This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
[{'content': 'Which of the following gene defect is associated with the development of medullary carcinoma of thyroid- \nSelect and explain. \nA. RET Proto Oncogene, B. Fap gene., C. Rb gene, D. BRCA 1 gene', 'role': 'user'}, {'content': "Answer: A \nExplanation: Thyroid carcinoma\n\nThe major types of carcinoma and their relative frequency:-\n\n\xa0 Papillary carcinoma\xa0→\xa0 75% to 85% (most common)\xa0\xa0\n\xa0 Medullary carcinoma\xa0\xa0→\xa05%\n\xa0\xa0Follicular carcinoma\xa0→\xa010% to 20%\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\n\xa0 Anaplastic carcinoma\xa0→\xa0< 5%\n\nMost thyroid carcinomas are derived from the follicular epithelium , except for medullary carcinoma which is derived from the parafallicular or 'C' cells .\nGenetic factors in different thyroid carcinoma\nPapillary\xa0\xa0→\xa0 Tyrosine kinase receptors RET or NTR K1\xa0\n\n\xa0\xa0 \xa0 \xa0 \xa0 \xa0RAS mutation\n\xa0 \xa0 \xa0 \xa0 \xa0 BRAF oncogene\n\nFollicular\xa0\xa0→\xa0RAS oncogene (NRAS, HRAS and KRAS)\n\n\xa0\xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0\xa0PAX8- PPARr 1 translocation\n\nMedullary\xa0→\xa0RET proto oncogene.\nFamilial medullary cancers account for most inherited cases of thyroid cancer.\nFamilial nonmedullary thyroid cancers (papillary and follicular) are very rare.", 'role': 'assistant'}]