The Genetic Pathophysiology and Clinical Management of the TADopathy, X-Linked Acrogigantism

Pituitary gigantism is a rare manifestation of chronic growth hormone (GH) excess that begins before closure of the growth plates. Nearly half of pituitary gigantism patients have an identifiable genetic cause. X-linked acrogigantism (X-LAG; 10% of pituitary gigantism) typically begins during infancy and can lead to the tallest individuals described. In the 10 years since its discovery, about 40 patients have been identified. Patients with X-LAG usually develop mixed GH and prolactin macroadenomas with occasional hyperplasia that secrete copious amounts of GH, and frequently prolactin. Circulating GH releasing hormone (GHRH) is also elevated in a proportion of patients. X-LAG is caused by constitutive or sporadic mosaic duplications at chromosome Xq26.3 that disrupt the normal chromatin architecture of a topologically associating domain (TAD) around the orphan G protein coupled receptor (GPCR), GPR101. This leads to the formation of a neoTAD in which GPR101 over-expression is driven by ectopic enhancers ("TADopathy"). X-LAG has been seen in three families due to transmission of the duplication from affected mothers to sons. GPR101 is a constitutively active receptor with an unknown natural ligand that signals via multiple G proteins and protein kinases A and C to promote GH/prolactin hypersecretion. Treatment of X-LAG is challenging due to the young patient population and resistance to somatostatin analogs; the GH receptor antagonist pegvisomant is often an effective option. GH, insulin-like growth factor 1 (IGF-1) and prolactin hypersecretion and physical overgrowth can be controlled before definitive adult gigantism occurs, often at the cost of permanent hypopituitarism.

The evolution and ecology of gigantism in terror birds (Aves, Phorusrhacidae)

Terror birds (Aves, Phorusrhacidae) were large flightless apex predators in South America during the Cenozoic. Here, we estimate a new phylogeny for phorusrhacids using Bayesian inference. We demonstrate phylogenetic evidence for a monophyletic Patagornithinae and find significant support for a distinct crown group associated with the quintessential 'terror bird' characteristics. We use this phylogeny to analyse the evolution of body size and cursoriality. Our results reveal that size overlap was rare between co-occurring subfamilies, supporting the hypothesis that these traits were important for niche partitioning. We observe that gigantism evolved in a single clade, containing Phorusrhacinae and Physornithinae. The members of this lineage were consistently larger than all other phorusrhacids. Phorusrhacinae emerged following the extinction of Physornithinae, suggesting the ecological succession of the apex predator niche. The first known phorusrhacine, Phorusrhacos longissimus, was gigantic but significantly smaller and more cursorial than any physornithine. These traits likely evolved in response to the expansion of open environments. Following the Santacrucian SALMA, phorusrhacines increased in size, further converging on the morphology of Physornithinae. These findings suggest that the evolution and displacement of body size drove terror bird niche partitioning and competitive exclusion controlled phorusrhacid diversity.

A Potent Neutralizing Monoclonal Antibody to Human Growth Hormone Suppresses Insulin-Like Growth Factor-1 in Female Rats

Acromegaly and gigantism are disorders caused by hypersecretion of growth hormone (GH), usually from pituitary adenomas. Although somatostatin analogues (SSA), dopamine agonists, and GH receptor antagonists are important therapeutic agents, all of these have issues with their effectiveness, safety, and/or convenience of use. To overcome these, we developed a GH-specific potent neutralizing a mouse monoclonal antibody (mAb) named 13H02. 13H02 selectively bound both to human and monkey GH with high affinity, and strongly inhibited the biological activity of GH in the Nb2 rat lymphoma cell proliferation assay. In hypophysectomized/GH-supplemented rats, a single subcutaneous administration of 13H02 significantly and dose-dependently lowered the serum insulin-like growth factor-1 levels. To pursue the therapeutic potential of this antibody for acromegaly and gigantism, we humanized 13H02 to reduce its immunogenicity and applied a single amino acid mutation in the Fc region to extend its serum half-life. The resulting antibody, Hu-13H02m, also showed GH-specific neutralizing activity, similar to the parental 13H02, and showed improved binding affinity to human FcRn.

Genetic diagnosis in acromegaly and gigantism: From research to clinical practice

It is usually considered that only 5% of all pituitary neuroendocrine tumours are due to inheritable causes. Since this estimate was reported, however, multiple genetic defects driving syndromic and nonsyndromic somatotrophinomas have been unveiled. This heterogeneous genetic background results in overlapping phenotypes of GH excess. Genetic tests should be part of the approach to patients with acromegaly and gigantism because they can refine the clinical diagnoses, opening the possibility to tailor the clinical conduct to each patient. Even more, genetic testing and clinical screening of at-risk individuals have a positive impact on disease outcomes, by allowing for the timely detection and treatment of somatotrophinomas at early stages. Future research should focus on determining the actual frequency of novel genetic drivers of somatotrophinomas in the general population, developing up-to-date disease-specific multi-gene panels for clinical use, and finding strategies to improve access to modern genetic testing worldwide.

