RET and medullary thyroid gland carcinoma: p.Val804Met is the most common pathogenic RET variant seen in large population databases such as gnomAD (39), and is likely to be sub penetrant, such that this variant is over-represented in MEN2 in patients without a family history, whereas when MEN2 is associated with a clear family history of MTC then p.Cys634Arg is the most common variant detected (7).