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Multiple endocrine neoplasia type 2B--genetic basis and clinical expression
1Department of Surgery, University of California, 94143, San Francisco, CA, USA.
Surgical Oncology
|May 18, 2001
Summary
Multiple endocrine neoplasia type 2B (MEN 2B) is an inherited disorder caused by a RET proto-oncogene mutation. Early genetic screening and thyroidectomy are crucial for managing aggressive medullary thyroid carcinoma and pheochromocytoma.
Area of Science:
- Endocrinology
- Genetics
- Oncology
Background:
- Multiple endocrine neoplasia type 2B (MEN 2B) is a rare, autosomal dominant inherited endocrine disorder.
- Characterized by medullary thyroid carcinoma (MTC), pheochromocytoma, mucosal neuromas, and marfanoid habitus.
- Caused by a specific mutation (Met918Thr) in the RET proto-oncogene.
Purpose of the Study:
- To summarize the key features and management strategies for MEN 2B.
- To highlight the aggressive nature of MTC in MEN 2B compared to MEN 2A.
- To emphasize the importance of early genetic screening and prophylactic interventions.
Main Methods:
- Review of clinical characteristics and genetic basis of MEN 2B.
- Analysis of disease presentation, progression, and treatment outcomes.
- Discussion of diagnostic criteria and management guidelines.
Main Results:
- MEN 2B-associated MTC is aggressive, presenting early (age 3) with multicentricity, bilaterality, and early metastases.
- Pheochromocytomas are common, usually bilateral, and rarely malignant; adrenalectomy should precede thyroidectomy.
- RET proto-oncogene mutation at codon 918 is the causative genetic defect.
Conclusions:
- Genetic screening for RET mutations in at-risk infants is essential.
- Prophylactic total thyroidectomy is recommended for all individuals with RET mutations, even before symptom onset.
- Timely surgical intervention for pheochromocytoma and thyroid cancer is critical for patient survival.