Tall stature and gigantism in adult patients with acromegaly

OBJECTIVES

Increased height in patients with acromegaly could be a manifestation of growth hormone (GH) excess before epiphysis closure. The aim of this study was to evaluate the relationship between the height of adult patients with GH excess related to mid-parental height (MPH) and population mean and to find whether taller patients with acromegaly come from tall families.

METHODS

This is a single-centre, observational study involving 135 consecutive patients with acromegaly diagnosed as adults and no family history of GH excess. We established three categories for height for patients with acromegaly: normal stature, tall stature (TS, height above the 97th percentile (1.88 standard deviations (SD)) to <3 SD for gender- and country-specific data or as a height which was greater than 1.5 SD but less than 2 SD above the MPH) and gigantism (height which was greater than 3 SD) above the gender- and country-specific mean or greater than 2 SD above MPH).

RESULTS

Thirteen percent (17/135) of patients (53% females) met the criteria for gigantism, 10% (14/135) fulfilled the criteria for TS (57% females). Parents and adult siblings were not taller than the population mean.

CONCLUSION

In a group of 135 consecutive adult patients with acromegaly, 23% had increased height based on country-specific and MPH data: 13% presented with gigantism while 10% had TS. The frequency of gigantism and TS in patients diagnosed with GH excess as adults is not higher in males than in females. Patients with acromegaly come from normal-stature families.

The ORGAN SIZE (ORG) locus modulates both vegetative and reproductive gigantism in domesticated tomato

BACKGROUND AND AIMS

Gigantism is a key component of the domestication syndrome, a suite of traits that differentiates crops from their wild relatives. Allometric gigantism is strongly marked in horticultural crops, causing disproportionate increases in the size of edible parts such as stems, leaves or fruits. Tomato (Solanum lycopersicum) has attracted attention as a model for fruit gigantism, and many genes have been described controlling this trait. However, the genetic basis of a corresponding increase in size of vegetative organs contributing to isometric gigantism has remained relatively unexplored.

METHODS

Here, we identified a 0.4-Mb region on chromosome 7 in introgression lines (ILs) from the wild species Solanum pennellii in two different tomato genetic backgrounds (cv. 'M82' and cv. 'Micro-Tom') that controls vegetative and reproductive organ size in tomato. The locus, named ORGAN SIZE (ORG), was fine-mapped using genotype-by-sequencing. A survey of the literature revealed that ORG overlaps with previously mapped quantitative trait loci controlling tomato fruit weight during domestication.

KEY RESULTS

Alleles from the wild species led to lower cell number in different organs, which was partially compensated by greater cell expansion in leaves, but not in fruits. The result was a proportional reduction in leaf, flower and fruit size in the ILs harbouring the alleles from the wild species.

CONCLUSIONS

Our findings suggest that selection for large fruit during domestication also tends to select for increases in leaf size by influencing cell division. Since leaf size is relevant for both source-sink balance and crop adaptation to different environments, the discovery of ORG could allow fine-tuning of these parameters.

Giant baleen whales emerged from a cold southern cradle

Baleen whales (mysticetes) include the largest animals on the Earth. How they achieved such gigantic sizes remains debated, with previous research focusing primarily on when mysticetes became large, rather than where. Here, we describe an edentulous baleen whale fossil (21.12-16.39 mega annum (Ma)) from South Australia. With an estimated body length of 9 m, it is the largest mysticete from the Early Miocene. Analysing body size through time shows that ancient baleen whales from the Southern Hemisphere were larger than their northern counterparts. This pattern seemingly persists for much of the Cenozoic, even though southern specimens contribute only 19% to the global mysticete fossil record. Our findings contrast with previous ideas of a single abrupt shift towards larger size during the Plio-Pleistocene, which we here interpret as a glacially driven Northern Hemisphere phenomenon. Our results highlight the importance of incorporating Southern Hemisphere fossils into macroevolutionary patterns, especially in light of the high productivity of Southern Ocean environments.

