To date, the number of molecular genetic factors unequivocally linked to pituitary tumours can be counted on the fingers of one hand: (1) GNAS1 activation in acromegaly; (2) the MENIN and p27Kip1 (CDKN1B) mutations associated with multiple endocrine neoplasia type 1; (3) mutations of PRKA1RA with loss of 17q22-24 in Carney complex, and (4) aryl hydrocarbon receptor interacting protein gene mutations in 15% of familial isolated pituitary adenomas and 50% of familial isolated acromegaly