**Core Concept**
Pseudohypoparathyroidism (PHP) is a rare genetic disorder characterized by resistance to parathyroid hormone (PTH), leading to hypocalcemia and hyperphosphatemia. It is primarily caused by mutations in the GNAS gene, which encodes the Gαs subunit of G-proteins involved in PTH signaling.

**Why the Correct Answer is Right**
Pseudohypoparathyroidism is a complex disorder involving impaired G-protein coupled signaling in osteoblasts, kidney cells, and other tissues. The GNAS gene mutations lead to decreased activity of the Gαs subunit, resulting in reduced PTH receptor signaling and subsequent resistance to PTH. This manifests as hypocalcemia, hyperphosphatemia, and elevated PTH levels.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is a common feature of pseudohypoparathyroidism, characterized by short stature, round face, and short fourth metacarpals due to impaired bone mineralization and growth.

**Option B:** This option is incorrect as pseudohypoparathyroidism is primarily caused by GNAS gene mutations, not fibroblast growth factor receptor 3 (FGFR3) mutations, which are associated with achondroplasia.

**Option C:** This option is incorrect as pseudohypoparathyroidism does not typically present with hypercalcemia, but rather hypocalcemia and hyperphosphatemia due to PTH resistance.

**Clinical Pearl / High-Yield Fact**
Pseudohypoparathyroidism is a rare disorder, but its diagnosis is essential for distinguishing it from other causes of hypocalcemia, such as vitamin D deficiency or hypomagnesemia. A high index of suspicion and genetic testing are crucial for accurate diagnosis.

**Correct Answer: C. This option is incorrect as pseudohypoparathyroidism does not typically present with hypercalcemia, but rather hypocalcemia and hyperphosphatemia due to PTH resistance.**