diagnosis, Course, and Management of Angioedema in Patients With Acquired C1-Inhibitor Deficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Diagnostic criteria included history of recurrent angioedema without
      wheals; decreased C1-INH antigen levels and/or functional activity of
      C1-INH and C4 antigen less than 50% of normal; late symptom onset (>40
      years); no family history of angioedema and C1-INH deficiency.
    explanation: The clinical criteria directly support recurrent angioedema without wheals.
- category: Craniofacial
  name: Facial Edema
  description: Facial swelling is a common site of AAE-C1-INH attacks.
  phenotype_term:
    preferred_term: facial edema
    term:
      id: HP:0000282
      label: Facial edema
    temporality: RECURRENT
  evidence:
  - reference: PMID:42253962
    reference_title: "Acquired angioedema due to C1 inhibitor deficiency: real-world clinical characteristics and treatment outcomes."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The most frequently affected sites were the face (90%; lips 80%),
      followed by the abdomen (80%) and the extremities (70%).
    explanation: The small cohort documents facial swelling without generalizing a frequency band across all patients.
- category: Respiratory
  name: Laryngeal Edema
  description: Upper-airway or laryngeal swelling can cause life-threatening asphyxiation.
  phenotype_term:
    preferred_term: laryngeal edema
    term:
      id: HP:0012027
      label: Laryngeal edema
    temporality: RECURRENT
    severity: SEVERE
  evidence:
  - reference: PMID:30866985
    reference_title: "Angioedema due to acquired C1-inhibitor deficiency: spectrum and treatment with C1-inhibitor concentrate."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Acquired angioedema due to C1-inhibitor (C1-INH) deficiency
      (AAE-C1-INH) is a serious condition that may result in life-threatening
      asphyxiation due to laryngeal edema.
    explanation: The cohort directly supports the dangerous laryngeal manifestation.
- category: Gastrointestinal
  name: Abdominal Angioedema
  description: >-
    Submucosal or intestinal edema can produce abdominal attacks. The cited
    cohort establishes abdominal involvement but is not used to infer a
    disease-wide pain frequency.
  phenotype_term:
    preferred_term: intestinal edema
    term:
      id: HP:0005225
      label: Intestinal edema
    temporality: RECURRENT
  evidence:
  - reference: PMID:42253962
    reference_title: "Acquired angioedema due to C1 inhibitor deficiency: real-world clinical characteristics and treatment outcomes."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The most frequently affected sites were the face (90%; lips 80%),
      followed by the abdomen (80%) and the extremities (70%).
    explanation: The small cohort supports abdominal angioedema, represented with the closest specific HPO edema term.
- category: Dermatologic
  name: Peripheral Edema
  description: Extremity or peripheral swelling occurs during localized attacks.
  phenotype_term:
    preferred_term: peripheral edema
    term:
      id: HP:0012398
      label: Peripheral edema
    temporality: RECURRENT
  evidence:
  - reference: PMID:42253962
    reference_title: "Acquired angioedema due to C1 inhibitor deficiency: real-world clinical characteristics and treatment outcomes."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The most frequently affected sites were the face (90%; lips 80%),
      followed by the abdomen (80%) and the extremities (70%).
    explanation: The small cohort supports extremity involvement and the HPO term is specific to peripheral edema.
biochemical:
- name: Low C1 Inhibitor Function
  presence: DECREASED
  context: >-
    Reduced functional C1-INH is the central laboratory abnormality. Antigen
    concentration may also be low, but functional and antigenic measurements
    are not interchangeable.
  biomarker_term:
    preferred_term: plasma protease C1 inhibitor
    term:
      id: NCIT:C181692
      label: Plasma Protease C1 Inhibitor
  readouts:
  - target: Acquired C1 Inhibitor Functional Deficiency
    relationship: READOUT_OF
    direction: NEGATIVE
    endpoint_context: DIAGNOSTIC
    interpretation: Reduced C1-INH function directly reports the defining functional-deficiency mechanism.
    evidence:
    - reference: PMID:33472202
      reference_title: "Acquired Angioedema with C1 Inhibitor Deficiency: Occurrence, Clinical Features, and Management: A Nationwide Retrospective Study in the Czech Republic Patients."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        The inclusion criteria involved recurrent episodes of angioedema with
        the first manifestation at or after the age of 40, negative family
        history of angioedema, and C1 inhibitor function 50% or less.
      explanation: The cohort uses reduced function as a direct disease-defining readout.
  evidence:
  - reference: PMID:33472202
    reference_title: "Acquired Angioedema with C1 Inhibitor Deficiency: Occurrence, Clinical Features, and Management: A Nationwide Retrospective Study in the Czech Republic Patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The inclusion criteria involved recurrent episodes of angioedema with the
      first manifestation at or after the age of 40, negative family history of
      angioedema, and C1 inhibitor function 50% or less.
    explanation: The cohort explicitly required low C1-INH function.
- name: Low C4
  presence: DECREASED
  context: >-
    Low C4 is a complement-consumption readout used with C1-INH function,
    antigen, and clinical context. It is not modeled as the mediator of edema.
  biomarker_term:
    preferred_term: complement component C4
    term:
      id: NCIT:C70618
      label: Complement Component-4
  readouts:
  - target: Acquired C1 Inhibitor Functional Deficiency
    relationship: CORRELATES_WITH
    direction: NEGATIVE
    endpoint_context: DIAGNOSTIC
    interpretation: Lower C4 correlates with the complement-consumption pattern accompanying acquired C1-INH deficiency.
    evidence:
    - reference: PMID:28284781
      reference_title: "Diagnosis, Course, and Management of Angioedema in Patients With Acquired C1-Inhibitor Deficiency."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Diagnostic criteria included history of recurrent angioedema without
        wheals; decreased C1-INH antigen levels and/or functional activity of
        C1-INH and C4 antigen less than 50% of normal; late symptom onset (>40
        years); no family history of angioedema and C1-INH deficiency.
      explanation: The cohort includes low C4 in the acquired C1-INH-deficiency diagnostic pattern.
  evidence:
  - reference: PMID:28284781
    reference_title: "Diagnosis, Course, and Management of Angioedema in Patients With Acquired C1-Inhibitor Deficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Diagnostic criteria included history of recurrent angioedema without
      wheals; decreased C1-INH antigen levels and/or functional activity of
      C1-INH and C4 antigen less than 50% of normal; late symptom onset (>40
      years); no family history of angioedema and C1-INH deficiency.
    explanation: Low C4 is part of the cohort's combined diagnostic criteria.
- name: Low or Undetectable C1q
  presence: DECREASED
  context: >-
    Low C1q supports an acquired C1-INH-deficiency pattern but is not specific
    by itself and should not be treated as an exclusionary requirement.
  biomarker_term:
    preferred_term: complement component C1q
    term:
      id: NCIT:C193256
      label: Complement Component C1q
  readouts:
  - target: Acquired C1 Inhibitor Functional Deficiency
    relationship: CORRELATES_WITH
    direction: NEGATIVE
    endpoint_context: DIAGNOSTIC
    interpretation: Low C1q correlates with, but does not uniquely identify, acquired C1-INH deficiency.
    evidence:
    - reference: PMID:31397881
      reference_title: Serum complexes between C1INH and C1INH autoantibodies for the diagnosis of acquired angioedema.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        When free antiC1INHAbs and malignant tumors are not detectable,
        diagnosis relies on the finding of low C1INH levels and/or function,
        lack of family history and SERPING1 mutations, age at onset and low or
        undetectable C1q levels, none of which is specific for AAE.
      explanation: The source supports the C1q association and explicitly preserves its lack of specificity.
  evidence:
  - reference: PMID:32753245
    reference_title: "[Acquired angioedema due to C1-inhibitor deficiency: CREAK recommendations for diagnosis and treatment]."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Low C1q is observed in 90% of patients, and an anti C1-inhibitor antibody is found in 50% of patients."
    explanation: The recommendations summarize how often these supportive findings were observed.
- name: C1-INH-Anti-C1-INH Immune Complexes
  presence: PRESENT
  context: >-
    Circulating C1-INH/anti-C1-INH complexes can improve detection when free
    antibodies are not measurable. They are represented as a specialized
    diagnostic biomarker, not as a proven causal node.
  readouts:
  - target: Anti-C1-INH Autoantibody-Mediated Inactivation
    relationship: CORRELATES_WITH
    direction: PRESENT_ABSENT
    endpoint_context: DIAGNOSTIC
    interpretation: Complex detection supports an anti-C1-INH antibody-associated disease context but does not prove that the measured complexes cause deficiency.
    evidence:
    - reference: PMID:31397881
      reference_title: Serum complexes between C1INH and C1INH autoantibodies for the diagnosis of acquired angioedema.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        C1INH-antiC1INHAb complexes were found in 18 of 20 of the AAE cases,
        regardless of the presence or absence of detectable free
        anti-C1INHAbs.
      explanation: The cohort establishes a diagnostic correlation without assigning causal force to the complexes.
  evidence:
  - reference: PMID:31397881
    reference_title: Serum complexes between C1INH and C1INH autoantibodies for the diagnosis of acquired angioedema.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Of note, nine of 20 patients showed negative free antiC1INHabs, but
      positive C1INH-antiC1INHAb complexes in their first measurement.
    explanation: Complex testing can detect an antibody-associated pattern when free antibodies are negative.
diagnosis:
- name: Complement and C1-INH Antigenic and Functional Testing
  description: >-
    Evaluate recurrent angioedema without wheals using C4, C1-INH antigen, and
    C1-INH function, then interpret C1q, age, family history, and genetic
    findings in combination. Functional and antigenic assays should both be
    considered because concentration alone can miss functional deficiency.
  results: >-
    Low C1-INH function with low antigen and/or C4 supports C1-INH-deficiency
    angioedema. Low C1q supports the acquired form, but no single laboratory or
    historical feature is specific on its own.
  evidence:
  - reference: PMID:34956216
    reference_title: "Angioedema Without Wheals: Challenges in Laboratorial Diagnosis."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Diagnosis is established by nephelometry, turbidimetry, or radial
      immunodiffusion for quantitative measurement of C1 inhibitor, and
      chromogenic assay or ELISA has been used for functional C1-INH analysis.
    explanation: The diagnostic review identifies quantitative and functional assay approaches.
  - reference: PMID:31397881
    reference_title: Serum complexes between C1INH and C1INH autoantibodies for the diagnosis of acquired angioedema.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      When free antiC1INHAbs and malignant tumors are not detectable, diagnosis
      relies on the finding of low C1INH levels and/or function, lack of family
      history and SERPING1 mutations, age at onset and low or undetectable C1q
      levels, none of which is specific for AAE.
    explanation: The source supports a combined interpretation and cautions against treating any component as specific alone.
- name: Specialized Anti-C1-INH Antibody and Immune-Complex Testing
  description: >-
    Free anti-C1-INH antibody testing can support the acquired diagnosis.
    C1-INH/anti-C1-INH complex assays may add information in specialist or
    research settings, especially when free antibody testing is negative, but
    are not represented as a universal standalone diagnostic test.
  results: >-
    Detection of free anti-C1-INH antibodies or C1-INH/anti-C1-INH complexes
    supports an antibody-associated AAE-C1-INH context.
  evidence:
  - reference: PMID:32753245
    reference_title: "[Acquired angioedema due to C1-inhibitor deficiency: CREAK recommendations for diagnosis and treatment]."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Low C1q is observed in 90% of patients, and an anti C1-inhibitor antibody is found in 50% of patients."
    explanation: The recommendations identify anti-C1-INH antibodies as a frequent supportive finding.
  - reference: PMID:36726161
    reference_title: C1-inhibitor/C1-inhibitor antibody complexes in acquired angioedema due to C1-inhibitor deficiency.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Measurement of CAC is recommended to be done parallelly with C1-INH-Ab,
      so as to detect both free and bound antibodies.
    explanation: A specialist cohort recommends parallel complex and free-antibody measurement, but broader clinical utility remains unsettled.
- name: Evaluation and Surveillance for an Associated Clonal Disorder
  description: >-
    Evaluate for an associated hematologic or monoclonal disorder and continue
    longitudinal reassessment when initial studies are unrevealing, because
    angioedema can precede recognition of the underlying condition.
  results: >-
    Identification of lymphoma, another clonal hematologic neoplasm, or
    monoclonal gammopathy can explain the associated disease context and guide
    etiology-directed management.
  evidence:
  - reference: PMID:39756409
    reference_title: A multi-centre UK-based survey on angioedema secondary to acquired C1 inhibitor deficiency.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "A haematological disorder was identified in 83.8% of AAE-C1-INH patients compared to 3.4% of autoimmune diseases."
    explanation: The UK survey supports systematic evaluation for an associated hematologic disorder.
  - reference: PMID:42253962
    reference_title: "Acquired angioedema due to C1 inhibitor deficiency: real-world clinical characteristics and treatment outcomes."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Clonal hematologic neoplasms were present in 60% of patients and
      monoclonal gammopathy of undetermined significance in 30%, with
      angioedema preceding the diagnosis of the underlying condition in 60% of
      cases.
    explanation: The 2026 cohort shows why continued surveillance can matter after angioedema presentation.
treatments:
- name: Plasma-Derived C1 Inhibitor Concentrate
  description: >-
    Plasma-derived C1-INH concentrate is used as on-demand treatment for acute
    AAE-C1-INH attacks. Observational data show high attack-level effectiveness,
    although response and required dose can vary, particularly with
    anti-C1-INH antibodies.
  therapeutic_modality: PROTEIN_REPLACEMENT
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: human C1-esterase inhibitor
      term:
        id: NCIT:C87730
        label: Human C1-Esterase Inhibitor
  target_mechanisms:
  - target: Acquired C1 Inhibitor Functional Deficiency
    treatment_effect: RESTORES
    description: Exogenous C1-INH supplies inhibitor activity at the defining deficient node.
    evidence:
    - reference: PMID:30866985
      reference_title: "Angioedema due to acquired C1-inhibitor deficiency: spectrum and treatment with C1-inhibitor concentrate."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "A total of 3553 (97.7%) of the 3636 attacks were effectively treated with pdC1-INH as assessed by the patient."
      explanation: Clinical response supports target engagement, while restoration of inhibitor activity is a replacement-therapy inference.
  evidence:
  - reference: PMID:30866985
    reference_title: "Angioedema due to acquired C1-inhibitor deficiency: spectrum and treatment with C1-inhibitor concentrate."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "A total of 3553 (97.7%) of the 3636 attacks were effectively treated with pdC1-INH as assessed by the patient."
    explanation: The large attack-level cohort supports plasma-derived C1-INH for on-demand treatment.
- name: Recombinant C1 Inhibitor Concentrate
  description: >-
    Recombinant C1-INH is an alternative replacement option used for acute
    attacks. The available AAE cohort reports response to recombinant or
    plasma-derived concentrate without separating product-specific outcomes.
  therapeutic_modality: PROTEIN_REPLACEMENT
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: conestat alfa
      term:
        id: NCIT:C96366
        label: Conestat Alfa
  target_mechanisms:
  - target: Acquired C1 Inhibitor Functional Deficiency
    treatment_effect: RESTORES
    description: Recombinant C1-INH supplies inhibitor activity at the defining deficient node.
    evidence:
    - reference: PMID:33472202
      reference_title: "Acquired Angioedema with C1 Inhibitor Deficiency: Occurrence, Clinical Features, and Management: A Nationwide Retrospective Study in the Czech Republic Patients."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "All patients responded to the acute attack treatment with icatibant and plasma-derived or recombinant C1 inhibitor concentrate."
      explanation: The pooled cohort supports replacement at this node but does not isolate recombinant-product response.
  evidence:
  - reference: PMID:33472202
    reference_title: "Acquired Angioedema with C1 Inhibitor Deficiency: Occurrence, Clinical Features, and Management: A Nationwide Retrospective Study in the Czech Republic Patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "All patients responded to the acute attack treatment with icatibant and plasma-derived or recombinant C1 inhibitor concentrate."
    explanation: The cohort includes recombinant C1-INH among effective acute treatments but reports products in aggregate.
- name: Icatibant On-Demand Therapy
  description: >-
    Icatibant is a bradykinin B2-receptor antagonist used on demand for acute
    AAE-C1-INH attacks.
  therapeutic_modality: PEPTIDE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: icatibant
      term:
        id: CHEBI:68556
        label: icatibant
  target_mechanisms:
  - target: Bradykinin B2-Receptor Signaling
    treatment_effect: INHIBITS
    description: Icatibant antagonizes the B2 receptor that mediates a major component of permeability signaling.
    evidence:
    - reference: PMID:19796797
