Mutations in the aryl hydrocarbon receptor interaction protein gene (AIP) occur in familial pituitary adenomas as an autosomal dominant inheritance with a 15-30% penetrance. The AIP mutation-associated pituitary adenomas are generally large, the onset of disease is early and treatment failure frequent. Genetic screening is also offered in Denmark and enables the detection of mutation carriers, and thus early diagnosis and treatment. Mutations have been recorded among Danish patients and their families.