Several studies have implicated germline variants and susceptibility loci in genes involved in DNA damage response and other pathways (for example, CHEK2, ATM, BRCA2, and additional candidate predisposition genes identified by next-generation sequencing), although no single high-penetrance gene has been established as the predominant driver of familial non-medullary thyroid cancer [39,40,41,42]. Here, CHEK2 is linked to medullary thyroid gland carcinoma.