Liliya Rostomyan

X-linked acrogigantism syndrome: clinical profile and therapeutic responses.

X-linked acrogigantism (X-LAG) is a new syndrome of pituitary gigantism, caused by microduplications on chromosome Xq26.3, encompassing the gene GPR101, which is highly upregulated in pituitary tumors. We conducted this study to explore the clinical, radiological, and hormonal phenotype and responses to therapy in patients with X-LAG syndrome. The study included 18 patients (13 sporadic) with X-LAG and microduplication of chromosome Xq26.3. All sporadic cases had unique duplications and the inheritance pattern in two families was dominant, with all Xq26.3 duplication carriers being affected. Patients began to grow rapidly as early as 2-3 months of age (median 12 months). At diagnosis (median delay 27 months), patients had a median height and weight standard deviation scores (SDS) of >+3.9 SDS. Apart from the increased overall body size, the children had acromegalic symptoms including acral enlargement and facial coarsening. More than a third of cases had increased appetite. Patients had marked hypersecretion of GH/IGF1 and usually prolactin, due to a pituitary macroadenoma or hyperplasia. Primary neurosurgical control was achieved with extensive anterior pituitary resection, but postoperative hypopituitarism was frequent. Control with somatostatin analogs was not readily achieved despite moderate to high levels of expression of somatostatin receptor subtype-2 in tumor tissue. Postoperative use of adjuvant pegvisomant resulted in control of IGF1 in all five cases where it was employed. X-LAG is a new infant-onset gigantism syndrome that has a severe clinical phenotype leading to challenging disease management.

Clinical and genetic characterization of pituitary gigantism: an international collaborative study in 208 patients

Despite being a classical growth disorder, pituitary gigantism has not been studied previously in a standardized way. We performed a retrospective, multicenter, international study to characterize a large series of pituitary gigantism patients. We included 208 patients (163 males; 78.4%) with growth hormone excess and a current/previous abnormal growth velocity for age or final height >2 s.d. above country normal means. The median onset of rapid growth was 13 years and occurred significantly earlier in females than in males; pituitary adenomas were diagnosed earlier in females than males (15.8 vs 21.5 years respectively). Adenomas were ≥10 mm (i.e., macroadenomas) in 84%, of which extrasellar extension occurred in 77% and invasion in 54%. GH/IGF1 control was achieved in 39% during long-term follow-up. Final height was greater in younger onset patients, with larger tumors and higher GH levels. Later disease control was associated with a greater difference from mid-parental height (r=0.23, P=0.02). AIP mutations occurred in 29%; microduplication at Xq26.3 - X-linked acrogigantism (X-LAG) - occurred in two familial isolated pituitary adenoma kindreds and in ten sporadic patients. Tumor size was not different in X-LAG, AIP mutated and genetically negative patient groups. AIP-mutated and X-LAG patients were significantly younger at onset and diagnosis, but disease control was worse in genetically negative cases. Pituitary gigantism patients are characterized by male predominance and large tumors that are difficult to control. Treatment delay increases final height and symptom burden. AIP mutations and X-LAG explain many cases, but no genetic etiology is seen in >50% of cases.

Somatic mosaicism underlies X-linked acrogigantism syndrome in sporadic male subjects

Somatic mosaicism has been implicated as a causative mechanism in a number of genetic and genomic disorders. X-linked acrogigantism (XLAG) syndrome is a recently characterized genomic form of pediatric gigantism due to aggressive pituitary tumors that is caused by submicroscopic chromosome Xq26.3 duplications that include GPR101 We studied XLAG syndrome patients (n= 18) to determine if somatic mosaicism contributed to the genomic pathophysiology. Eighteen subjects with XLAG syndrome caused by Xq26.3 duplications were identified using high-definition array comparative genomic hybridization (HD-aCGH). We noted that males with XLAG had a decreased log2ratio (LR) compared with expected values, suggesting potential mosaicism, whereas females showed no such decrease. Compared with familial male XLAG cases, sporadic males had more marked evidence for mosaicism, with levels of Xq26.3 duplication between 16.1 and 53.8%. These characteristics were replicated using a novel, personalized breakpoint junction-specific quantification droplet digital polymerase chain reaction (ddPCR) technique. Using a separate ddPCR technique, we studied the feasibility of identifying XLAG syndrome cases in a distinct patient population of 64 unrelated subjects with acromegaly/gigantism, and identified one female gigantism patient who had had increased copy number variation (CNV) threshold for GPR101 that was subsequently diagnosed as having XLAG syndrome on HD-aCGH. Employing a combination of HD-aCGH and novel ddPCR approaches, we have demonstrated, for the first time, that XLAG syndrome can be caused by variable degrees of somatic mosaicism for duplications at chromosome Xq26.3. Somatic mosaicism was shown to occur in sporadic males but not in females with XLAG syndrome, although the clinical characteristics of the disease were similarly severe in both sexes.

