**Core Concept**
Ichthyosis vulgaris is a common inherited disorder characterized by dry, scaly skin due to mutations in the filaggrin gene. Filaggrin is a key protein involved in the structure and function of the skin's natural moisturizing barrier.

**Why the Correct Answer is Right**
The filaggrin gene (FLG) mutations lead to a deficiency in filaggrin protein, resulting in impaired skin hydration and increased permeability. This disrupts the skin's natural barrier function, causing dryness and scaling. The inheritance pattern of ichthyosis vulgaris is autosomal dominant, meaning a single copy of the mutated gene is sufficient to cause the condition.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as ichthyosis vulgaris is not caused by mutations in the filaggrin gene. Other genetic disorders, such as lamellar ichthyosis, may be caused by different genetic mutations.
**Option B:** This option is incorrect as autosomal recessive inheritance would require two copies of the mutated gene (one from each parent) to cause the condition.
**Option C:** This option is incorrect as ichthyosis vulgaris is not a sex-linked disorder, and the inheritance pattern is not X-linked dominant.

**Clinical Pearl / High-Yield Fact**
Ichthyosis vulgaris is often associated with other skin conditions, such as atopic dermatitis, and may also be linked to allergies and asthma. Patients with ichthyosis vulgaris may benefit from topical moisturizers and barrier repair creams to manage symptoms.

**Correct Answer: A. Autosomal dominant inheritance.**