Interestingly, one patient harboring RET-C634R pathogenic variant had, not only medullary thyroid carcinoma and pheochromocytoma, but also primary hyperparathyroidism, as seen in a single case according to our series (being the rarest component among the endocrine tumour tumor in the syndrome) [32]. This evidence concerns the gene RET and hereditary pheochromocytoma-paraganglioma.