Innovative Reconstructive Management of Foot Macrodactyly in a Pediatric Patient: A Case Report

Macrodactyly is a rare congenital anomaly characterized by disproportionate hypertrophy of one or more digits or the forefoot, involving some or all tissue types. It is nonhereditary and can present alone or alongside other deformities. Usually, macrodactyly is treated with amputation of the affected toe or finger to reduce the chance of recurrence. In this paper, we present the case of a child with macrodactyly who was treated successfully without amputation and instead with a reconstruction of the toe shape to resemble a near-natural-looking toe with intact functions. The patient was a one-year-old female who presented with macrodactyly of her right great toe, right second toe, and forefoot. She had no history of other congenital deformities or systemic diseases. A reconstruction surgery was performed, which involved debulking the right great toe, right second toe, and forefoot. Also, it included the creation of the first web space and the restoration of the nailbed of the second toe. Postoperative follow-up revealed minimal complications. Thus, a second reconstructive surgery was performed, which included debulking and further reconstruction of the foot to improve the result. Several techniques exist for the reduction of macrodactyly that can achieve optimal results. The choice of technique depends on the specifics of the case and the experience of the surgeon. We therefore hope our technique will be beneficial for the management of future cases of macrodactyly. One year of follow-up after the second operation revealed maintained function and no regrowth recurrence.

Adaptive host responses to infection can resemble parasitic manipulation

Using a dynamic optimisation model for juvenile fish in stochastic food environments, we investigate optimal hormonal regulation, energy allocation and foraging behaviour of a growing host infected by a parasite that only incurs an energetic cost. We find it optimal for the infected host to have higher levels of orexin, growth and thyroid hormones, resulting in higher activity levels, increased foraging and faster growth. This growth strategy thus displays several of the fingerprints often associated with parasite manipulation: higher levels of metabolic hormones, faster growth, higher allocation to reserves (i.e. parasite-induced gigantism), higher risk-taking and eventually higher predation rate. However, there is no route for manipulation in our model, so these changes reflect adaptive host compensatory responses. Interestingly, several of these changes also increase the fitness of the parasite. Our results call for caution when interpreting observations of gigantism or risky host behaviours as parasite manipulation without further testing.

A new species of a giant tortoise from Sandelzhausen (MN5, Burdigalian/Langhian boundary, Early/Middle Miocene, South Germany)

We describe a new species of a giant tortoise of the genus Titanochelon from the locality of Sandelzhausen in south Germany (MN5, Burdigalian/Langhian boundary, Early/Middle Miocene). The material comprises at least two different individuals, one of which is a male individual preserving large parts of the carapace and plastron and several appendicular elements. The second individual is quite fragmented, preserving parts of the bridge and the posterior rim of the carapace. The new species, Titanochelon schleichi sp. nov., is the first species of a giant tortoise named from Germany and allows reconstructing an important diversity and expansion of titanochelones in the Western Palaearctic during the earlier parts of the Neogene.

Germline loss-of-function PAM variants are enriched in subjects with pituitary hypersecretion

Introduction

Pituitary adenomas (PAs) are common, usually benign tumors of the anterior pituitary gland which, for the most part, have no known genetic cause. PAs are associated with major clinical effects due to hormonal dysregulation and tumoral impingement on vital brain structures. PAM encodes a multifunctional protein responsible for the essential C-terminal amidation of secreted peptides.

Methods

Following the identification of a loss-of-function variant (p.Arg703Gln) in the peptidylglycine a-amidating monooxygenase (PAM) gene in a family with pituitary gigantism, we investigated 299 individuals with sporadic PAs and 17 familial isolated PA kindreds for PAM variants. Genetic screening was performed by germline and tumor sequencing and germline copy number variation (CNV) analysis.

Results

In germline DNA, we detected seven heterozygous, likely pathogenic missense, truncating, and regulatory SNVs. These SNVs were found in sporadic subjects with growth hormone excess (p.Gly552Arg and p.Phe759Ser), pediatric Cushing disease (c.-133T>C and p.His778fs), or different types of PAs (c.-361G>A, p.Ser539Trp, and p.Asp563Gly). The SNVs were functionally tested in vitro for protein expression and trafficking by Western blotting, splicing by minigene assays, and amidation activity in cell lysates and serum samples. These analyses confirmed a deleterious effect on protein expression and/or function. By interrogating 200,000 exomes from the UK Biobank, we confirmed a significant association of the PAM gene and rare PAM SNVs with diagnoses linked to pituitary gland hyperfunction.

Conclusion

The identification of PAM as a candidate gene associated with pituitary hypersecretion opens the possibility of developing novel therapeutics based on altering PAM function.

