Wiskott Aldrich not true is -a) Raised IgEb) Raised IgMc) Reduced IgAd) CD4 and CD8 defect

**Core Concept**
Wiskott-Aldrich syndrome (WAS) is a rare X-linked recessive disorder characterized by eczema, thrombocytopenia, immune deficiency, and bloody diarrhea. It is caused by mutations in the WAS gene, which encodes the WAS protein (WASp).

**Why the Correct Answer is Right**
The correct answer is related to the immunological features of WAS. The disease is primarily associated with a deficiency in IgM antibodies, which is a key component of the humoral immune response. This is because the WAS protein plays a crucial role in the activation and signaling of B cells, leading to impaired antibody production. In contrast, IgE and IgM levels are often elevated in WAS patients, while IgA levels are typically reduced.

**Why Each Wrong Option is Incorrect**
* **Option A:** Raised IgE is actually a feature of WAS, as patients often exhibit elevated levels of IgE antibodies, contributing to their eczematous skin lesions.
* **Option B:** Raised IgM is also associated with WAS, as these patients often have impaired antibody production, leading to elevated levels of IgM.
* **Option C:** Reduced IgA is indeed a characteristic of WAS, as the disease impairs the activation and signaling of B cells, leading to impaired antibody production, including IgA.
* **Option D:** CD4 and CD8 defects are not primary features of WAS. While WAS patients may exhibit some T-cell dysfunction, the disease is primarily characterized by B-cell dysfunction and impaired antibody production.

**Clinical Pearl / High-Yield Fact**
Wiskott-Aldrich syndrome is a classic example of a disorder associated with impaired B-cell function, leading to reduced antibody production and increased susceptibility to infections. This highlights the importance of understanding the role of WASp in B-cell signaling and activation.

**Correct Answer: C. Reduced IgA is indeed a characteristic of Wiskott-Aldrich syndrome.