MTC diagnosis relies on elevated serum calcitonin and CEA, fine-needle aspiration with calcitonin washout, and confirmation by histopathology (amyloid deposition, Congo-red positivity) with immunostaining for calcitonin [2,7,8], even though calcitonin-negative cases are present [9]. The gene discussed is CALCA; the disease is medullary thyroid gland carcinoma.