Familial isolated pituitary adenoma is independent of genotype in a novel mouse model of disease.

Human familial isolated pituitary adenoma (FIPA) has been linked to germline heterozygous mutations in the gene encoding the aryl hydrocarbon receptor-interacting protein (AIP, also known as ARA9, XAP2, FKBP16, or FKBP37). To investigate the hypothesis that AIP is a pituitary adenoma tumor suppressor via its role in aryl hydrocarbon receptor (AHR) signaling, we have compared the pituitary phenotype of our global null () mouse model with that of a conditional null model () carrying the same deletion, as well as pituitary phenotypes of global null and conditional null animals. We demonstrate that germline heterozygosity results in a high incidence of pituitary tumors in both sexes, primarily somatotropinomas, at 16 months of age.