      reference_title: Novel pathogenic mechanism and therapeutic approaches to angioedema associated with C1 inhibitor deficiency.
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "This finding has led to the development of novel therapeutic drugs such as the B2 receptor antagonist icatibant."
      explanation: The mechanistic paper explicitly identifies icatibant as a B2-receptor antagonist.
  evidence:
  - reference: PMID:33472202
    reference_title: "Acquired Angioedema with C1 Inhibitor Deficiency: Occurrence, Clinical Features, and Management: A Nationwide Retrospective Study in the Czech Republic Patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "All patients responded to the acute attack treatment with icatibant and plasma-derived or recombinant C1 inhibitor concentrate."
    explanation: The national cohort supports acute-attack response to icatibant.
- name: Tranexamic Acid Long-Term Prophylaxis
  description: >-
    Tranexamic acid is a specialist long-term prophylactic option. Cohort
    responses are heterogeneous, and the available caches do not justify a
    specific causal target edge to C1-INH deficiency or the contact system.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: tranexamic acid
      term:
        id: CHEBI:48669
        label: tranexamic acid
  evidence:
  - reference: PMID:28284781
    reference_title: "Diagnosis, Course, and Management of Angioedema in Patients With Acquired C1-Inhibitor Deficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Thirty-four patients received long-term prophylaxis with tranexamic acid (effective in 29)"
    explanation: The Milan cohort reports benefit in most treated patients.
  - reference: PMID:42253962
    reference_title: "Acquired angioedema due to C1 inhibitor deficiency: real-world clinical characteristics and treatment outcomes."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Antifibrinolytic agents showed limited efficacy, whereas attenuated androgens were associated with a marked reduction in attack frequency."
    explanation: A small 2026 cohort illustrates heterogeneous prophylactic response.
- name: Emerging Off-Label Berotralstat Prophylaxis
  description: >-
    Berotralstat is a plasma-kallikrein inhibitor with only a three-patient
    AAE-C1-INH subgroup in the available real-world report. It is represented
    as emerging, off-label, and PARTIAL evidence rather than core established
    care.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: berotralstat
      term:
        id: NCIT:C169808
        label: Berotralstat
  target_mechanisms:
  - target: Bradykinin-Mediated Attack Signaling
    treatment_effect: INHIBITS
    description: Plasma-kallikrein inhibition is expected to reduce bradykinin generation.
    evidence:
    - reference: PMID:35212456
      reference_title: Population pharmacokinetic modeling and simulations of berotralstat for prophylactic treatment of attacks of hereditary angioedema.
      supports: SUPPORT
      evidence_source: COMPUTATIONAL
      snippet: >-
        Berotralstat is a potent, highly selective, orally bioavailable
        small-molecule plasma kallikrein inhibitor that has been approved to
        prevent attacks of HAE in adults and children 12 years of age and
        older.
      explanation: The source establishes the molecular target in HAE; transfer to AAE-C1-INH is mechanistic extrapolation.
  evidence:
  - reference: PMID:37914894
    reference_title: A Retrospective Analysis of Long-Term Prophylaxis with Berotralstat in Patients with Hereditary Angioedema and Acquired C1-Inhibitor Deficiency-Real-World Data.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      After 6 months of treatment, a median decrease of attacks per month was
      noted for HAE type I patients (3.3 to 1.5) and AAE-C1-INH patients (2.3
      to 1.0).
    explanation: The outcome is encouraging but derives from only three AAE-C1-INH patients.
- name: Treat the Associated Lymphoproliferative or Monoclonal Disorder
  description: >-
    Etiology-directed management of an associated lymphoma, other clonal
    hematologic disease, or monoclonal gammopathy can reduce angioedema activity
    and may normalize complement parameters.
  treatment_term:
    preferred_term: therapeutic procedure
    term:
      id: NCIT:C49236
      label: Therapeutic Procedure
  target_mechanisms:
  - target: Clonal B-Cell or Monoclonal Gammopathy-Associated C1-INH Consumption
    treatment_effect: MODULATES
    description: Controlling the associated disorder can reduce the upstream disease context that sustains AAE-C1-INH.
    evidence:
    - reference: PMID:33472202
      reference_title: "Acquired Angioedema with C1 Inhibitor Deficiency: Occurrence, Clinical Features, and Management: A Nationwide Retrospective Study in the Czech Republic Patients."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        In 6 of 7 patients (86%) treated for lymphoma, either a reduction in the
        frequency of angioedema attacks or both angioedema symptoms'
        disappearance and complement parameter normalization was observed.
      explanation: Clinical improvement after lymphoma treatment supports an upstream etiology-directed strategy.
  evidence:
  - reference: PMID:33472202
    reference_title: "Acquired Angioedema with C1 Inhibitor Deficiency: Occurrence, Clinical Features, and Management: A Nationwide Retrospective Study in the Czech Republic Patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      In 6 of 7 patients (86%) treated for lymphoma, either a reduction in the
      frequency of angioedema attacks or both angioedema symptoms'
      disappearance and complement parameter normalization was observed.
    explanation: The cohort supports treating the associated lymphoid malignancy as a primary disease-control strategy.
- name: Rituximab-Based B-Cell-Directed Therapy
  description: >-
    Rituximab-based therapy is an observationally supported, etiology-directed
    option, particularly for clonal B-cell or lymphoid-malignancy-associated
    AAE-C1-INH. Selection requires specialist hematology/immunology oversight;
    prophylactic standard of care remains unsettled.
  therapeutic_modality: MONOCLONAL_ANTIBODY
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: rituximab
      term:
        id: NCIT:C1702
        label: Rituximab
  target_mechanisms:
  - target: Clonal B-Cell or Monoclonal Gammopathy-Associated C1-INH Consumption
    treatment_effect: MODULATES
    description: B-cell-directed treatment can control the associated clonal context and reduce angioedema activity.
    evidence:
    - reference: PMID:39756409
      reference_title: A multi-centre UK-based survey on angioedema secondary to acquired C1 inhibitor deficiency.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Rituximab monotherapy was effective in treating 9/9 splenic marginal zone lymphoma and 1/2 MGUS-associated AAE-C1-INH."
      explanation: The observational response supports the target relationship but does not establish a universal prophylactic standard.
  evidence:
  - reference: PMID:37844846
    reference_title: Efficacy and Safety of Rituximab-Based Treatments in Angioedema With Acquired C1-Inhibitor Deficiency.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Rituximab is an efficient and well-tolerated therapeutic option in AE, especially in lymphoid malignancies and in the absence of detectable anti-C1-INH antibodies."
    explanation: The 55-patient multicenter study supports rituximab-based treatment, with subgroup-dependent response.
  - reference: PMID:39756409
    reference_title: A multi-centre UK-based survey on angioedema secondary to acquired C1 inhibitor deficiency.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "B cell depletion could be considered in treating monoclonal B cell disorder-associated-AAE-C1-INH in the absence of haematological indications."
    explanation: The UK survey supports cautious consideration even when standard hematologic indications are absent.
- name: C1-INH Short-Term Prophylaxis Before Procedures
  description: >-
    C1-INH concentrate has been used shortly before invasive diagnostic or
    therapeutic procedures in AAE-C1-INH. The available evidence is a small
    observational cohort.
  therapeutic_modality: PROTEIN_REPLACEMENT
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: human C1-esterase inhibitor
      term:
        id: NCIT:C87730
        label: Human C1-Esterase Inhibitor
  target_mechanisms:
  - target: Acquired C1 Inhibitor Functional Deficiency
    treatment_effect: RESTORES
    description: Pre-procedure concentrate transiently supplies C1-INH activity at the deficient node.
    evidence:
    - reference: PMID:42253962
      reference_title: "Acquired angioedema due to C1 inhibitor deficiency: real-world clinical characteristics and treatment outcomes."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Short-term prophylaxis with C1-INH concentrate at a dose of 1000 IU was administered to 6 patients (60%) one hour prior to"
      explanation: The small cohort documents pre-procedure use; restoration remains a replacement-therapy inference.
  evidence:
  - reference: PMID:42253962
    reference_title: "Acquired angioedema due to C1 inhibitor deficiency: real-world clinical characteristics and treatment outcomes."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Short-term prophylaxis with C1-INH concentrate at a dose of 1000 IU was administered to 6 patients (60%) one hour prior to"
    explanation: The source documents short-term prophylactic use before procedures in a small cohort.
  - reference: PMID:42253962
    reference_title: "Acquired angioedema due to C1 inhibitor deficiency: real-world clinical characteristics and treatment outcomes."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "invasive diagnostic and/or therapeutic procedures, and no AE attacks were observed during or after these procedures."
    explanation: No peri-procedural attacks were observed in the treated cohort, but the sample was small and uncontrolled.
clinical_trials:
- name: NCT06818474
  phase: PHASE_IV
  status: RECRUITING
  description: >-
    Open-label Phase IV interventional study evaluating lanadelumab for
    long-term prophylaxis in acquired angioedema.
  target_phenotypes:
  - preferred_term: angioedema
    term:
      id: HP:0100665
      label: Angioedema
  notes: >-
    ClinicalTrials.gov returned RECRUITING on 2026-07-19 with estimated
    enrollment of 5. The registry record's own verification date was February
    2025, so recruitment status warrants continued rechecking. No AAE efficacy
    claim is inferred.
  evidence:
  - reference: clinicaltrials:NCT06818474
    reference_title: Lanadelumab in Long-term Prophylaxis of Acquired Angioedema
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: use of lanadelumab in patients with acquired angioedema
    explanation: The registry summary establishes the AAE lanadelumab study.
- name: NCT07266805
  phase: PHASE_III
  status: RECRUITING
  description: >-
    Randomized Phase III study evaluating deucrictibant XR for prophylaxis and
    deucrictibant IR for on-demand treatment of attacks in adults with
    AAE-C1-INH.
  target_phenotypes:
  - preferred_term: angioedema
    term:
      id: HP:0100665
      label: Angioedema
  notes: >-
    ClinicalTrials.gov returned RECRUITING on 2026-07-19 with estimated
    enrollment of 32 and a record update posted 2026-06-29. A prior
    randomized crossover study enrolled only three patients, so deucrictibant
    remains investigational for AAE-C1-INH.
  evidence:
  - reference: clinicaltrials:NCT07266805
    reference_title: "A Phase 3, Randomized, Double-blind, Placebo-controlled, 3-Part Study to Evaluate the Efficacy and Safety of Orally Administered Deucrictibant Extended-release (XR) Tablet for Prophylaxis and Deucrictibant Immediate-release (IR) Capsule for On-demand Treatment of Angioedema Attacks in Adults With Acquired Angioedema Due to C1 Inhibitor Deficiency"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      This is a Phase 3, multicenter, 3-part study, with 2 randomized,
      double-blind, placebo-controlled parts and an open-label extension part,
      to evaluate the efficacy and safety of orally administered deucrictibant
      XR tablet for prophylaxis, and deucrictibant IR capsule for on-demand
      treatment of angioedema attacks in adult participants aged ≥ 18 years with
      AAE-C1INH.
    explanation: The registry summary establishes the phase, design, population, and investigational uses.
  - reference: PMID:38494092
    reference_title: "Deucrictibant for angioedema due to acquired C1-inhibitor deficiency: A randomized-controlled trial."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Three patients were enrolled; of those 3 patients, 1 completed both study parts and 2 completed only Part 2."
    explanation: The prior randomized crossover evidence is limited to three patients.
differential_diagnoses:
- name: Hereditary Angioedema with C1 Inhibitor Deficiency
  disease_term:
    preferred_term: hereditary angioedema with C1 inhibitor deficiency
    term:
      id: MONDO:0019623
      label: hereditary angioedema
  description: >-
    HAE-C1-INH can produce an indistinguishable bradykinin-mediated attack
    pattern and low C1-INH. Family history, earlier onset, and a pathogenic
    SERPING1 finding favor hereditary disease, but de novo or late-presenting
    HAE means no single feature is decisive.
  distinguishing_features:
  - A family history, earlier onset, or a pathogenic SERPING1 finding favors HAE-C1-INH.
  - Later onset, low C1q, an associated clonal disorder, or anti-C1-INH antibodies supports AAE-C1-INH, but these features must be interpreted together.
  evidence:
  - reference: PMID:42253962
    reference_title: "Acquired angioedema due to C1 inhibitor deficiency: real-world clinical characteristics and treatment outcomes."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Acquired angioedema due to C1 inhibitor deficiency (AAE-C1INH) is a rare bradykinin-mediated condition that may mimic hereditary angioedema (HAE)."
    explanation: The recent cohort explicitly identifies HAE as a clinical mimic.
  - reference: PMID:42165046
    reference_title: "The 2025 WAO Guidelines for the classification, diagnosis, and treatment of hereditary angioedema, with consideration of worldwide disparities."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      The diagnostic strategy emphasizes early clinical recognition based on
      characteristic features, including recurrent angioedema without
      urticaria, abdominal or laryngeal involvement, early symptom onset, and
      family history.
    explanation: The HAE guideline supports early onset and family history as characteristic hereditary clues.
  - reference: PMID:31397881
    reference_title: Serum complexes between C1INH and C1INH autoantibodies for the diagnosis of acquired angioedema.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      When free antiC1INHAbs and malignant tumors are not detectable, diagnosis
      relies on the finding of low C1INH levels and/or function, lack of family
      history and SERPING1 mutations, age at onset and low or undetectable C1q
      levels, none of which is specific for AAE.
    explanation: The source supplies the acquired clues while warning that none is individually specific.
- name: Hereditary Angioedema with Normal C1 Inhibitor
  description: >-
    HAE with normal C1-INH can produce recurrent bradykinin-mediated attacks but
    lacks the defining low C1-INH antigen/function pattern of AAE-C1-INH.
  distinguishing_features:
  - Normal complement and C1-INH assays argue against acquired C1-INH deficiency.
  - Family history and targeted genetic evaluation can support a normal-C1-INH hereditary form.
  evidence:
  - reference: PMID:34956216
    reference_title: "Angioedema Without Wheals: Challenges in Laboratorial Diagnosis."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Regarding HAE with normal C1 inhibitor, complement assays' results are
      normal and the genetic sequencing of target genes, such as exon 9 of F12
      and PLG, is the only available method.
    explanation: The review distinguishes normal-C1-INH hereditary disease through normal complement assays and genetic evaluation.
- name: ACE Inhibitor- or RAS-Blocker-Associated Angioedema
  description: >-
    Medication-associated angioedema can mimic or coexist with AAE-C1-INH.
    Exposure alone must not terminate the complement and C1-INH evaluation when
    recurrent bradykinin-mediated attacks suggest an additional cause.
  distinguishing_features:
  - Review the timing of ACE inhibitor or other renin-angiotensin-system blocker exposure.
  - Low C1-INH function and the acquired complement pattern support AAE-C1-INH even when a relevant medication exposure is present.
  evidence:
  - reference: PMID:42253962
    reference_title: "Acquired angioedema due to C1 inhibitor deficiency: real-world clinical characteristics and treatment outcomes."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Two patients developed AE episodes in association with ACE inhibitor or
      ARB exposure and were subsequently found to have AAE-C1INH.
    explanation: The cohort demonstrates that RAS-blocker exposure and AAE-C1-INH can coexist.
- name: Mast-Cell-Mediated Angioedema or Chronic Spontaneous Urticaria
  description: >-
    Mast-cell-mediated angioedema and chronic spontaneous urticaria can include
    recurrent swelling but belong to a different mechanistic endotype from
    acquired C1-INH-deficiency angioedema.
  distinguishing_features:
  - Recurrent itchy wheals with or without angioedema favor chronic spontaneous urticaria and mast-cell activation.
  - Recurrent angioedema without wheals together with low C1-INH function and complement consumption favors AAE-C1-INH.
  evidence:
  - reference: PMID:31899843
    reference_title: Evidence for bradykinin release in chronic spontaneous urticaria.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Chronic spontaneous urticaria (CSU) is characterized by recurrent itchy weals and/or angioedema and is believed to be driven by mast cell activation."
    explanation: The study states the wheal/itch and mast-cell pattern that distinguishes CSU from the focal disease.
  - reference: PMID:38670233
    reference_title: "Definition, acronyms, nomenclature, and classification of angioedema (DANCE): AAAAI, ACAAI, ACARE, and APAAACI DANCE consensus."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      AE is heterogeneous, can be hereditary or acquired, may occur only once
      or be recurrent, may exhibit wheals or not, and may be due to mast cell
      mediators, bradykinin, or other mechanisms.
    explanation: The consensus classification supports separating mast-cell and bradykinin endotypes.
notes: |
  Scope is restricted to acquired angioedema caused by acquired C1 inhibitor
  deficiency. Historical AAE type I/type II labels are not modeled as mutually
  exclusive subtypes because consumption, clonal disease, and anti-C1-INH
  autoantibodies can overlap.

