Results . Functional classification of AIP mutations into two groups: protein present or absent . AIP is coded by a gene on 11q13 spanning six exons (Fig. 1A ). Various genetic alterations have been found in patients with pituitary adenomas, such as whole gene or exon deletions, promoter mutations, insertions/deletions, splicing mutations as well as nonsense and missense mutations. While loss-of-function truncating mutations are listed as pathogenic in databases, many missense variants ...