RET and medullary thyroid gland carcinoma: Based on the specific RET mutation (genotype) associated with phenotypes, the Revised American Thyroid Association (ATA) Guidelines (hereafter referred to as ATA-2015), among others, have defined the management of MTC risk category (moderate risk, ATA-MOD; high risk, ATA-H; and highest risk, ATA-HST) of each specific RET mutation and recommended the optimal age of prophylactic total thyroidectomy, timing by which patients carrying germline RET mutations should be screened for PHEO and HPTH, penetrance estimations, and surgical windows of opportunity [1, 18, 19].