The identification of the main genetic driver of the hyperparathyroidism with Jaw Tumours (HPT-JT, MIM #145001) syndrome first [8] and then of familial and sporadic PC later [9], the CDC73 gene, helped in the molecular diagnosis and also in the follow up of subjects at risk to develop an aggressive parathyroid lesion, in case of familial forms. Here, CDC73 is linked to hyperparathyroidism.