  No therapy is approved specifically for AAE-C1-INH in the cited cohorts.
  Acute airway compromise is an emergency; treatment selection and long-term
  prophylaxis require specialist care. C1-INH concentrate and icatibant have the
  strongest AAE-specific acute observational support. Rituximab and treatment
  of an associated clonal disorder are etiology-directed options supported by
  observational cohorts. Tranexamic acid response is heterogeneous, berotralstat
  evidence is limited to a three-patient AAE subgroup, and lanadelumab and
  deucrictibant remain investigational in the listed trials.

  No disease-specific public molecular dataset or experimental model was added
  in this review; omission is not evidence that none exists.
references:
- reference: PMID:19796797
  title: Novel pathogenic mechanism and therapeutic approaches to angioedema associated with C1 inhibitor deficiency.
  findings: []
- reference: PMID:28284781
  title: "Diagnosis, Course, and Management of Angioedema in Patients With Acquired C1-Inhibitor Deficiency."
  findings: []
- reference: PMID:30866985
  title: "Angioedema due to acquired C1-inhibitor deficiency: spectrum and treatment with C1-inhibitor concentrate."
  findings: []
- reference: PMID:31397881
  title: Serum complexes between C1INH and C1INH autoantibodies for the diagnosis of acquired angioedema.
  findings: []
- reference: PMID:31899843
  title: Evidence for bradykinin release in chronic spontaneous urticaria.
  findings: []
- reference: PMID:32753245
  title: "[Acquired angioedema due to C1-inhibitor deficiency: CREAK recommendations for diagnosis and treatment]."
  findings: []
- reference: PMID:33472202
  title: "Acquired Angioedema with C1 Inhibitor Deficiency: Occurrence, Clinical Features, and Management: A Nationwide Retrospective Study in the Czech Republic Patients."
  findings: []
- reference: PMID:34956216
  title: "Angioedema Without Wheals: Challenges in Laboratorial Diagnosis."
  findings: []
- reference: PMID:35212456
  title: Population pharmacokinetic modeling and simulations of berotralstat for prophylactic treatment of attacks of hereditary angioedema.
  findings: []
- reference: PMID:36726161
  title: C1-inhibitor/C1-inhibitor antibody complexes in acquired angioedema due to C1-inhibitor deficiency.
  findings: []
- reference: PMID:37844846
  title: Efficacy and Safety of Rituximab-Based Treatments in Angioedema With Acquired C1-Inhibitor Deficiency.
  findings: []
- reference: PMID:37914894
  title: A Retrospective Analysis of Long-Term Prophylaxis with Berotralstat in Patients with Hereditary Angioedema and Acquired C1-Inhibitor Deficiency-Real-World Data.
  findings: []
- reference: PMID:38494092
  title: "Deucrictibant for angioedema due to acquired C1-inhibitor deficiency: A randomized-controlled trial."
  findings: []
- reference: PMID:38670233
  title: "Definition, acronyms, nomenclature, and classification of angioedema (DANCE): AAAAI, ACAAI, ACARE, and APAAACI DANCE consensus."
  findings: []
- reference: PMID:39756409
  title: A multi-centre UK-based survey on angioedema secondary to acquired C1 inhibitor deficiency.
  findings: []
- reference: PMID:42165046
  title: "The 2025 WAO Guidelines for the classification, diagnosis, and treatment of hereditary angioedema, with consideration of worldwide disparities."
  findings: []
- reference: PMID:42253962
  title: "Acquired angioedema due to C1 inhibitor deficiency: real-world clinical characteristics and treatment outcomes."
  findings: []
- reference: PMID:9508789
  title: "Mechanism of action of anti-C1-inhibitor autoantibodies: prevention of the formation of stable C1s-C1-inh complexes."
  findings: []
- reference: clinicaltrials:NCT06818474
  title: Lanadelumab in Long-term Prophylaxis of Acquired Angioedema
  findings: []
- reference: clinicaltrials:NCT07266805
  title: "A Phase 3, Randomized, Double-blind, Placebo-controlled, 3-Part Study to Evaluate the Efficacy and Safety of Orally Administered Deucrictibant Extended-release (XR) Tablet for Prophylaxis and Deucrictibant Immediate-release (IR) Capsule for On-demand Treatment of Angioedema Attacks in Adults With Acquired Angioedema Due to C1 Inhibitor Deficiency"
  findings: []
📚

