**Question:** Vitiligo all are true except

A. Vitiligo is a chronic acquired immune disorder affecting melanocytes.
B. Vitiligo is a genetic disorder primarily caused by mutations in the melanocortin 1 receptor (MC1R) gene.
C. Vitiligo is primarily caused by an autoimmune response against melanocytes.
D. Vitiligo is primarily caused by a deficiency of melanocytes in the skin and mucous membranes.

**Correct Answer:** D. Vitiligo is primarily caused by a deficiency of melanocytes in the skin and mucous membranes.

**Core Concept:** Vitiligo is a chronic autoimmune disorder characterized by the destruction of melanocytes, which are pigment-producing cells responsible for skin and hair color. It results in the development of hypopigmented macules or patches on the skin and mucous membranes.

**Why the Correct Answer is Right:** Vitiligo is primarily caused by an autoimmune response against melanocytes, leading to their destruction and depletion. This is supported by the presence of melanocyte-specific antibodies and T cells in the affected skin. The correct answer, option D, highlights the deficiency of melanocytes as the primary cause of vitiligo.

**Why Each Wrong Option is Incorrect:**

A. Vitiligo is not primarily caused by a deficiency of melanocytes, but rather by an autoimmune response against melanocytes.
B. Mutations in the melanocortin 1 receptor (MC1R) gene are associated with vitiligo susceptibility but are not the primary cause of the disease.
C. Although an autoimmune response against melanocytes contributes to vitiligo development, it is not the only cause. The primary cause is believed to be an autoimmune response against melanocytes leading to their destruction and depletion.

**Clinical Pearl:**

Vitiligo can be challenging to diagnose due to the multifactorial nature of the disease. A detailed history and physical examination are essential in establishing a diagnosis. Treatment options include topical steroids, immunosuppressive agents, and phototherapy, among others, to manage the autoimmune response and repigment the skin. In some cases, genetic counseling may be necessary for affected individuals and their families.