The identification of mutations in the Aryl hydrocarbon receptor interacting 
protein (AIP) gene in a subset of familial isolated pituitary adenoma (FIPA) 
cases has recently expanded our understanding of the pathophysiology of 
inherited pituitary adenoma disorders. However, a genetic cause of has not yet 
been determined in the majority (85%) of FIPA families and half of the families 
with isolated familial somatotropinoma. Several studies and reviews have 
assessed the genetic and clinical features of AIP-mutated FIPA patients, which 
range from a complete lack of symptoms in adult/elderly individuals to large, 
aggressive early-onset pituitary tumors. In this study, we aimed to briefly 
revise the data available for the 11q13 locus and other additional loci that 
have been implicated in genetic susceptibility to FIPA: 2p16-12; 3q28; 
4q32.3-4q33; chr 5, 8q12.1, chr 14, 19q13.4 and 21q22.1. These candidate regions 
may contain unidentified gene(s) that can be potentially disrupted in 
AIP-negative FIPA families. A better knowledge of these susceptibility loci may 
disclose modifier genes that are likely to play exacerbating or protective roles 
in the phenotypic diversity of AIP-mutated families.