References & Deep Research

References

20
PMID:19796797
Novel pathogenic mechanism and therapeutic approaches to angioedema associated with C1 inhibitor deficiency.
No top-level findings curated for this source.
PMID:28284781
Diagnosis, Course, and Management of Angioedema in Patients With Acquired C1-Inhibitor Deficiency.
No top-level findings curated for this source.
PMID:30866985
Angioedema due to acquired C1-inhibitor deficiency: spectrum and treatment with C1-inhibitor concentrate.
No top-level findings curated for this source.
PMID:31397881
Serum complexes between C1INH and C1INH autoantibodies for the diagnosis of acquired angioedema.
No top-level findings curated for this source.
PMID:31899843
Evidence for bradykinin release in chronic spontaneous urticaria.
No top-level findings curated for this source.
PMID:32753245
[Acquired angioedema due to C1-inhibitor deficiency: CREAK recommendations for diagnosis and treatment].
No top-level findings curated for this source.
PMID:33472202
Acquired Angioedema with C1 Inhibitor Deficiency: Occurrence, Clinical Features, and Management: A Nationwide Retrospective Study in the Czech Republic Patients.
No top-level findings curated for this source.
PMID:34956216
Angioedema Without Wheals: Challenges in Laboratorial Diagnosis.
No top-level findings curated for this source.
PMID:35212456
Population pharmacokinetic modeling and simulations of berotralstat for prophylactic treatment of attacks of hereditary angioedema.
No top-level findings curated for this source.
PMID:36726161
C1-inhibitor/C1-inhibitor antibody complexes in acquired angioedema due to C1-inhibitor deficiency.
No top-level findings curated for this source.
PMID:37844846
Efficacy and Safety of Rituximab-Based Treatments in Angioedema With Acquired C1-Inhibitor Deficiency.
No top-level findings curated for this source.
PMID:37914894
A Retrospective Analysis of Long-Term Prophylaxis with Berotralstat in Patients with Hereditary Angioedema and Acquired C1-Inhibitor Deficiency-Real-World Data.
No top-level findings curated for this source.
PMID:38494092
Deucrictibant for angioedema due to acquired C1-inhibitor deficiency: A randomized-controlled trial.
No top-level findings curated for this source.
PMID:38670233
Definition, acronyms, nomenclature, and classification of angioedema (DANCE): AAAAI, ACAAI, ACARE, and APAAACI DANCE consensus.
No top-level findings curated for this source.
PMID:39756409
A multi-centre UK-based survey on angioedema secondary to acquired C1 inhibitor deficiency.
No top-level findings curated for this source.
PMID:42165046
The 2025 WAO Guidelines for the classification, diagnosis, and treatment of hereditary angioedema, with consideration of worldwide disparities.
No top-level findings curated for this source.
PMID:42253962
Acquired angioedema due to C1 inhibitor deficiency: real-world clinical characteristics and treatment outcomes.
No top-level findings curated for this source.
PMID:9508789
Mechanism of action of anti-C1-inhibitor autoantibodies: prevention of the formation of stable C1s-C1-inh complexes.
No top-level findings curated for this source.
clinicaltrials:NCT06818474
Lanadelumab in Long-term Prophylaxis of Acquired Angioedema
No top-level findings curated for this source.
clinicaltrials:NCT07266805
A Phase 3, Randomized, Double-blind, Placebo-controlled, 3-Part Study to Evaluate the Efficacy and Safety of Orally Administered Deucrictibant Extended-release (XR) Tablet for Prophylaxis and Deucrictibant Immediate-release (IR) Capsule for On-demand Treatment of Angioedema Attacks in Adults With Acquired Angioedema Due to C1 Inhibitor Deficiency
No top-level findings curated for this source.

