Which of the following gene defect is associated with the development of medullary carcinoma of thyroid-

Thyroid carcinoma The major types of carcinoma and their relative frequency:-   Papillary carcinoma →  75% to 85% (most common)     Medullary carcinoma  → 5%   Follicular carcinoma → 10% to 20%               Anaplastic carcinoma → < 5% Most thyroid carcinomas are derived from the follicular epithelium , except for medullary carcinoma which is derived from the parafallicular or 'C' cells . Genetic factors in different thyroid carcinoma Papillary  →  Tyrosine kinase receptors RET or NTR K1            RAS mutation           BRAF oncogene Follicular  → RAS oncogene (NRAS, HRAS and KRAS)                    PAX8- PPARr 1 translocation Medullary → RET proto oncogene. Familial medullary cancers account for most inherited cases of thyroid cancer. Familial nonmedullary thyroid cancers (papillary and follicular) are very rare.