Medullary carcinoma of thyroid is associated with which of the following gene defect?: (A) Ret Proto Oncogene, (B) FAP gene, (C) Rb gene, (D) BRCA 1 gene
Answer is A. Point mutation in RET proto-oncogene play an impoant role in the development of both familial & sporadic medullary carcinomas. Medullary carcinoma is a neuroendocrine neoplasm of thyroid derived from the parafollicular cells or C-cells of thyroid. It secretes calcitonin. Tumor arise sporadically in 80% cases, remainder is associated with MEN Type IIA Or IIB syndrome. Most common presentation is mass in the neck. Ref: Genetics in Clinical Practice: New Directions for Nursing and Health Care By Dale Halsey Lea, Page 158 ; Robbins Pathologic Basis of Disease 6th Edition, Page 289, 292, 1145-6