**Core Concept**
Pemphigus vulgaris is an autoimmune disease characterized by the formation of intraepithelial blisters due to the loss of intercellular connections between keratinocytes. It is caused by autoantibodies against desmoglein 3 proteins, which are crucial for cell-to-cell adhesion in the epidermis.

**Why the Correct Answer is Right**
In pemphigus vulgaris, autoantibodies bind to desmoglein 3 proteins, disrupting the normal adhesion between keratinocytes. This leads to the formation of intraepithelial blisters and ultimately, skin lesions. The presence of these autoantibodies is a hallmark of the disease and is used as a diagnostic criterion.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because pemphigus vulgaris is not primarily caused by a genetic mutation.
**Option B:** This option is incorrect because pemphigus vulgaris is not an infection, but rather an autoimmune disease.
**Option C:** This option is incorrect because pemphigus vulgaris is not characterized by the presence of eosinophils, but rather by the presence of autoantibodies against desmoglein 3 proteins.

**Clinical Pearl / High-Yield Fact**
The Nikolsky's sign, which is a positive result when gentle pressure on the skin causes the epidermis to separate from the dermis, is a classic clinical finding in pemphigus vulgaris.

**Correct Answer: D. All of the above.**