Medullary carcinoma of thyroid is associated with mutation in
**Core Concept**
Medullary carcinoma of the thyroid (MTC) is a rare type of thyroid cancer that originates from the parafollicular cells, also known as C-cells. The pathogenesis of MTC involves a genetic mutation that leads to the uncontrolled proliferation of these cells.
**Why the Correct Answer is Right**
MTC is primarily associated with mutations in the RET proto-oncogene, which encodes a receptor tyrosine kinase involved in cell signaling pathways. The most common mutations in MTC are germline mutations in the RET gene, which are inherited in an autosomal dominant pattern. These mutations lead to the constitutive activation of the RET receptor, resulting in the uncontrolled growth and survival of C-cells. In addition to germline mutations, somatic mutations in the RET gene can also occur in sporadic MTC cases.
**Why Each Wrong Option is Incorrect**
**Option A:** Mutations in the BRAF gene are associated with papillary thyroid carcinoma, not medullary carcinoma.
**Option B:** Mutations in the RAS gene are associated with various types of cancer, including pancreatic cancer, but not specifically with MTC.
**Option C:** Mutations in the TP53 gene are associated with Li-Fraumeni syndrome, an inherited cancer syndrome that predisposes individuals to a variety of cancers, but not specifically with MTC.
**Clinical Pearl / High-Yield Fact**
MTC is often associated with other endocrine neoplasms, such as pheochromocytoma, and can be part of multiple endocrine neoplasia (MEN) syndromes, including MEN 2A and MEN 2B.
**Correct Answer:** C.