GHRH excess and blockade in X-LAG syndrome

X-linked acrogigantism (X-LAG) syndrome is a newly described form of inheritable pituitary gigantism that begins in early childhood and is usually associated with markedly elevated GH and prolactin secretion by mixed pituitary adenomas/hyperplasia. Microduplications on chromosome Xq26.3 including the GPR101 gene cause X-LAG syndrome. In individual cases random GHRH levels have been elevated. We performed a series of hormonal profiles in a young female sporadic X-LAG syndrome patient and subsequently undertook in vitro studies of primary pituitary tumor culture following neurosurgical resection. The patient demonstrated consistently elevated circulating GHRH levels throughout preoperative testing, which was accompanied by marked GH and prolactin hypersecretion; GH demonstrated a paradoxical increase following TRH administration. In vitro, the pituitary cells showed baseline GH and prolactin release that was further stimulated by GHRH administration. Co-incubation with GHRH and the GHRH receptor antagonist, acetyl-(d-Arg(2))-GHRH (1-29) amide, blocked the GHRH-induced GH stimulation; the GHRH receptor antagonist alone significantly reduced GH release. Pasireotide, but not octreotide, inhibited GH secretion. A ghrelin receptor agonist and an inverse agonist led to modest, statistically significant increases and decreases in GH secretion, respectively. GHRH hypersecretion can accompany the pituitary abnormalities seen in X-LAG syndrome. These data suggest that the pathology of X-LAG syndrome may include hypothalamic dysregulation of GHRH secretion, which is in keeping with localization of GPR101 in the hypothalamus. Therapeutic blockade of GHRH secretion could represent a way to target the marked hormonal hypersecretion and overgrowth that characterizes X-LAG syndrome.

McCune-Albright Syndrome: A Detailed Pathological And Genetic Analysis of Disease Effects in an Adult Patient.

CONTEXT McCune Albright syndrome (MAS) is a clinical association of endocrine and nonendocrine anomalies caused by postzygotic mutation of the GNAS1 gene, leading to somatic activation of the stimulatory α-subunit of G protein (Gsα). Important advances have been made recently in describing pathological characteristics of many MAS-affected tissues, particularly pituitary, testicular, and adrenal disease. Other rarer disease related features are emerging. OBJECTIVE The objective of the investigation was to study the pathological and genetic findings of MAS on a tissue-by-tissue basis in classically and nonclassically affected tissues. DESIGN This was a comprehensive autopsy and genetic analysis. SETTING The study was conducted at a tertiary referral university hospital. PATIENTS An adult male patient with MAS and severe disease burden including gigantism was the subject of the study. INTERVENTION(S) Interventions included clinical, hormonal, and radiographic studies and gross and microscopic pathology analyses, conventional PCR, and droplet digital PCR analyses of affected and nonaffected tissues. MAIN OUTCOME MEASURE Pathological findings and the presence of GNAS1 mutations were measured. RESULTS The patient was diagnosed with MAS syndrome at 6 years of age based on the association of café-au-lait spots and radiological signs of polyostotic fibrous dysplasia. Gigantism developed and hyperprolactinemia, hypogonadotropic hypogonadism, and hyperparathyroidism were diagnosed throughout the adult period. The patient died at the age of 39 years from a pulmonary embolism. A detailed study revealed mosaiscism for the p.R201C GNAS1 mutation distributed across many endocrine and nonendocrine tissues. These genetically implicated tissues included rare or previously undescribed disease associations including primary hyperparathyroidism and hyperplasia of the thymus and endocrine pancreas. CONCLUSIONS This comprehensive pathological study of a single patient highlights the complex clinical profile of MAS and illustrates important advances in understanding the characteristics of somatic GNAS1-related pathology across a wide range of affected organs.

