RET mutation in MEN2A cases is of three levels: Level 3 is most aggressive cases and metastasizes in the 1st year of life with mutations in RET codon 611, 618, 620, and 622; Level 2 is of a high risk of MTC with RET mutations in codons 609, 768,790, 804, and 891; and thyroidectomy is recommended for levels 3 and 2 patients before age 5, and level 1 is still a risk of developing MTC in RET mutations affecting the codons 609, 768, 790, 804, and 891 [20-22]. The gene discussed is RET; the disease is medullary thyroid gland carcinoma.