The Endocrine System
Which of the following gene defect is associated with development of medullary carcinoma of thyroid? (LQ)
|A||RET proto oncogene|
|D||BRCA 1 gene|
a. The major types of carcinoma and their relative frequency ;-
b. Papillary cacinoma→75% to 85% (most common) → Medullary carcinoma →5%
Most thyroid carcinomas are derived from the follicular epithelium, except for medullary carcinoma which is derived from the Follicular carcinoma → 10% to 2% Anaplastic carcinoma →<5%
c. parafallicular or 'C' cells.
d. Genetic factors in different thyroid carcinoma
i. Papillary → o Tyrosine kinase receptors RET or NTRK 1
o RAS mutation
o BRAF oncogene
ii. Follicular → o RAS oncogene (NRAS, HRAS and KRAS)
o PAX8- PPARr1 translocation
iii. Medullary → o RET protooncogene.
iv. Familial medullary cancers account for most inherited cases of thyroid cancer.
v. Familial nonmedullary thyroid cancers (papillary and follicular) are very rare.