Pituitary gigantism: Causes and clinical characteristics

Acromegaly and pituitary gigantism are very rare conditions resulting from excessive secretion of growth hormone (GH), usually by a pituitary adenoma. Pituitary gigantism occurs when GH excess overlaps with the period of rapid linear growth during childhood and adolescence. Until recently, its etiology and clinical characteristics have been poorly understood. Genetic and genomic causes have been identified in recent years that explain about half of cases of pituitary gigantism. We describe these recent discoveries and focus on some important settings in which gigantism can occur, including familial isolated pituitary adenomas (FIPA) and the newly described X-linked acrogigantism (X-LAG) syndrome.

Overview of genetic testing in patients with pituitary adenomas.

Clinically-relevant pituitary adenomas occur with a prevalence of one case per 1000-1300 of the general population. Although most are sporadic, there are several inherited conditions that incur an increased risk of developing a pituitary adenoma. Multiple endocrine neoplasia type 1 and Carney complex (due to mutations in MEN1 and PRKAR1A, respectively) are established pituitary adenoma predisposition conditions, while multiple endocrine neoplasia type 4 (due to CDKN1B mutations) is an emerging rare condition. Familial isolated pituitary adenomas (FIPA) is a novel condition not associated with these multiple endocrine neoplasias. Mutations in the aryl hydrocarbon receptor interacting protein gene account for about 15% of FIPA kindreds and are associated with about 10-20% of macroadenomas that occur in children, adolescents and young adults. When treating a pituitary adenoma patient, relevant familial and clinical factors such as associated tumors or syndromic features should be assessed at the outset in order to guide the correct choice of genetic testing in appropriate individuals.

Paleogenetic study of ancient DNA suggestive of X-Linked acrogigantism

Pituitary gigantism is caused by chronic growth hormone (GH) hypersecretion by a pituitary lesion before epiphyseal fusion. Genetic causes have been identified in nearly 50% of patients with pituitary gigantism, with germline mutations in the AIP gene being the most frequent cause (Rostomyan et al. 2015). Recently, a new form of pituitary gigantism, X-linked acrogigantism (X-LAG), was described (Trivellin et al. 2014). X-LAG is due to chromosome Xq26.3 duplication, and GPR101 is the disease-associated gene (Trivellin et al. 2014, Iacovazzo et al. 2016). X-LAG is characterized by mixed GH/prolactin-secreting pituitary macroadenomas and/or hyperplasia in early childhood (Beckers et al. 2015). X-LAG typically occurs sporadically in females, but somatic mosaicism also occurs in males; familial mother-to-son transmission of the Xq26.3 duplication has been reported in three familial isolated pituitary adenoma families (Trivellin et al. 2014, Daly et al. 2016, Gordon et al. 2016, Iacovazzo et al. 2016). The clinical presentation of X-LAG syndrome differs from other genetic forms of pituitary gigantism (Rostomyan et al. 2015), and many well-known historical cases of gigantism share the clinical characteristics of X-LAG syndrome (Beckers et al. 2015, Rostomyan et al. 2015). If untreated during childhood, X-LAG leads to established extreme gigantism (>1.9 m) before puberty (Daly et al. 2016). We studied a historical case of severe acrogigantism. The subject, J.K., was born in 1872 in Reutlingen, in what is now Baden-Württemberg, Germany. His parents and brother were of normal size. It was reported by his doctor that J.K. had always been ‘very large’ and he was reputed to have a huge appetite; he measured 1.94 m at the age of 14 and never stopped growing thereafter (Launois & Roy 1904). In contemporary Württemberg, the average adult male height was only 164 cm. By the 1890s he was exhibiting himself as Giant Constantine/Le Geant Constantin (Fig. 1A). In 1898, he was 259 cm in height (8 feet 6 inches) and weighted 168 kg (370 pounds). He fell ill while in the Walloon region of Belgium and was hospitalized on November 15, 1901, at the Hôpital Civil in Mons, Belgium with a fever (39.3°C) due to severe lower limb gangrene. Hospital records show his height as 256 cm and weight as 180 kg. He improved initially after an amputation of the right leg, but the following year, he fell and the other leg was amputated below the knee. He developed post-operative septicemia and died on March 30, 1902. At autopsy, the pituitary was grossly enlarged to the size of ‘a large walnut’ (Launois & Roy 1904). The sella turcica was also greatly enlarged, so much so that it was remarked that ‘after removing the cerebral hemispheres and the cerebellum, the sella was so broad and deep that it brought to mind two juxtaposed spinal canals’ (Launois & Roy 1904) (Fig. 1B and C). The long bones and extremities were elongated, and the proximal humeral epiphyses remained unfused (Launois & Roy 1904). Concomitant hypogonadism (testicular atrophy) was present on examination and post-mortem. Current forensic analysis of the skeleton demonstrates bleaching of the bones consistent with reported preservation by prolonged boiling. Given the clinical history of early-onset acrogigantism, an underlying genetic cause was thought to be likely. DNA extraction from teeth was unreliable as the skull was edentulous when originally photographed in 1904 (Launois & Roy 1904); subsequently, teeth were added to the skull but they could not be confirmed as having been obtained from the subject himself. The skeleton was fragile after preservation by prolonged boiling, and DNA extractions from a metatarsal and the femur were unsuccessful. Based on results obtained from ancient skeletal remains, tissue from the cochlea was obtained via the petrous temporal bone (Pinhasi et al. 2015) as reported in Supplemental materials (see section on supplementary data given at the end of this article). His history of earlyonset, severe pituitary gigantism led us to suspect X-LAG (Trivellin et al. 2014, Daly et al. 2016). The DNA sample was assayed using a ddPCR technique as previously described (Daly et al. 2016). Briefly, the ddPCR compared copy number variations (CNV) at the GPR101 gene as compared with ZIC3, a gene that is not duplicated in X-LAG syndrome. Daly and coworkers recently showed this method was 24:2 Research Letter A Beckers et al. Historical XLAG syndrome

