Genomic coordinate (human 11:57,597,685 SERPING1) & (mouse 2:84,595,704 Serping1).
Cytoband (human 11q12.1 SERPING1) & (mouse 2qE1 Serping1).
Here I present: “Hereditary Angioedema”, Victor McKusick, Mendelian Inheritance in Man’, 1966. (SERPING1) icd10=D84.1
Icd10=84.1 — (Angioedema)
🧬 What’s actually happening?
Angioedema is sudden, localized swelling of deeper layers of skin and mucosa caused by leakage from small blood vessels into interstitial tissues.
Common sites:
Eyelids
Lips
Tongue
Face
Hands / feet
Larynx (⚠️ airway risk)
GI tract (can mimic an acute abdomen)
Unlike urticaria (hives), angioedema:
is deeper
often non-pruritic
may be painful or burning rather than itchy
🔗 Major Pathophysiologic Types
1. Histamine-mediated
Allergic reactions (foods, drugs, insect stings)
Often occurs with urticaria
Responds to:
antihistamines
corticosteroids
epinephrine
2. Bradykinin-mediated (the D84.1 “immunodeficiency” logic)
This is where complement biology kicks in:
Hereditary Angioedema (HAE)
↓ or dysfunctional C1 esterase inhibitor (C1-INH)
Mutations in SERPING1
Acquired C1-INH deficiency
e.g. lymphoproliferative disorders
ACE-inhibitor induced
↓ bradykinin breakdown
Key features:
No urticaria
Slower onset
Longer duration (2–5 days)
Poor response to antihistamines or steroids
Risk of laryngeal edema
🧪 Labs (especially if recurrent)
C4 ↓
C1-INH level
C1-INH functional assay
C1q (to distinguish hereditary vs acquired)
🚑 Clinical Red Flags
Voice change
Dysphagia
Stridor
Abdominal colic + vomiting
Family history of similar swelling
Airway involvement = medical emergency
💊 Targeted Treatments (Bradykinin-mediated)
C1-INH concentrate
Icatibant (B2 receptor antagonist)
Ecallantide (kallikrein inhibitor)
Fresh frozen plasma (in some settings).
There is evidence that hereditary angioedema is caused by mutation in the serine protease inhibitor-G1 (SERPING1) gene encoded on genomic coordinate 11:57,597,685 and cytoband in 11q12.1 humans.
