Isolated Macroprolactinomas in Four Young Adult Males Harboring a Variant of the Aryl Hydrocarbon Interacting Protein (AIP) Gene: Isn’t It Too Much of a Coincidence?

Background: Germline mutations in the Aryl hydrocarbon receptor-Interacting Protein (AIP) gene are associated with pituitary adenomas in young patients usually in the setting of Familial Isolated Pituitary Adenomas (FIPA). The majority of these adenomas are somatotropinomas followed by prolactinomas, and rarely non-secreting adenomas. AIP-mutation-related prolactinomas predominantly affect men, as opposed to sporadic prolactinomas, that typically affect women. Clinical Case: We previously described an AIP gene mutation in two patients affected by prolactinomas. During the past years, we continued our study and have identified two more male patients with macroprolactinomas originally from the same small village and harboring the same AIP gene mutation. These male patients aged 19 to 44 years at the time of diagnosis. Two of them had neurological manifestations as the first clinical manifestation of the disease, one was studied because of hypogonadism and two patients had visual field defects. All of them had prolactin levels above 1000 ng/dl (mean 2946.5±948.7 ng/dl, reference range 10-21). In the imaging exams (CT/MRI) they presented pituitary adenomas larger than 20 mm (macroprolactinomas) and in two of the cases, the adenomas were even larger than 40 mm (giant prolactinomas). In order to exclude mutations most often associated with prolactinomas, DNA samples were obtained and analyzed by Next Generation Sequencing (NGS) using TruSightCancer Gene Set (Illumina) methodology. Investigation of significant deletions and/or duplications was performed using the MLPA (Multiplex ligation-dependent probe amplification) technique. None of the patients were positive for mutations of Multiple Endocrine Neoplasia type 1 (MEN1) gene. A variant of the AIP gene c.47G>A, expecting to lead to a substitution of arginine by histidine at position 16 (p.Arg16His) of the AIP was found in these four patients, including a father and his son. Seven asymptomatic carriers were identified among their first-degree relatives. In silico analysis and the information available in the literature, as well as in databases is not in agreement with the pathogenicity of this variant of the AIP gene. However, our findings point to a founder effect transmitted as a dominant trait with incomplete penetrance (4 out of 11 patients, 36%). Conclusion: The variant of the AIP gene identified in our patients behaved as a pathogenic mutation and was only associated with prolactinomas, including two giant prolactinomas.

Modern views on the genetic determinism of GH-secreting pituitary adenomas (literature review and own data)

Background. This article presents a review of the current literature on the role of the genetic component in the etiology and pathogenesis of hormone-active pituitary adenomas secreting growth hormone (GH) and clinically manifesting by acromegaly and/or gigantism (multiple endocrine neoplasia 1 (MEN-1), McCune-Albright syndrome, Carney complex, X-linked acrogigantism (X-LAG), familial isolated pituitary adenoma — FIPA). Materials and methods. To identify mutations in the AIP gene and to verify FIPA, 26 patients of the Ukrainian population (19 women and 7 men) were examined in whom acromegaly was diagnosed in adolescence or young age, and genetic analysis was performed. To determine the genetic determinism in the development of GH-secreting pituitary adenoma and differential diagnosis of FIPA and MEN-1 syndromes by sequencing method (MLPA — ligation-dependent probe amplification), the genes MLPA, P244-C1 were studied involving exons 1–6 MEN1 gene, (MLPA, P017-D1) AIP gene. Results. Among those examined, only two patients had AIP gene mutations. In one patient, genetic screening for MEN1 gene mutation was negative and no clinical symptoms suggestive of McCune-Albright syndrome were detected. A variant heterozygous missense c.714C>G (p.Cys238Trp) was found in the AIP gene. This AIP gene assay is compatible with a genetic predisposition to develop pituitary adenoma. The offspring of this patient has a 50% chance of inheriting this variant, acromegaly, hypersomatotropinemia, MEN-1 syndrome, familial isolated pituitary adenoma. Another patient was diagnosed with MEN syndrome type 1 (Wermer syndrome): insulinoma, parathyroid gland adenomas (2), primary hyperparathyroidism with a heterozygous c.134A>G variant (p.Glu45Gly) found in the MEN1 gene. The presence of the c.l34A>G (p.Glu45Gly) class variant 4 is likely to be pathogenic. The prevalence of this variant in the general population is unknown, so it is very rare. Conclusions. The genetic analysis is appropriate in pediatric and young patients or those with GH-secreting macro/giant pituitary adenoma diagnosed at a young age (under 35), regardless of family history. In patients with a history of a disease, genetic analysis is recommended in any case to identify FIPA and to predict the further course of the disease and the effectiveness of treatment with somatostatin analogues.

