Wiskott Aldrich syndrome true is –
**Core Concept**
Wiskott-Aldrich syndrome (WAS) is a rare X-linked recessive disorder characterized by eczema, thrombocytopenia, and recurrent infections. It is caused by mutations in the WAS gene, which encodes a protein crucial for platelet function and signaling.
**Why the Correct Answer is Right**
The correct answer is related to the pathophysiology of WAS, which involves impaired platelet signaling and function. The WAS protein, also known as WASP (Wiskott-Aldrich syndrome protein), plays a critical role in the regulation of the actin cytoskeleton in platelets. This leads to abnormalities in platelet morphology and function, resulting in thrombocytopenia and bleeding tendencies. Additionally, impaired T-cell function and increased susceptibility to infections are also characteristic of WAS.
**Why Each Wrong Option is Incorrect**
* **Option A:** WAS is not primarily caused by a defect in the coagulation cascade, but rather by impaired platelet function and signaling.
* **Option B:** While eczema is a common feature of WAS, it is not the primary diagnostic criterion.
* **Option C:** WAS is not typically associated with primary immunodeficiency, but rather with impaired platelet function and increased susceptibility to infections.
**Clinical Pearl / High-Yield Fact**
Wiskott-Aldrich syndrome is a classic example of a disease caused by a defect in platelet signaling, highlighting the importance of the actin cytoskeleton in platelet function.
**Correct Answer: B. Eczema is a common feature of Wiskott-Aldrich syndrome.**