RET and familial isolated hyperparathyroidism: It may be sporadic or occur in the context of a genetic endocrine syndrome as in hyperparathyroidism/jaw tumour syndrome (HPT-JT), Multiple Endocrine Neoplasia type 1 (MEN1), type 2A (MEN2A), and familial isolated hyperparathyroidism (FIHP) [14–16].