**Core Concept**
McCune-Albright syndrome is a rare genetic disorder characterized by the triad of polyostotic fibrous dysplasia, café-au-lait skin spots, and endocrine disorders. This condition results from a mutation in the GNAS gene, which encodes the Gs alpha subunit of G-protein coupled receptors.

**Why the Correct Answer is Right**
The GNAS mutation leads to constitutive activation of G-protein coupled receptors, resulting in excessive cyclic AMP (cAMP) production. This increase in cAMP levels triggers various downstream signaling pathways, including those involved in bone and skin development. The resulting polyostotic fibrous dysplasia and café-au-lait skin spots are due to abnormal osteoblast and melanocyte differentiation, respectively. Additionally, the constitutive activation of G-protein coupled receptors in endocrine tissues leads to an overproduction of hormones, resulting in various endocrine disorders.

**Why Each Wrong Option is Incorrect**

**Option A:** Polyarteritis nodosa is a different condition characterized by inflammation of blood vessels, not a feature of McCune-Albright syndrome.

**Option B:** Turner syndrome is a genetic disorder affecting females, characterized by short stature, ovarian dysgenesis, and other features, not associated with McCune-Albright syndrome.

**Option C:** Ehlers-Danlos syndrome is a group of genetic disorders affecting collagen production, leading to skin hyperextensibility and joint hypermobility, not a feature of McCune-Albright syndrome.

**Clinical Pearl / High-Yield Fact**
McCune-Albright syndrome is often associated with an increased risk of osteosarcoma, a type of bone cancer, particularly in patients with polyostotic fibrous dysplasia. It is essential to monitor patients with this condition for early signs of osteosarcoma.

**Correct Answer:** D.