Intensity of prolactinoma on T2-weighted magnetic resonance imaging: towards another gender difference

IntroductionClinical presentations of prolactinomas are quite different between genders. In comparison with women’s prolactinoma, those in men showed predominance of large tumors with high prolactin (PRL) levels. This preponderance could be attributed to a greater proliferative potential of the tumors.Differences in magnetic resonance imaging (MRI) signal at diagnosis have not been yet clearly evaluated.MethodsWe conduct a retrospective study comparing MRI signal intensity (SI) on T2-weighted images (T2-WI) between 41 men and 41 women to investigate whether or not men prolactinoma present specific features.ResultsIn addition to the size of the adenoma and PRL levels (P < 0001), prolactinomas in men also exhibit differences from those in women in signal on T2-WI on MRI (P < 0001). Women’s prolactinomas are mostly of high SI on T2-WI while men’s prolactinomas exhibit a more heterogeneous pattern of SI on T2-WI. Prolactinomas presenting with low SI on T2-WI are almost exclusively encountered in men.ConclusionsPresence of T2-WI hypointensities in pituitary adenoma can be predictive of a different subtype of prolactinoma almost encountered in men and possibly translate the presence of spherical amyloid deposits, in agreement with the literature.

Screening for genetic causes of growth hormone hypersecretion.

Growth hormone (GH) secreting pituitary tumors may be caused by genetic abnormalities in a variety of genes including AIP, MEN1, CDKN1B, and PRKAR1A. These can lead to GH secreting pituitary adenomas as an isolated occurrence (e.g. as aggressive sporadic adenomas or in familial isolated pituitary adenomas (FIPA)) or as part of syndromic conditions such as MEN1 or Carney complex. These tumors have more aggressive features than sporadic acromegaly, including a younger age at disease onset and larger tumor size, and they can be challenging to manage. In addition to mutations or deletions, copy number variation at the GPR101 locus may also lead to mixed GH and prolactin secreting pituitary adenomas in the setting of X-linked acrogigantism (X-LAG syndrome). In X-LAG syndrome and in McCune Albright syndrome, mosaicism for GPR101 duplications and activating GNAS1 mutations, respectively, contribute to the genetic pathogenesis. As only 5% of pituitary adenomas have a known cause, efficient deployment of genetic testing requires detailed knowledge of clinical characteristics and potential associated syndromic features in the patient and their family.