Immunohistochemical examination of the MTC in 24 patients revealed 66.7% CT, 80% synaptophysin (Syn) in 25 patients, 87.5% chromogranin A (CgA) in 24 patients, 100% Thyroid transcription factor 1 (TTF-1) in 25 patients, 81.8% Congo red staining in 21 patients and 44% thyroglobulin (Tgin) 25 patients (Table 2). This evidence concerns the gene TTF1 and medullary thyroid gland carcinoma.