Familial Isolated Pituitary Adenoma Patients Research Articles

SAT-462 AIP Mutation-Positive Patients with Somatotropinomas End up Taller and Requiring Radiotherapy More Often Compared to AIP Mutation-Negative Patients: Data from 784 Familial and Young-Onset Cases

Introduction: Germline mutations in the aryl hydrocarbon receptor-interacting protein gene (AIP) are responsible for up to 50% of familial isolated pituitary adenoma (FIPA) kindreds affected only with somatotropinomas. AIP mutation-positive (AIPmut) somatotropinomas present earlier, more aggressively and are often more resistant to therapy. We aimed to further characterise AIPmut somatotropinomas in terms of clinical features and outcomes. Methods: We studied AIPmut somatotropinomas which presented clinically; prospectively-diagnosed AIPmut somatotropinomas (i.e. somatotropinomas diagnosed following genetic and clinical screening) were excluded from the analysis. Indications for AIP genetic testing were: i) FIPA patients, ii) sporadic pituitary GH-secreting macroadenomas with disease onset <30y, or iii) GH-secreting microadenomas with age of onset <18y. Results: Out of 784 patients with somatotropinomas included in our study, 139 had an AIP mutation (17.7%). In comparison to AIP mutation-negative somatotropinomas (AIPneg), patients with AIPmut somatotropinomas had a younger age at first symptoms (18.9±9.0 vs 26.1±11.7y; p<0.001) and at diagnosis (24.1±10.5 vs 30.1±12.4y; p<0.001), higher rates of pituitary apoplexy (9.5 vs 1.9%; p<0.001), suprasellar extension (66.1 vs 45.3%; p=0.003), extrasellar extension (81.2 vs 68.3%; p=0.032) and a higher mean number of pituitary deficiencies at diagnosis (0.4±0.9 vs 0.2±0.6, p=0.020). The clinical diagnosis of most AIPmut patients was gigantism (55.4 vs 18.4%, p<0.001). The mean final height was higher in the AIPmut somatotropinoma subgroup (187.2±18.4 vs 177.2±19.6cm; p<0.001). AIPmut male patients ended up taller than AIPneg males (193.0±17.7 vs 183.0±23.1cm; p=0.002); similarly, AIPmut female patients were taller than AIPneg ones (175.5±13.0 vs 169.2±8.6cm; p=0.007). Both AIPmut and AIPneg groups had more male patients (60.4% in AIPmut and 52.7% in AIPneg groups). The mean number of overall treatments (2.34±1.65 vs 2.32±1.45; p=0.896) or surgical operations (1.05±0.78 vs 1.07±0.63; p=0.745) did not differ significantly between AIPmut and AIPneg somatotropinomas; however, AIPmut patients were more often treated with radiotherapy (41.7 vs 28.0%; p=0.020). Conclusions:AIPmut somatotropinomas present earlier and more often with pituitary apoplexy, suprasellar and extrasellar extensions, and had a higher number of pituitary deficiencies. The remarkably higher final height in the AIPmut setting, both in males and females, likely reflects the earlier onset of disease, but also emphasizes the management challenges as suggested by the increased proportion of patients requiring radiotherapy.

Three Novel MEN1 Variants in AIP-Negative Familial Isolated Pituitary Adenoma Patients

Objectives: Pituitary adenomas (PAs) may rarely occur in well-defined hereditary conditions, like multiple endocrine neoplasia type 1 (MEN1) syndrome and familial isolated pituitary adenoma (FIPA) associated with germline mutations in MEN1 and AIP, respectively. This study aimed to assess MEN1 genetic abnormalities in AIP mutation-negative FIPA patients, not associated with MEN1 components. Methods: Among 20 patients evaluated in 13 FIPA families, 12 were previously reported as AIP mutation-negative. In this study, 6 new families with 8 patients were recruited. All patients were subjected to multiplex ligation-dependent probe amplification to detect copy number variations in AIP and MEN1, and AIP sequencing was performed in additional patients. AIP mutation-negative patients were subjected to MEN1 sequencing. Results: Our cohort revealed only 3 novel heterozygous MEN1 variants including c.1846T>A p.(*616Argext*21), rs778272737:T>C, and rs972128957:C>T in 2 families, with patients diagnosed with Cushing disease, nonfunction al adenoma, and acromegaly, respectively. Among them, c.1846T>A p. (*616Argext*21) is a stop codon read-through, whereas the others are 3′UTR variations. MEN1 variation frequency was detected as 15%. Conclusions: MEN1 alterations can be of significance in FIPA patients and screening could be offered to AIP mutation-negative patients without MEN1 features. Further studies are needed to clarify the role of MEN1 in FIPA patients.