Deep Research

1
Falcon ▸
1. Disease Information
Edison Scientific Literature 26 citations 2026-05-10T12:59:14.510639

1. Disease Information

1.1 Concise overview (current understanding)

Acquired angioedema due to C1-inhibitor deficiency (AAE-C1-INH; also written AAE-C1INH or C1-INH-AAE) is a rare, non-hereditary, bradykinin-mediated angioedema characterized by recurrent episodes of subcutaneous and/or submucosal swelling that may involve the face, tongue/oral cavity, gastrointestinal tract, and upper airway, with potential for fatal laryngeal edema. It is defined by acquired deficiency or dysfunction of C1 inhibitor (C1-INH) with accompanying complement abnormalities and typically occurs in adults with no family history. (bork2019angioedemadueto pages 1-2, sobotkova2021acquiredangioedemawith pages 1-2, grumach2021angioedemawithoutwheals pages 2-3)

1.2 Common synonyms / alternative names

  • Acquired angioedema due to C1-inhibitor deficiency (AAE-C1-INH) (sobotkova2021acquiredangioedemawith pages 1-2, bork2019angioedemadueto pages 1-2)
  • Acquired C1-inhibitor deficiency (johnson2023aretrospectiveanalysis pages 1-2)
  • C1-INH-AAE (polai2023c1inhibitorc1inhibitorantibodycomplexes pages 1-2)

1.3 Key identifiers (availability in retrieved sources)

  • MONDO: MONDO:0019624 (OpenTargets mapping) (OpenTargets Search: Acquired angioedema)
  • Other identifiers requested (ICD-10/ICD-11, Orphanet, MeSH, OMIM): Not retrievable from the currently collected tool evidence; this report therefore does not assert specific ICD/Orphanet/MeSH/OMIM codes.

1.4 Evidence source types

The information in this report is derived primarily from aggregated disease-level resources (national cohort studies, referral-center cohorts, peer-reviewed reviews) and clinical trial registry records, rather than EHR-only sources. (sobotkova2021acquiredangioedemawith pages 1-2, bork2019angioedemadueto pages 1-2, NCT07266805 chunk 1)

2. Etiology

2.1 Primary causes (mechanistic)

AAE-C1-INH arises from secondary (acquired) C1-INH deficiency, resulting from (i) consumption of C1-INH and complement components (often driven by B-cell lymphoproliferation) and/or (ii) autoantibody-mediated inactivation of C1-INH. These processes lead to dysregulated activation of complement/contact systems and excess bradykinin, increasing vascular permeability and causing angioedema. (johnson2023aretrospectiveanalysis pages 1-2, bork2019angioedemadueto pages 1-2, grumach2021angioedemawithoutwheals pages 2-3)

2.2 Risk factors / associated conditions (high-confidence)

AAE-C1-INH is strongly associated with B-cell lymphoproliferative disorders and monoclonal gammopathies, and can also be associated with autoimmune disease.

Quantitative association data from cohorts: - Czech nationwide cohort (n=14): lymphoid malignancy 64% (9/14); MGUS 21% (3/14); autoimmune disease 7% (1/14); none identified 7% (1/14). (sobotkova2021acquiredangioedemawith pages 1-2) - Mainz referral cohort (n=44): MGUS 47.7%; non-Hodgkin lymphoma 27.3%; anti-C1-INH autoantibodies alone 11.4%; no associated disorder 9.1%. (bork2019angioedemadueto pages 1-2)

2.3 Triggers and precipitating factors

Triggers reported include mechanical trauma, emotional stress, and ACE inhibitors (as potential triggers/complicating exposures in bradykinin-mediated disease contexts). (polai2023c1inhibitorc1inhibitorantibodycomplexes pages 1-2)

2.4 Protective factors and gene–environment interactions

No protective factors or gene–environment interaction evidence specific to AAE-C1-INH were found in the retrieved tool evidence. Given that AAE-C1-INH is typically secondary and non-hereditary, genetic susceptibility is not generally the primary driver (contrast with hereditary angioedema). (sobotkova2021acquiredangioedemawith pages 1-2, grumach2021angioedemawithoutwheals pages 2-3)

3. Phenotypes

3.1 Clinical phenotype spectrum and frequencies

AAE-C1-INH commonly presents with recurrent non-urticarial swelling affecting facial/oropharyngeal tissues, airway, abdomen, and extremities. In a Czech nationwide series (n=14), phenotype frequencies were: - Facial edema: 100% (14/14) - Upper airway involvement: 85.7% (12/14) - Abdominal attacks: 50% (7/14) - Peripheral angioedema: 42.8% (6/14) (sobotkova2021acquiredangioedemawith pages 4-5)

Disease onset in this cohort occurred between 40–82 years (median 59.5). (sobotkova2021acquiredangioedemawith pages 4-5)

3.2 Phenotype characteristics

  • Age of onset: Typically adult-onset, often >40 years; cohort median near 60 years. (sobotkova2021acquiredangioedemawith pages 1-2, sobotkova2021acquiredangioedemawith pages 4-5)
  • Course pattern: Episodic attacks.
  • Severity: Potentially life-threatening due to airway involvement. (bork2019angioedemadueto pages 1-2)

3.3 Quality-of-life (QoL) impact

Direct AAE-C1-INH QoL data in the retrieved evidence are limited; however, a small real-world prophylaxis series that included AAE-C1-INH patients reported improvement in angioedema-specific QoL and control measures with berotralstat (see Treatment section). (johnson2023aretrospectiveanalysis pages 1-2)

3.4 Suggested HPO terms (non-exhaustive)

Based on the above cohort phenotypes: - Angioedema: HP:0100664 - Facial swelling: HP:0000280 - Laryngeal edema / upper airway edema: HP:0011106 (laryngeal edema) / HP:0011107 (airway edema; term usage varies) - Abdominal pain (during abdominal attacks): HP:0002027 - Edema of extremities: HP:0000969

(sobotkova2021acquiredangioedemawith pages 4-5)

4. Genetic / Molecular Information

4.1 Causal genes and variants

AAE-C1-INH is not primarily a germline genetic disorder; it is defined by an acquired deficiency/dysfunction of C1-INH rather than inherited SERPING1 mutations. In diagnostic frameworks, lack of SERPING1 mutation supports acquired disease when combined with late onset and complement patterns. (grumach2021angioedemawithoutwheals pages 2-3, caballero2022medicalalgorithmmanagement pages 2-2)

4.2 Autoantibodies and immune complexes (key molecular entities)

Anti–C1-INH autoantibodies may be present as free antibodies or in immune complexes, which has diagnostic implications: - In a European AAE cohort (n=20), free anti-C1INHAbs were detected in 9/20, while C1INH–antiC1INHAb complexes were detected in 18/20; notably 9/20 were negative for free antibodies but positive for complexes at first measurement. (lopezlera2019serumcomplexesbetween pages 1-2) - A Hungarian center cohort (n=19) reported 79% with an underlying disease and recommended measuring C1-INH/C1-INH antibody complexes (CAC) in parallel with free antibody testing for improved detection and monitoring. (polai2023c1inhibitorc1inhibitorantibodycomplexes pages 1-2)

4.3 Suggested CHEBI entities (therapeutic-relevant)

  • Bradykinin: CHEBI:15883 (central mediator; evidence of bradykinin-mediated mechanism from reviews/algorithms) (bork2019angioedemadueto pages 1-2, grumach2021angioedemawithoutwheals pages 2-3)

5. Environmental Information

5.1 Environmental/lifestyle factors

No population-level environmental or lifestyle risk factor evidence specific to AAE-C1-INH was captured in the retrieved documents.

