**Core Concept**
Hereditary angioneurotic edema (HAE) is a rare genetic disorder characterized by recurrent episodes of severe swelling, primarily affecting the skin and mucous membranes. This condition is caused by a deficiency or dysfunction of the C1 esterase inhibitor protein (C1INH), leading to uncontrolled activation of the complement system.

**Why the Correct Answer is Right**
HAE is primarily inherited in an autosomal dominant pattern, meaning a single copy of the mutated gene is sufficient to cause the condition. The disease is caused by mutations in the SERPING1 gene, which encodes the C1INH protein. These mutations lead to a deficiency or dysfunction of C1INH, resulting in the characteristic symptoms of HAE. The other options are incorrect because:

**Why Each Wrong Option is Incorrect**
**Option A:** The deficiency of C1 inhibitor (C1INH) is a hallmark of HAE, making this option incorrect. C1INH plays a crucial role in regulating the complement system and preventing excessive activation.

**Option B:** Urticaria is a common symptom of HAE, often accompanied by angioedema. This option is incorrect because urticaria is indeed associated with HAE.

**Option C:** Pruritus (itching) is usually absent in HAE, as the swelling is typically painless and non-pruritic. This option is incorrect because pruritus is not a characteristic symptom of HAE.

**Clinical Pearl / High-Yield Fact**
HAE can be caused by various mutations in the SERPING1 gene, leading to a deficiency or dysfunction of C1INH. The condition is often misdiagnosed as an allergic reaction or other conditions, highlighting the importance of accurate diagnosis and genetic testing.

**Correct Answer Line**
✓ Correct Answer: D. Autosomal recessive disorder