A novel truncating AIP mutation, p.W279*, in a familial isolated pituitary adenoma (FIPA) kindred

Familial isolated pituitary adenomas (FIPA) constitute 2-3% of pituitary tumours. AIP is the most commonly mutated gene in FIPA. We herein report a novel germline mutation of the AIP gene in a family with FIPA. We present two patients, a father and his 12-year-old daughter, diagnosed clinically and using laboratory measures with acromegaly-gigantism. Both underwent transsphenoidal hypophyseal surgery for macroadenomas. We initially detected a novel heterozygous germline AIP mutation, c.836G>A (p.W279*), in the father's DNA. We then found the same mutation in his affected daughter. Pituitary adenomas associated with AIP mutations mostly present as FIPA (68%) at an early age (78% occur at <30 years old). They are often growth hormone (GH) - or prolactin - secreting macroadenomas (88%) that have already extended beyond the sella at the time of diagnosis. Acromegalic cases are resistant to somatostatin analogues and multimodal management is frequently essential to control the disease. Our patients had normalized GH/IGF-1 values soon after surgery, although enough time may not have elapsed to reach final cure. While penetrance of the disease can be as low as 10% in FIPA, especially children and young patients with somatotropinoma and prolactinoma should be surveyed for inactivating mutations or deletions in AIP. Determining the causative mutations may be of assistance in early diagnosis, treatment success, and genetic counseling.

Do the aryl hydrocarbon receptor interacting protein variants (Q228K and Q307R) play a role in patients with familial and sporadic hormone-secreting pituitary adenomas?

The aim of this study was to examine mutations in the aryl hydrocarbon receptor-interacting protein (AIP) gene by sequence analysis of exons 1-6 using leukocyte genomic DNA obtained from a cohort of familial isolated pituitary adenoma (FIPA) and apparent sporadic functional pituitary adenoma Turkish patients. Fourteen FIPA and 90 sporadic pituitary adenoma (somatotrophinoma, prolactinoma, and corticotrophinoma) patients, 1 sporadic gigantism case, and 70 healthy controls were included in the study. We did not detect AIP mutations in patients with FIPAs or sporadic pituitary adenomas, including the gigantism case. Only two exonic homozygous missense single-nucleotide polymorphisms (rs641081 [Q228K] and rs4930195 [Q307R]) were identified in the AIP locus. Minor allele frequencies of the Q307R and Q228K variants were significantly higher in FIPA patients compared to controls. In addition, the minor allele frequency of the Q228K variant was significantly increased in patients with sporadic somatotrophinomas compared to controls, whereas the minor allele frequency of the Q307R variant was significantly increased in corticotrophinoma patients compared to controls. Conversely, the minor allele frequencies of Q228R and Q307R variants were similar between patients with prolactinomas and controls. No AIP gene mutation or variant was observed in the sporadic gigantism patient. These results suggest that Q228K and Q307R variants in the AIP gene might be involved in the genetic susceptibility to familial and sporadic pituitary adenomas (somatotrophinoma and corticotrophinoma) in the Turkish population.

Familial isolated pituitary adenomas: An emerging clinical entity

Familial pituitary tumors are increasingly recognized. While some of these cases are related to wellknown syndromic conditions such as multiple endocrine neoplasia type 1 (MEN1) or Carney complex, others belong to the familial isolated pituitary adenoma (FIPA) patient group. The discovery of heterozygous, loss-of-function germline mutations in the gene encoding the aryl hydrocarbon receptor interacting protein (AIP) in 2006 has subsequently enabled the identification of a mutation in this gene in 20% of FIPA families and 20% of childhood-onset simplex soma- totroph adenomas. The exact mechanism by which the lack of AIP leads to pituitary adenomas is not clear. AIP mutations cause a low penetrance autosomal dominant disease with often a distinct phenotype characterized by young-onset, aggressive, large GH, mixed GH and PRL or PRL-secreting adenomas. This review aims to summarize currently available clinical data on AIP mutation-positive and negative FIPA patients.