5.2 Drug-related triggers

ACE inhibitors are mentioned as potential triggers/associations in the context of bradykinin-mediated angioedema and can confound diagnosis; AAE-C1-INH has specific complement abnormalities that help distinguish it. (polai2023c1inhibitorc1inhibitorantibodycomplexes pages 1-2)

6. Mechanism / Pathophysiology

6.1 Causal chain (trigger → mediator → phenotype)

  1. Underlying B-cell lymphoproliferation/MGUS and/or autoantibodies leads to consumption or inactivation of C1-INH. (sobotkova2021acquiredangioedemawith pages 1-2, bork2019angioedemadueto pages 1-2, johnson2023aretrospectiveanalysis pages 1-2)
  2. Reduced functional C1-INH permits dysregulated activation of complement/contact systems, increasing downstream generation of bradykinin. (grumach2021angioedemawithoutwheals pages 2-3, bork2019angioedemadueto pages 1-2)
  3. Bradykinin increases vascular permeability, producing episodic submucosal/subcutaneous edema (angioedema), including potentially fatal laryngeal edema. (bork2019angioedemadueto pages 1-2, grumach2021angioedemawithoutwheals pages 2-3)

6.2 Upstream vs downstream

  • Upstream: Underlying disease (lymphoproliferative, MGUS, autoimmune), anti–C1-INH antibodies/complexes, complement consumption (low C1q suggests classical pathway involvement). (sobotkova2021acquiredangioedemawith pages 1-2, bork2019angioedemadueto pages 1-2, lopezlera2019serumcomplexesbetween pages 1-2)
  • Downstream: Bradykinin-mediated permeability and tissue swelling; failure to respond to histamine-directed therapies is a practical downstream clinical discriminator in reviews/algorithms. (falco2025orofacialangioedemaan pages 3-5, caballero2022medicalalgorithmmanagement pages 2-2)

6.3 Suggested GO Biological Process terms (examples)

  • Complement activation, classical pathway: GO:0006958 (supported by complement consumption patterns, low C1q) (sobotkova2021acquiredangioedemawith pages 4-5, grumach2021angioedemawithoutwheals pages 2-3)
  • Regulation of blood vessel permeability: GO:0008217 (bradykinin-mediated edema phenotype) (bork2019angioedemadueto pages 1-2)

6.4 Suggested Cell Ontology (CL) terms (best-effort)

Because many associations are B-cell/monoclonal gammopathy driven: - B cell: CL:0000236 - Plasma cell: CL:0000786

(sobotkova2021acquiredangioedemawith pages 1-2, bork2019angioedemadueto pages 1-2)

7. Anatomical Structures Affected

7.1 Primary anatomical sites and systems (with UBERON suggestions)

From cohort phenotype data, commonly affected sites include: - Face: UBERON:0001456 (sobotkova2021acquiredangioedemawith pages 4-5) - Upper airway/larynx: UBERON:0001737 (larynx) (sobotkova2021acquiredangioedemawith pages 4-5, bork2019angioedemadueto pages 1-2) - Gastrointestinal tract (bowel): UBERON:0001555 (digestive tract) / UBERON:0002108 (small intestine) (abdominal attacks) (sobotkova2021acquiredangioedemawith pages 4-5) - Extremities/limbs: UBERON:0002101 (limb) (sobotkova2021acquiredangioedemawith pages 4-5)

8. Temporal Development

8.1 Onset and course

AAE-C1-INH typically has adult onset (>40 years), often late middle age, and follows an episodic course with recurrent attacks. In the Czech nationwide cohort, the median onset age was 59.5 years and diagnosis delay median 1 year. (sobotkova2021acquiredangioedemawith pages 1-2)

8.2 Remission patterns

Treating underlying lymphoproliferative disease can reduce attack frequency and may normalize complement parameters (reported as an observation in the Czech cohort summary). (sobotkova2021acquiredangioedemawith pages 1-2)

9. Inheritance and Population

9.1 Inheritance pattern

AAE-C1-INH is acquired and therefore not inherited in a Mendelian fashion; it is differentiated from hereditary angioedema by lack of family history and lack of SERPING1 mutation in diagnostic algorithms. (grumach2021angioedemawithoutwheals pages 2-3, caballero2022medicalalgorithmmanagement pages 2-2)

9.2 Epidemiology (statistics)

Best-available prevalence estimates from retrieved sources: - Czech Republic nationwide retrospective study: prevalence ~1:760,000; AAE-C1-INH accounted for ~8% of angioedema with C1-INH deficiency in that setting. (sobotkova2021acquiredangioedemawith pages 1-2) - Literature estimates: 1:100,000–1:500,000 inhabitants. (bork2019angioedemadueto pages 1-2, lopezlera2019serumcomplexesbetween pages 1-2) - A recent real-world prophylaxis paper cites prevalence ~0.15 per 100,000. (johnson2023aretrospectiveanalysis pages 1-2)

Sex distribution in Czech cohort was 7 male / 7 female (1:1). (sobotkova2021acquiredangioedemawith pages 4-5)

10. Diagnostics

10.1 Core diagnostic laboratory tests (complement/C1-INH panel)

A practical and widely referenced pattern for AAE-C1-INH is: - Low C4 - Low C1-INH functional activity - Low C1-INH antigen (often) - Low C1q (frequent, helpful to differentiate acquired from hereditary forms) - Anti–C1-INH autoantibodies and/or C1-INH–anti–C1-INH immune complexes in many cases

Czech cohort laboratory frequencies provide concrete performance-like data: - Low C4: 14/14 (100%) - Low C1-INH function: 14/14 (100%) - Low C1-INH antigen: 13/14 (93%) - Low C1q: 10/14 (71.4%) (sobotkova2021acquiredangioedemawith pages 4-5)

A review focused on laboratory differentiation summarizes the pattern as AAE-C1-INH having low C1-INH function and concentration, low C4, low C1q, and frequently anti–C1-INH antibodies, without SERPING1 mutation. (grumach2021angioedemawithoutwheals pages 2-3)

10.2 Antibody/complex testing as a diagnostic enhancer (recent development)

A key 2019 development is demonstration that immune-complex detection may be more sensitive than free antibody detection: C1INH–antiC1INHAb complexes were found in 18/20 AAE cases even when free antibodies were negative (9/20). (lopezlera2019serumcomplexesbetween pages 1-2) A 2023 Orphanet Journal paper further argues CAC measurements can aid prediction/monitoring of underlying disease and recommends parallel measurement with free antibody. (polai2023c1inhibitorc1inhibitorantibodycomplexes pages 1-2)

10.3 Differential diagnosis (high-level)

  • Hereditary angioedema due to C1-INH deficiency (HAE types I/II): similar clinical phenotype but typically earlier onset and normal C1q; SERPING1 variants may be present. (grumach2021angioedemawithoutwheals pages 2-3, caballero2022medicalalgorithmmanagement pages 2-2)
  • Histaminergic angioedema: tends to respond to antihistamines/corticosteroids/epinephrine; complement panel typically normal. (falco2025orofacialangioedemaan pages 3-5, caballero2022medicalalgorithmmanagement pages 2-2)
  • ACE inhibitor–associated angioedema: bradykinin-mediated but lacks the characteristic complement abnormalities; diagnosis is clinical/exclusion. (grumach2021angioedemawithoutwheals pages 2-3)

10.4 Suggested LOINC-style test names (best-effort)

(Exact LOINC codes were not available in retrieved evidence; below are standardized test concepts commonly used clinically.) - Complement C4 [Mass/volume] in Serum/Plasma (C4) - C1 esterase inhibitor [Mass/volume] in Serum/Plasma (C1-INH antigen) - C1 esterase inhibitor activity in Serum/Plasma (C1-INH function) - Complement C1q [Mass/volume] in Serum/Plasma (C1q) - Anti–C1-INH antibody (IgG/IgM) in Serum; and/or C1-INH–anti–C1-INH immune complexes (ELISA-based) (lopezlera2019serumcomplexesbetween pages 1-2, polai2023c1inhibitorc1inhibitorantibodycomplexes pages 1-2)

11. Outcome / Prognosis

11.1 Morbidity and mortality considerations

AAE-C1-INH can be life-threatening due to laryngeal edema/asphyxiation risk. (bork2019angioedemadueto pages 1-2)

11.2 Prognostic factors (inferred from cohort observations)

  • Presence and treatability of an underlying lymphoproliferative disorder is clinically important; treating lymphoma was associated with reduced angioedema activity and complement normalization in a Czech cohort summary. (sobotkova2021acquiredangioedemawith pages 1-2)

Robust survival rates, mortality rates, or long-term disability estimates were not present in the retrieved tool evidence.

12. Treatment

12.1 Current applications and real-world implementations

No therapies are universally approved specifically for AAE-C1-INH in many jurisdictions; clinical practice often uses HAE-directed therapies off-label. (johnson2023aretrospectiveanalysis pages 1-2, bork2019angioedemadueto pages 1-2)

On-demand (acute attack) treatments

  • Plasma-derived C1-INH concentrate (pdC1-INH): In a 44-patient referral cohort, pdC1-INH was reported effective in 3553/3636 attacks (97.7%) and shortened attack duration by 54.4 ± 32.8 hours on average; effectiveness remained high even in anti–C1-INH antibody-positive patients (93.8% effectiveness). (bork2019angioedemadueto pages 1-2)
  • Icatibant (bradykinin B2 receptor antagonist): In Czech cohort, icatibant was used (n=8) and reported efficient in all treated cases. (sobotkova2021acquiredangioedemawith pages 4-5)
  • Recombinant C1-INH: used acutely in Czech cohort (n=4), efficient in all treated cases. (sobotkova2021acquiredangioedemawith pages 4-5)

Long-term prophylaxis and disease control (recent evidence; 2023 focus)

  • Berotralstat (oral plasma kallikrein inhibitor): A 2023 real-world retrospective series included 3 AAE-C1-INH patients; after 6 months, median attacks/month decreased from 2.3 to 1.0, with AE-QoL improvement of 13.7 points and AECT increase of 4.2 points. (johnson2023aretrospectiveanalysis pages 1-2)
  • Tranexamic acid (TA): In Czech cohort, long-term prophylaxis was started in 9/14; TA was used in 5, and was effective as a single agent in 2/5. (sobotkova2021acquiredangioedemawith pages 4-5)

Treating underlying disease (mechanism-directed upstream therapy)

Because AAE-C1-INH is commonly associated with lymphoproliferative disease/MGUS, evaluation and treatment of the underlying disorder is a core real-world strategy, with cohort observations of attack reduction and complement normalization after lymphoma treatment. (sobotkova2021acquiredangioedemawith pages 1-2)