Pituitary Disease in AIP Mutation-Positive Familial Isolated Pituitary Adenoma (FIPA): A Kindred-Based Overview

Clinically-relevant pituitary adenomas occur in about 1:1000 of the general population, but only about 5% occur in a known genetic or familial setting. Familial isolated pituitary adenomas (FIPA) are one of the most important inherited settings for pituitary adenomas and the most frequent genetic cause is a germline mutation in the aryl hydrocarbon receptor-interacting protein (AIP) gene. AIP mutations lead to young-onset macroadenomas that are difficult to treat. Most are growth hormone secreting tumors, but all other secretory types can exist and the clinical profile of affected patients is variable. We present an overview of the current understanding of AIP mutation-related pituitary disease and illustrate various key clinical factors using examples from one of the largest AIP mutation-positive FIPA families identified to date, in which six mutation-affected members with pituitary disease have been diagnosed. We highlight various clinically significant features of FIPA and AIP mutations, including issues related to patients with acromegaly, prolactinoma, apoplexy and non-functioning pituitary adenomas. The challenges faced by these AIP mutation-positive patients due to their disease and the long-term outcomes in older patients are discussed. Similarly, the pitfalls encountered due to incomplete penetrance of pituitary adenomas in AIP-mutated kindreds are discussed.

Clinical and Molecular Update on Genetic Causes of Pituitary Adenomas

Pituitary adenomas are benign tumors with variable functional characteristics that can have a significant impact on patients. The majority arise sporadically, but an inherited genetic susceptibility is increasingly being recognized. Recent advances in genetics have widened the scope of our understanding of pituitary tumorigenesis. The clinical and genetic characteristics of pituitary adenomas that develop in the setting of germline-mosaic and somatic GNAS mutations (McCune–Albright syndrome and sporadic acromegaly), germline MEN1 mutations (multiple endocrine neoplasia type 1), and germline PRKAR1A mutations (Carney complex) have been well described. Non-syndromic familial cases of isolated pituitary tumors can occur as familial isolated pituitary adenomas (FIPA); mutations/deletions of the AIP gene have been found in a minority of these. Genetic alterations in GPR101 have been identified recently as causing X-linked acro-gigantism (X-LAG) leading to very early-onset pediatric gigantism. Associations of pituitary adenomas with other tumors have been described in syndromes like multiple endocrine neoplasia type 4, pheochromocytoma-paraganglioma with pituitary adenoma association (3PAs) syndrome and some of their genetic causes have been elucidated. The genetic etiologies of a significant proportions of sporadic corticotropinomas have recently been identified with the discovery of USP8 and USP48 mutations. The elucidation of genetic and molecular pathophysiology in pituitary adenomas is a key factor for better patient management and effective follow-up.

MON-300 AIP Gene Germline Mutations in Non-Selected Patients with Apparently Sporadic Pituitary Macrodenomas

Up to 5% of all pituitary tumors are hereditary (e.g. due to menin or AIP genes germline mutations). AIP gene mutations are more common in subjects with acromegaly, less than 30 years old at the onset of disease, and with FIPA family history. The study was aimed at the assessment of the frequency and characteristics of AIP-mutation related tumors in non-selected patients with pituitary macroadenomas. Material and methods. The study included subsequent 131 patients (57 males, 74 females; median age 42 years (IQR 25 years) diagnosed with pituitary macroadenomas, and with a negative family history of FIPA or MEN1 syndromes. The following tumors were identified: 11 ACTH-secreting, 49 GH-secreting (including 7 pluri-hormonal ones), 6 gonadotropinomas, 23 prolactinomas, 1 TSH-oma, and 43 non-secreting adenomas. Sanger sequencing was used for the assessment of AIP gene variants. The study was approved by the Ethics Board of JUMC. Results. An AIP mutation was identified in five of 131 included subjects (3.8%): one diagnosed with Cushing’s disease, two with acromegaly, and two with non-secreting adenomas. In two patients, the identified mutation usually predisposes to ACTH-secreting adenomas, in two patients - mutations of unknown clinical significance were found (usually connected with pituitary adenomas), and the mutation detected in one patient was described as benign. Patients harboring hereditary AIP gene variations did not differ from the rest of the study group in median age at diagnosis (41 vs. 42.5 years, p=0.8), median largest tumor diameter (25 vs. 24 mm, p=0.6), gender distribution (60% of females vs. 56.3%, p=0.8), secreting tumor frequency (60% vs. 67.5%, p=0.7), or acromegaly diagnosis frequency (40% vs.37.3%, p=0.9). 2 of the 5 patients with identified AIP gene mutations agreed for their families to be offered AIP genetic testing: (1) An AIP mutation was found in the asymptomatic mother of one acromegalic female patient. (2) The AIP mutation of unknown clinical significance was detected in the son of a male acromegalic patient with acromegaly, clinically unscreened yet. Conclusions. In our series of apparently sporadic pituitary macroadenomas, AIP gene mutation carriers did not differ substantially from patients with negative genetic testing. A risk factor-centered approach to AIP genetic screening may result in missing germline mutations, therefore, there is a need to establish if such a situation negatively impacts a patient’s and his/her family outcomes.