Should aip gene screening be recommended in family members of FIPA patients with R16H variant?

Germline mutations of aryl-hydrocarbon-receptor interacting protein (AIP) are associated with pituitary adenoma predisposition. They occur in 20% of familial isolated pituitary adenoma (FIPA) and in about 3-5% of sporadic pituitary adenomas, especially in early onset somatotropinomas and prolactinomas. Our aim was to evaluate the clinical and genetic features of a large Italian FIPA family, where an AIP variant was identified. AIP direct sequencing from genomic DNA was carried out in 16 available family members. AIP R16H carriers also underwent magnetic resonance imaging and hormonal assessments. AIP mutations were also searched in 16 patients with sporadic growth hormone-secreting pituitary adenoma and in 6 unrelated patients in whom pituitary adenoma was excluded. We found an AIP R16H variation in two family members harbouring a pituitary adenoma and in 6 unaffected family members. No AIP mutation was found neither in growth hormone-secreting pituitary adenoma patients, nor in the unrelated patients without pituitary adenoma. We report a FIPA family harbouring an AIP R16H change, supporting the hypothesis that the latter represents a variant of unknown significance.

Familial pituitary adenomas – who should be tested for AIP mutations?

Familial Isolated Pituitary Adenomas (FIPA), an autosomal dominant disease with low penetrance is being increasingly recognized. FIPA families can be divided into two distinct groups based on genetic and phenotypic features. Patients with mutations in the aryl hydrocarbon receptor-interacting protein (AIP) gene are characterized by young-onset somatotroph or lactotroph macroadenomas, while in the other, larger group of FIPA patients with typically adult-onset disease and more varied adenoma types, no causative gene(s) has been identified. Young-onset macroadenoma patients can also be identified with germline AIP mutation without an apparent family history. Further data and longer follow-up are necessary to establish formal guidelines, but the current data suggest genetic screening of the AIP gene in patients with a pituitary adenoma and no other associated features who have (i) a family history of pituitary adenoma, (ii) childhood-onset pituitary adenoma or (iii) a pituitary somatotroph or lactotroph macroadenoma diagnosed before the age of 30 years.

Characterization of aryl hydrocarbon receptor interacting protein (AIP) mutations in familial isolated pituitary adenoma families.

Familial isolated pituitary adenoma (FIPA) is an autosomal dominant condition with variable genetic background and incomplete penetrance. Germline mutations of the aryl hydrocarbon receptor interacting protein (AIP) gene have been reported in 15–40% of FIPA patients. Limited data are available on the functional consequences of the mutations or regarding the regulation of the AIP gene. We describe a large cohort of FIPA families and characterize missense and silent mutations using minigene constructs, luciferase and β-galactosidase assays, as well as in silico predictions. Patients with AIP mutations had a lower mean age at diagnosis (23.6±11.2 years) than AIP mutation-negative patients (40.4±14.5 years). A promoter mutation showed reduced in vitro activity corresponding to lower mRNA expression in patient samples. Stimulation of the protein kinase A-pathway positively regulates the AIP promoter. Silent mutations led to abnormal splicing resulting in truncated protein or reduced AIP expression. A two-hybrid assay of protein–protein interaction of all missense variants showed variable disruption of AIP-phosphodiesterase-4A5 binding. In summary, exonic, promoter, splice-site, and large deletion mutations in AIP are implicated in 31% of families in our FIPA cohort. Functional characterization of AIP changes is important to identify the functional impact of gene sequence variants. Hum Mutat 31:1–11, 2010. © 2010 Wiley-Liss, Inc.

The epidemiology and genetics of pituitary adenomas

According to data derived from autopsy and radiological imaging series, pituitary tumours occur very commonly in the general population; however, most of these tumours are incidental findings with no obvious clinical impact. The historical data on the prevalence of pituitary adenomas in the clinical setting are scant and point to such tumours being relatively rare. Recent studies have shown that the prevalence of clinically relevant pituitary adenomas is 3-5 times higher than previously reported, which adds impetus to research into the aetiology of these tumours. Although the majority of pituitary adenomas are sporadic, approximately 5% of all cases occur in a familial setting and over half of these are due to Multiple Endocrine Neoplasia Type 1 (MEN-1) and Carney's Complex (CNC) disorders. Since the late 1990 s, we have described non-MEN1/CNC familial pituitary tumours that include all tumour phenotypes as a condition termed Familial Isolated Pituitary Adenomas (FIPAs). The clinical characteristics of the FIPAs vary from those sporadic pituitary adenomas, as patients with FIPAs have a younger age at diagnosis and larger tumours. About 15% of the FIPA patients have mutations in the aryl hydrocarbon receptor-interacting protein gene (AIP), which indicates that the FIPA may have a diverse genetic pathophysiology.

