RET and medullary thyroid gland carcinoma: However, the second event (e.g., loss of the normal allele or duplication of the RET-mutant allele [24]) may require only a minor genetic alteration, particularly in association with an M918T mutation, as overall mutational burden in MTC is exceedingly low [15], and oncogenic progression of C cells from normal, to hyperplastic, to malignant evolves rapidly, and may occur in the first months of life [25].