Although age-dependent MTC penetrance predetermined by specific RET mutations are different in each group, the lag time between developing MTC and progression to lymph node metastases is similar (Voss et al. 2017, Machens et al. 2021b) and MTC-specific survival rates and outcomes are not different in both groups (Raue et al. 2019). This evidence concerns the gene RET and medullary thyroid gland carcinoma.