All are features of Wiskott Aldrich syndrome, EXCEPT:
**Core Concept**
Wiskott-Aldrich Syndrome (WAS) is a rare X-linked recessive disorder characterized by eczema, thrombocytopenia, immune deficiency, and bloody diarrhea. It results from mutations in the WAS gene, which encodes the WAS protein (WASp) crucial for platelet function, immune cell signaling, and cytoskeletal organization.
**Why the Correct Answer is Right**
Wiskott-Aldrich Syndrome is characterized by a triad of symptoms:
- Eczema: due to impaired T-cell function and decreased production of Th1 cytokines.
- Thrombocytopenia: caused by a deficiency in WASp, leading to abnormal platelet morphology and function.
- Eosinophilia: often observed due to increased sensitivity to IgE and enhanced eosinophil activation.
- Immune deficiency: results in recurrent infections, particularly with encapsulated bacteria.
- Bloody diarrhea: can occur due to platelet dysfunction and gastrointestinal bleeding.
**Why Each Wrong Option is Incorrect**
**Option A:** Not a feature of Wiskott-Aldrich Syndrome.
**Option B:** Not a feature of Wiskott-Aldrich Syndrome.
**Option C:** Not a feature of Wiskott-Aldrich Syndrome.
**Clinical Pearl / High-Yield Fact**
Wiskott-Aldrich Syndrome is a classic example of a disorder with a complex interplay between immune cell signaling, cytoskeletal organization, and platelet function. Remember the triad of symptoms (eczema, thrombocytopenia, and immune deficiency) and the importance of WASp in maintaining normal platelet morphology and immune cell function.
**Correct Answer:** D.