**Core Concept**
Familial benign pemphigus is a rare, autosomal dominant genetic disorder characterized by the development of intraepithelial blisters on the skin due to mutations affecting the desmoplakin protein, a key component of desmosomes.

**Why the Correct Answer is Right**
Familial benign pemphigus is caused by mutations in the DSP gene, which encodes the desmoplakin protein. This leads to impaired cell-cell adhesion, causing the formation of intraepithelial blisters. The disorder typically presents in childhood with skin lesions and may also involve the mucous membranes.

**Why Each Wrong Option is Incorrect**
**Option A:** This is incorrect because Hailey-Hailey disease is another autosomal dominant disorder affecting the desmoglein 1 protein, leading to a different type of skin blistering.
**Option B:** This is incorrect because Pemphigus vulgaris is an autoimmune disorder affecting the desmoglein 3 protein, causing more severe skin blistering.
**Option C:** This is incorrect because Epidermolysis bullosa simplex is caused by mutations in the KRT5 or KRT14 genes encoding keratin proteins, leading to skin fragility and blistering.

**Clinical Pearl / High-Yield Fact**
Familial benign pemphigus is often mistaken for other blistering disorders, but its characteristic presentation in childhood and autosomal dominant inheritance pattern can help in making a diagnosis.

**Correct Answer: C.