12.2 Experimental / clinical trials (recent developments; 2024–2026 registry data)

  • Lanadelumab in long-term prophylaxis of acquired angioedema (NCT06818474): Phase 4, open-label, single-group study; inclusion specifies recurrent AAE without urticaria plus labs consistent with acquired C1-INH deficiency (decreased C1INH functional/quantitative, decreased C4, decreased C1q, no family history, anti-C1INH Ab and/or paraproteinemia). Start date 2024-06-01; first posted 2025-02-10. URL: https://clinicaltrials.gov/ct2/show/NCT06818474 (NCT06818474 chunk 1)
  • Deucrictibant (oral bradykinin B2 receptor antagonist) for AAE-C1INH (NCT07266805, “CREAATE”): Phase 3 randomized placebo-controlled multi-part study testing XR prophylaxis and IR on-demand treatment; start date 2025-10-16; first posted 2025-12-05; last update 2026-05-07. URL: https://clinicaltrials.gov/study/NCT07266805 (NCT07266805 chunk 1)

12.3 Suggested MAXO terms (examples; best-effort)

  • C1 esterase inhibitor replacement therapy (pdC1-INH/rhC1-INH) (bork2019angioedemadueto pages 1-2, sobotkova2021acquiredangioedemawith pages 4-5)
  • Bradykinin receptor antagonist therapy (icatibant; and oral B2 antagonist under trial) (sobotkova2021acquiredangioedemawith pages 4-5, NCT07266805 chunk 1)
  • Kallikrein inhibitor therapy (berotralstat; lanadelumab) (johnson2023aretrospectiveanalysis pages 1-2, NCT06818474 chunk 1)
  • Antifibrinolytic therapy (tranexamic acid) (sobotkova2021acquiredangioedemawith pages 4-5)
  • Treatment of underlying lymphoproliferative disease (sobotkova2021acquiredangioedemawith pages 1-2, bork2019angioedemadueto pages 1-2)

13. Prevention

13.1 Prevention levels

  • Primary prevention: Not well-defined because AAE-C1-INH is typically secondary to underlying conditions rather than preventable exposures.
  • Secondary/tertiary prevention: Key strategy is early recognition of bradykinin-mediated angioedema, confirmation with complement testing, and preventing airway compromise through rapid access to effective on-demand therapy; additionally, identifying/treating underlying lymphoproliferative disease can reduce recurrence. (sobotkova2021acquiredangioedemawith pages 1-2, bork2019angioedemadueto pages 1-2)

Short-term procedural prophylaxis is discussed in broader angioedema management reviews (not AAE-specific in the retrieved evidence), but AAE patients are often managed analogously to HAE in practice where clinically justified. (caballero2022medicalalgorithmmanagement pages 2-2)

14. Other Species / Natural Disease

No evidence for naturally occurring AAE-C1-INH as a defined disease entity in other species was identified in the retrieved evidence. AAE-C1-INH is primarily a human secondary immunologic/hematologic syndrome.

15. Model Organisms

The retrieved evidence did not include specific in vivo models of acquired C1-INH deficiency angioedema. Mechanistic work in bradykinin/complement biology often uses complement/contact system models, but explicit AAE-C1-INH model-organism validation was not present in the collected sources.

Key quantitative facts table (for knowledge base ingestion)

Topic Key details (quantitative where available) Best supporting sources (with year, journal, DOI/URL) Notes
Acquired Angioedema (AAE-C1-INH) key facts — definition Rare, non-hereditary, bradykinin-mediated angioedema caused by acquired C1-inhibitor deficiency; clinically similar to hereditary C1-INH deficiency; may cause life-threatening laryngeal edema/asphyxiation. Typically lacks family history and SERPING1 mutation. (bork2019angioedemadueto pages 1-2, grumach2021angioedemawithoutwheals pages 2-3) Sobotkova et al., 2021, Int Arch Allergy Immunol, doi:10.1159/000512933, https://doi.org/10.1159/000512933 (sobotkova2021acquiredangioedemawith pages 1-2); Bork et al., 2019, Orphanet J Rare Dis, doi:10.1186/s13023-019-1043-3, https://doi.org/10.1186/s13023-019-1043-3 (bork2019angioedemadueto pages 1-2); Grumach et al., 2021, Front Immunol, doi:10.3389/fimmu.2021.785736, https://doi.org/10.3389/fimmu.2021.785736 (grumach2021angioedemawithoutwheals pages 2-3) Aggregated disease-level literature, not individual EHR-derived definitions.
Typical onset Adult onset, usually after age 40; Czech nationwide cohort median symptom onset 59.5 years (range 40–82). Diagnostic delay in Czech cohort: median 1 year. (sobotkova2021acquiredangioedemawith pages 1-2, sobotkova2021acquiredangioedemawith pages 4-5) Sobotkova et al., 2021, Int Arch Allergy Immunol, doi:10.1159/000512933, https://doi.org/10.1159/000512933 (sobotkova2021acquiredangioedemawith pages 1-2, sobotkova2021acquiredangioedemawith pages 4-5); Johnson et al., 2023, Clin Rev Allergy Immunol, doi:10.1007/s12016-023-08972-2, https://doi.org/10.1007/s12016-023-08972-2 (johnson2023aretrospectiveanalysis pages 1-2) Later onset is a major clue distinguishing AAE from hereditary disease.
Core lab pattern Typical pattern: low C1-INH function, low/usually low C1-INH antigen, low C4, and often low C1q. In Czech cohort: low C4 14/14 (100%), low C1-INH function 14/14 (100%), low C1-INH antigen 13/14 (93%), low C1q 10/14 (71.4%). Anti-C1-INH antibodies are frequent but not universal. (sobotkova2021acquiredangioedemawith pages 4-5, grumach2021angioedemawithoutwheals pages 2-3) Sobotkova et al., 2021, Int Arch Allergy Immunol, doi:10.1159/000512933, https://doi.org/10.1159/000512933 (sobotkova2021acquiredangioedemawith pages 4-5); Grumach et al., 2021, Front Immunol, doi:10.3389/fimmu.2021.785736, https://doi.org/10.3389/fimmu.2021.785736 (grumach2021angioedemawithoutwheals pages 2-3); López-Lera et al., 2019, Clin Exp Immunol, doi:10.1111/cei.13361, https://doi.org/10.1111/cei.13361 (lopezlera2019serumcomplexesbetween pages 1-2) Low C1q helps distinguish AAE-C1-INH from HAE-C1-INH, though exceptions exist.
Associated conditions — Czech cohort Underlying disease in 13/14 (93%): lymphoid malignancy 9/14 (64%), MGUS 3/14 (21%), autoimmune disease 1/14 (7%), no underlying disease 1/14 (7%). (sobotkova2021acquiredangioedemawith pages 1-2) Sobotkova et al., 2021, Int Arch Allergy Immunol, doi:10.1159/000512933, https://doi.org/10.1159/000512933 (sobotkova2021acquiredangioedemawith pages 1-2) Supports strong need to investigate lymphoproliferative and autoimmune disorders.
Associated conditions — Bork cohort In 44-patient cohort: MGUS 47.7%, non-Hodgkin lymphoma 27.3%, anti-C1-INH autoantibodies alone 11.4%, other conditions 4.5%, no associated disorder 9.1%. AAE led to lymphoma detection in 75% of patients with malignancy. (bork2019angioedemadueto pages 1-2) Bork et al., 2019, Orphanet J Rare Dis, doi:10.1186/s13023-019-1043-3, https://doi.org/10.1186/s13023-019-1043-3 (bork2019angioedemadueto pages 1-2) One of the most quantitative cohort summaries for associated disorders.
Prevalence / occurrence estimates Ultra-rare. Reported prevalence estimates: ~1:760,000 in Czech Republic; literature estimate 1:100,000 to 1:500,000; one review cites ~0.15 per 100,000. AAE-C1-INH represented ~8% of angioedema with C1-INH deficiency in the Czech study. (sobotkova2021acquiredangioedemawith pages 1-2, johnson2023aretrospectiveanalysis pages 1-2, lopezlera2019serumcomplexesbetween pages 1-2) Sobotkova et al., 2021, Int Arch Allergy Immunol, doi:10.1159/000512933, https://doi.org/10.1159/000512933 (sobotkova2021acquiredangioedemawith pages 1-2); Johnson et al., 2023, Clin Rev Allergy Immunol, doi:10.1007/s12016-023-08972-2, https://doi.org/10.1007/s12016-023-08972-2 (johnson2023aretrospectiveanalysis pages 1-2); López-Lera et al., 2019, Clin Exp Immunol, doi:10.1111/cei.13361, https://doi.org/10.1111/cei.13361 (lopezlera2019serumcomplexesbetween pages 1-2) Incidence estimates are sparse; prevalence usually inferred from national or referral-center cohorts.
Phenotype frequencies — Czech cohort Facial edema 14/14 (100%); upper airway involvement 12/14 (85.7%); abdominal attacks 7/14 (50%); peripheral angioedema 6/14 (42.8%). (sobotkova2021acquiredangioedemawith pages 4-5) Sobotkova et al., 2021, Int Arch Allergy Immunol, doi:10.1159/000512933, https://doi.org/10.1159/000512933 (sobotkova2021acquiredangioedemawith pages 4-5) Facial and airway attacks were especially prominent in this cohort.
Antibody / immune-complex detection European cohort (n=20): free anti-C1INH antibodies detected in 9/20 (45%); C1INH–anti-C1INH immune complexes detected in 18/20 (90%); 9/20 were negative for free antibodies but positive for complexes at first measurement. Hungarian cohort (n=19): 79% had an underlying disease; 11/19 had detectable anti-C1-INH antibodies at least once. (lopezlera2019serumcomplexesbetween pages 1-2, polai2023c1inhibitorc1inhibitorantibodycomplexes pages 1-2) López-Lera et al., 2019, Clin Exp Immunol, doi:10.1111/cei.13361, https://doi.org/10.1111/cei.13361 (lopezlera2019serumcomplexesbetween pages 1-2); Polai et al., 2023, Orphanet J Rare Dis, doi:10.1186/s13023-023-02625-5, https://doi.org/10.1186/s13023-023-02625-5 (polai2023c1inhibitorc1inhibitorantibodycomplexes pages 1-2) Measuring complexes alongside free antibody may improve diagnostic yield and monitoring.
Acute treatment effectiveness Plasma-derived C1-INH (pdC1-INH) was effective in 3553/3636 attacks (97.7%) and shortened attacks by mean 54.4 ± 32.8 hours; effectiveness in anti-C1-INH autoantibody-positive patients was 1246/1329 attacks (93.8%). Czech cohort: icatibant (n=8), pdC1-INH/Berinert (n=4), and recombinant C1-INH (n=4) were all reported effective in all treated cases. (bork2019angioedemadueto pages 7-8, sobotkova2021acquiredangioedemawith pages 4-5, bork2019angioedemadueto pages 1-2) Bork et al., 2019, Orphanet J Rare Dis, doi:10.1186/s13023-019-1043-3, https://doi.org/10.1186/s13023-019-1043-3 (bork2019angioedemadueto pages 7-8, bork2019angioedemadueto pages 1-2); Sobotkova et al., 2021, Int Arch Allergy Immunol, doi:10.1159/000512933, https://doi.org/10.1159/000512933 (sobotkova2021acquiredangioedemawith pages 4-5) No therapies are specifically approved for AAE-C1-INH in many regions; use is often extrapolated from HAE.
Prophylaxis / QoL real-world data Berotralstat real-world series included 3 AAE-C1-INH patients. After 6 months, median attacks/month fell from 2.3 to 1.0; no aerodigestive attacks were noted; mean AE-QoL improved by 13.7 points; AECT increased by 4.2 points. (johnson2023aretrospectiveanalysis pages 1-2) Johnson et al., 2023, Clin Rev Allergy Immunol, doi:10.1007/s12016-023-08972-2, https://doi.org/10.1007/s12016-023-08972-2 (johnson2023aretrospectiveanalysis pages 1-2) Small sample, off-label use, but among the most relevant recent 2023 real-world AAE prophylaxis/QoL data.