Significant Benefits of AIP Testing and Clinical Screening in Familial Isolated and Young-onset Pituitary Tumors

Context Germline mutations in the aryl hydrocarbon receptor-interacting protein (AIP) gene are responsible for a subset of familial isolated pituitary adenoma (FIPA) cases and sporadic pituitary neuroendocrine tumors (PitNETs). Objective To compare prospectively diagnosed AIP mutation-positive (AIPmut) PitNET patients with clinically presenting patients and to compare the clinical characteristics of AIPmut and AIPneg PitNET patients. Design 12-year prospective, observational study. Participants & Setting We studied probands and family members of FIPA kindreds and sporadic patients with disease onset ≤18 years or macroadenomas with onset ≤30 years (n = 1477). This was a collaborative study conducted at referral centers for pituitary diseases. Interventions & Outcome AIP testing and clinical screening for pituitary disease. Comparison of characteristics of prospectively diagnosed (n = 22) vs clinically presenting AIPmut PitNET patients (n = 145), and AIPmut (n = 167) vs AIPneg PitNET patients (n = 1310). Results Prospectively diagnosed AIPmut PitNET patients had smaller lesions with less suprasellar extension or cavernous sinus invasion and required fewer treatments with fewer operations and no radiotherapy compared with clinically presenting cases; there were fewer cases with active disease and hypopituitarism at last follow-up. When comparing AIPmut and AIPneg cases, AIPmut patients were more often males, younger, more often had GH excess, pituitary apoplexy, suprasellar extension, and more patients required multimodal therapy, including radiotherapy. AIPmut patients (n = 136) with GH excess were taller than AIPneg counterparts (n = 650). Conclusions Prospectively diagnosed AIPmut patients show better outcomes than clinically presenting cases, demonstrating the benefits of genetic and clinical screening. AIP-related pituitary disease has a wide spectrum ranging from aggressively growing lesions to stable or indolent disease course.

Surgery, Octreotide, Temozolomide, Bevacizumab, Radiotherapy, and Pegvisomant Treatment of an AIP Mutation‒Positive Child

Context Inactivating germline mutations in the aryl hydrocarbon receptor interacting protein (AIP) gene are linked to pituitary adenoma predisposition. Here, we present the youngest known patient with AIP-related pituitary adenoma. Case Description The patient presented at the age of 4 years with pituitary apoplexy and left ptosis with severe visual loss following a 1-year history of abdominal pain, headaches, and rapid growth. His IGF-1 level was 5× the upper limit of normal, and his random GH level was 1200 ng/mL. MRI showed a 43 × 24 × 35‒mm adenoma with suprasellar extension invading the left cavernous sinus (Knosp grade 4). After transsphenoidal surgery, histology showed a grade 2A sparsely granulated somatotropinoma with negative O6-methylguanine-DNA methyltransferase and positive vascular endothelial growth factor staining. Genetic testing identified a heterozygous germline nonsense AIP mutation (p.Arg81Ter). Exome sequencing of the tumor revealed that it had lost the entire maternal chromosome-11, rendering it hemizygous for chromosome-11 and therefore lacking functional copies of AIP in the tumor. He was started on octreotide, but because the tumor rapidly regrew and IGF-1 levels were unchanged, temozolomide was initiated, and intensity-modulated radiotherapy was administered 5 months after surgery. Two months later, bevacizumab was added, resulting in excellent tumor response. Although these treatments stabilized tumor growth over 4 years, IGF-1 was normalized only after pegvisomant treatment, although access to this medication was intermittent. At 3.5 years of follow-up, gamma knife treatment was administered, and pegvisomant dose increase was indicated. Conclusion Multimodal treatment with surgery, long-acting octreotide, radiotherapy, temozolomide, bevacizumab, and pegvisomant can control genetically driven, aggressive, childhood-onset somatotropinomas.