Familial pituitary adenomas

The majority of pituitary adenomas occur sporadically, however, about 5% of all cases occur in a familial setting, of which over half are due to multiple endocrine neoplasia type 1 (MEN-1) and Carney's complex (CNC). Since the late 1990s we have described non-MEN1/CNC familial pituitary tumours that include all tumour phenotypes, a condition named familial isolated pituitary adenomas (FIPA). The clinical characteristics of FIPA vary from those of sporadic pituitary adenomas, as patients with FIPA have a younger age at diagnosis and larger tumours. About 15% of FIPA patients have mutations in the aryl hydrocarbon receptor interacting protein gene (AIP), which indicates that FIPA may have a diverse genetic pathophysiology. This review describes the clinical features of familial pituitary adenomas like MEN1, the MEN 1-like syndrome MEN-4, CNC, FIPA, the tumour pathologies found in this setting and the genetic/molecular data that have been recently reported.

Familial Isolated Pituitary Adenomas

Over the last century several families have been described with familial isolated pituitary adenomas (FIPAs). Most commonly, family members have acromegaly or prolactinoma, but other types of pituitary adenomas can also occur. Recently, mutations in theAIP(aryl hydrocarbon receptor interacting protein) gene have been found to occur in 30–50% of FIPA patients, while for the rest of the patients the gene causing the disease is currently unknown and is a topic of intense research. Tumours in patients withAIPmutations are diagnosed at significantly younger ages and tend to be larger. Often the response to medical therapy in these patients is poor. This article discusses the clinical and genetic characteristics of this relatively recently recognised disease.

Familial Isolated Pituitary Adenomas

Over the last century several families have been described with familial isolated pituitary adenomas (FIPAs). Most commonly, family members have acromegaly or prolactinoma, but other types of pituitary adenomas can also occur. Recently, mutations in theAIP(aryl hydrocarbon receptor interacting protein) gene have been found to occur in 30–50% of FIPA patients, while for the rest of the patients the gene causing the disease is currently unknown and is a topic of intense research. Tumours in patients withAIPmutations are diagnosed at significantly younger ages and tend to be larger. Often the response to medical therapy in these patients is poor. This article discusses the clinical and genetic characteristics of this relatively recently recognised disease.

Characteristics of familial isolated pituitary adenomas

The familial occurrence of pituitary adenomas has been recognized for many years and currently accounts for approximately 5% of all cases. Molecular, genetic and clinical features of familial pituitary adenomas have been well characterized in multiple endocrine neoplasia type 1 (MEN-1) and Carney’s complex (CNC), which account for the majority of familial pituitary tumor cases. These conditions are caused by MEN1 and PRKAR1A gene mutations, respectively, and the clinical and pathological features of pituitary pathology in these diseases differ from those of sporadic pituitary tumors. Familial acromegaly has been recognized for many years and, more recently, the clinical features of this clinical phenotype, referred to as isolated familial somatotropinoma, have been clarified. Over the past decade, the concept of non-MEN-1/CNC familial pituitary tumors has been expanded significantly to include all phenotypes, a condition known as familial isolated pituitary adenomas (FIPA). In FIPA, tumors can present homogeneously (same phenotype) or heterogeneously (different tumor phenotypes) within the same family. Compared with sporadic pituitary adenomas, patients with FIPA have a younger age at diagnosis and have larger tumors. The clinical features of FIPA differ from those of MEN-1 in terms of a higher frequency of somatotropinomas and a lower frequency of prolactinomas. The recent discovery of the involvement of mutations in the aryl hydrocarbon receptor interacting protein (AIP) gene in association with pituitary tumors has provided new information regarding potential mechanisms of tumorigenesis in FIPA patients. While very infrequent in sporadic pituitary tumors, approximately 15% of FIPA patients have AIP mutations, rising to half of patients with familial acromegaly. In this review, we detail the clinical features of FIPA and discuss tumor pathology and genetic findings in this increasingly recognized clinical condition.