Table: This table summarizes the main clinical, laboratory, epidemiologic, and treatment facts for acquired angioedema due to C1-inhibitor deficiency using only the gathered evidence. It highlights quantitative cohort findings and recent real-world treatment data that are particularly useful for a disease knowledge base.

Expert opinion and analysis (synthesis of authoritative sources)

  1. Diagnostic emphasis: Multiple authoritative reviews/algorithms converge on the idea that AAE-C1-INH is best recognized by combining clinical context (late onset, no family history) with a complement/C1-INH laboratory panel including C1q and optional anti–C1-INH testing; however, these markers can show exceptions, so repeated testing and comprehensive evaluation for underlying B-cell disease are often required. (grumach2021angioedemawithoutwheals pages 2-3, caballero2022medicalalgorithmmanagement pages 2-2, sobotkova2021acquiredangioedemawith pages 4-5)
  2. Recent methodological refinement (2023): Measuring C1-INH/anti–C1-INH complexes (CAC) in parallel with free antibodies is a notable 2023 development aimed at improving detection and potentially monitoring underlying disease evolution. (polai2023c1inhibitorc1inhibitorantibodycomplexes pages 1-2)
  3. Treatment reality: Despite the absence of universally approved AAE-specific therapies, real-world cohort data support high effectiveness of pdC1-INH for acute attacks, and emerging prophylaxis approaches (e.g., oral kallikrein inhibition with berotralstat) show promising reductions in attack rate and improved patient-reported outcomes in small AAE subsets. (bork2019angioedemadueto pages 1-2, johnson2023aretrospectiveanalysis pages 1-2)

Notes on citation requirements (PMID availability)

Several retrieved sources did not include PMIDs in the text snippets available to the tool; therefore, this report provides DOIs/URLs and publication dates from the retrieved metadata, and does not fabricate PMIDs.

References

  1. (OpenTargets Search: Acquired angioedema): Open Targets Query (Acquired angioedema, 11 results). Buniello, A. et al. (2025). Open Targets Platform: facilitating therapeutic hypotheses building in drug discovery. Nucleic Acids Research.

  2. (bork2019angioedemadueto pages 1-2): Konrad Bork, Petra Staubach-Renz, and Jochen Hardt. Angioedema due to acquired c1-inhibitor deficiency: spectrum and treatment with c1-inhibitor concentrate. Orphanet Journal of Rare Diseases, Mar 2019. URL: https://doi.org/10.1186/s13023-019-1043-3, doi:10.1186/s13023-019-1043-3. This article has 68 citations and is from a peer-reviewed journal.

  3. (sobotkova2021acquiredangioedemawith pages 1-2): Marta Sobotkova, Radana Zachova, Roman Hakl, Pavel Kuklinek, Pavlina Kralickova, Irena Krcmova, Jana Hanzlikova, Martina Vachova, and Jirina Bartunkova. Acquired angioedema with c1 inhibitor deficiency: occurrence, clinical features, and management: a nationwide retrospective study in the czech republic patients. International Archives of Allergy and Immunology, 182:642-649, Jan 2021. URL: https://doi.org/10.1159/000512933, doi:10.1159/000512933. This article has 33 citations and is from a peer-reviewed journal.

  4. (grumach2021angioedemawithoutwheals pages 2-3): Anete S. Grumach, Camila L. Veronez, Dorottya Csuka, and Henriette Farkas. Angioedema without wheals: challenges in laboratorial diagnosis. Frontiers in Immunology, Dec 2021. URL: https://doi.org/10.3389/fimmu.2021.785736, doi:10.3389/fimmu.2021.785736. This article has 26 citations and is from a peer-reviewed journal.

  5. (johnson2023aretrospectiveanalysis pages 1-2): Felix Johnson, Anna Stenzl, Benedikt Hofauer, Helen Heppt, Eva-Vanessa Ebert, Barbara Wollenberg, Robin Lochbaum, Janina Hahn, Jens Greve, and Susanne Trainotti. A retrospective analysis of long-term prophylaxis with berotralstat in patients with hereditary angioedema and acquired c1-inhibitor deficiency—real-world data. Clinical Reviews in Allergy & Immunology, 65:354-364, Nov 2023. URL: https://doi.org/10.1007/s12016-023-08972-2, doi:10.1007/s12016-023-08972-2. This article has 14 citations and is from a peer-reviewed journal.

  6. (polai2023c1inhibitorc1inhibitorantibodycomplexes pages 1-2): Zsofia Polai, Erika Kajdacsi, Laszlo Cervenak, Zsuzsanna Balla, Szabolcs Benedek, Lilian Varga, and Henriette Farkas. C1-inhibitor/c1-inhibitor antibody complexes in acquired angioedema due to c1-inhibitor deficiency. Orphanet Journal of Rare Diseases, Feb 2023. URL: https://doi.org/10.1186/s13023-023-02625-5, doi:10.1186/s13023-023-02625-5. This article has 6 citations and is from a peer-reviewed journal.

  7. (NCT07266805 chunk 1): Study of Oral Deucrictibant XR Tablet for Prophylaxis and Deucrictibant IR Capsule for On-Demand Treatment of Angioedema Attacks in Adults With Acquired Angioedema Due to C1 Inhibitor Deficiency. Pharvaris Netherlands B.V.. 2025. ClinicalTrials.gov Identifier: NCT07266805

  8. (sobotkova2021acquiredangioedemawith pages 4-5): Marta Sobotkova, Radana Zachova, Roman Hakl, Pavel Kuklinek, Pavlina Kralickova, Irena Krcmova, Jana Hanzlikova, Martina Vachova, and Jirina Bartunkova. Acquired angioedema with c1 inhibitor deficiency: occurrence, clinical features, and management: a nationwide retrospective study in the czech republic patients. International Archives of Allergy and Immunology, 182:642-649, Jan 2021. URL: https://doi.org/10.1159/000512933, doi:10.1159/000512933. This article has 33 citations and is from a peer-reviewed journal.

  9. (caballero2022medicalalgorithmmanagement pages 2-2): Teresa Caballero, Rosario Cabañas, and María Pedrosa. Medical algorithm: management of c1 inhibitor hereditary angioedema. Allergy, 77:1060-1063, Oct 2022. URL: https://doi.org/10.1111/all.15115, doi:10.1111/all.15115. This article has 4 citations and is from a highest quality peer-reviewed journal.

  10. (lopezlera2019serumcomplexesbetween pages 1-2): A. López-Lera, S. Garrido, P. Nozal, Lillemor Skatum, A. Bygum, T. Caballero, and M. López Trascasa. Serum complexes between c1inh and c1inh autoantibodies for the diagnosis of acquired angioedema. Clinical & Experimental Immunology, 198:341-350, Dec 2019. URL: https://doi.org/10.1111/cei.13361, doi:10.1111/cei.13361. This article has 12 citations and is from a peer-reviewed journal.

  11. (falco2025orofacialangioedemaan pages 3-5): Domenico De Falco, Diego Misceo, Giuseppe Carretta, Gioele Gioco, Carlo Lajolo, and Massimo Petruzzi. Oro-facial angioedema: an overview. Immuno, 5:61, Dec 2025. URL: https://doi.org/10.3390/immuno5040061, doi:10.3390/immuno5040061. This article has 2 citations.

  12. (NCT06818474 chunk 1): Jonathan A. Bernstein, MD. Lanadelumab in Long-term Prophylaxis of Acquired Angioedema. Bernstein Clinical Research Center. 2024. ClinicalTrials.gov Identifier: NCT06818474

  13. (bork2019angioedemadueto pages 7-8): Konrad Bork, Petra Staubach-Renz, and Jochen Hardt. Angioedema due to acquired c1-inhibitor deficiency: spectrum and treatment with c1-inhibitor concentrate. Orphanet Journal of Rare Diseases, Mar 2019. URL: https://doi.org/10.1186/s13023-019-1043-3, doi:10.1186/s13023-019-1043-3. This article has 68 citations and is from a peer-reviewed journal.