<prompt> The expression of the following oncogene is associated with a high incidence of Medullary carcinoma of thyroid -P53Her2neuRET proto-oncogeneRb gene  <response>: RET protooncogene is a growth factor receptor receptor tyrosine kinase The RET protein is a receptor for the glial cell lined derived neurotrophic factor and structurally related proteins that promote cell survival during neural development.RET is normally expressed in the following cellsParafollicular C cells of the thyroidAdrenal medullaParathyroid cell precursors. Point mutation in the RET protooncogenes are associated with the following disorders. i MEN type 2A -There is point mutation in RET extracellular domain which causes constitutive dimerization and activation leading to:-Medullary thyroid carcinomaAdrenal and parathyroid tumoursii MEN type 2B -Point mutation in the RET cytoplasmic catalytic domain alter the substrate specificity of the tyrosine kinase and leads to:-Thyroid tumoursAdrenal tumorsiii Sporadic Medullary thyroid carcinoma Somatic rearrangement of the RET geneiv Hirschsprung diseaseThis is caused by complete loss of RET function. 