Effective Long-term Pediatric Pegvisomant Monotherapy to Final Height in X-linked Acrogigantism

X-linked acrogigantism (X-LAG) is characterized by extreme tall stature from early childhood resulting from duplication of the GPR101 gene, in turn resulting in GH excess. Most cases present with pituitary tumors secreting GH and prolactin. Diffuse pituitary hyperplasia is uncommon and normal prolactin is rare. We present a girl with tall stature from 3 years of age; her height was +4.25 SD score at 5 years, with no signs of syndromic disease. She had significant GH excess, serum IGF-1 4 times the upper limit of normal and normal circulating GHRH, with normal pituitary magnetic resonance imaging over 13 years. No abnormalities were found in either the AIP or MEN1 genes. Treatment with somatostatin analogues and dopamine agonists showed minimal therapeutic benefit, but significant side effects. She tested positive for duplication of GPR101 6 years after the initial diagnosis. She was then initiated on pegvisomant aged 12 years, achieving prompt IGF-1 normalization and growth cessation. Aged 16.5 years, she showed escape from IGF-1 control, and height velocity increased, but this responded well to a dose increase in pegvisomant, with reassuring long-term pediatric safety over 7 years. Her final height is +2.9 SD score. Currently, life-long pegvisomant treatment is planned with genetic counselling regarding future offspring.

Early Onset GH Excess: Somatotroph Adenoma in a Young Adult

GH-secreting pituitary adenomas can cause gigantism or acromegaly, determined by onset before or after epiphyseal fusion of the distal ends of the radius and ulna. Overlapping phenotypes can occur when the condition presents peripubertally. Gigantism is associated with identifiable hereditary causes and genetic mutations in almost 50% of cases; genetic testing should be considered in patients with gigantism and early-onset acromegaly, especially (but not only) when pituitary tumors have aggressive features and/or are refractory to standard treatments. Here, we present a case of a young adult with a giant somatotroph adenoma resistant to multiple treatment modalities and negative for mutations in AIP, which encodes aryl hydrocarbon receptor-interacting protein.

Atypical Course of a Patient With AIP-Positive Acromegaly: From GH Excess to GH Deficiency and Back to GH Excess

Acromegaly/giantism results from the chronic excess of growth hormone (GH) and insulin-like growth factor-1 (IGF-1), in more than 96% of cases, due to a GH-secreting pituitary adenoma. Primary treatment of choice is transsphenoidal resection of the adenoma. More than 30% to 40% of operated cases require adjunctive forms of treatment, be it pharmacological or radiotherapeutical. The multimodal treatment of acromegaly has resulted in substantial improvements in the quality of life and life expectancy of these patients. We herein present the complex case of a patient with acromegaly due to a mammosomatotrope adenoma, with a germ-line AIP (aryl hydrocarbon receptor-interacting protein) mutation, who had a chronic and protracted course of more than 15 years during which he was treated with surgery, somatostatin receptor ligands, dopamine agonist, and the GH receptor antagonist pegvisomant. At one point, he was able to come off medications and was even found to be transiently GH-deficient, only to develop acromegaly again after a couple of years.

Pediatric growth hormone and prolactin-secreting tumor associated with an AIP mutation and a MEN1 variant of uncertain significance

OBJECTIVES

Pituitary gigantism is a rare condition and it often has an identifiable genetic cause. In this article we report a case of a young girl with pituitary gigantism and two genetic changes.

CASE PRESENTATION

A 15-year-old girl with primary amenorrhea was diagnosed with a growth hormone (GH) and prolactin (PRL)-producing tumor, needing surgery and medical treatment with octreotide in order to achieve disease control. The co-occurrence of an AIP mutation and a MEN1 variant of uncertain significance was demonstrated in this patient. The germline mutation involving AIP was inherited from her father who at the age of 55 was unaffected and the MEN1 variant was a de novo duplication of the region 11q13.1. The latter variant, not previously reported, is unlikely to be pathogenic. Nonetheless, screening for other components of multiple endocrine neoplasia type 1 (MEN1) was performed and proved negative.

CONCLUSIONS

The rare co-occurrence of an AIP mutation and a MEN 1 variant of uncertain significance was demonstrated in this patient.

Germline loss-of-function PAM variants are enriched in subjects with pituitary hypersecretion

Pituitary adenomas (PAs) are common, usually benign tumors of the anterior pituitary gland which, for the most part, have no known genetic cause. PAs are associated with major clinical effects due to hormonal dysregulation and tumoral impingement on vital brain structures. Following the identification of a loss-of-function variant (p.Arg703Gln) in the PAM gene in a family with pituitary gigantism, we investigated 299 individuals with sporadic PAs and 17 familial isolated pituitary adenomas kindreds for PAM variants. PAM encodes a multifunctional protein responsible for the essential C-terminal amidation of secreted peptides. Genetic screening was performed by germline and tumor sequencing and germline copy number variation (CNV) analysis. No germline CNVs or somatic single nucleotide variants (SNVs) were identified. We detected seven likely pathogenic heterozygous missense, truncating, and regulatory SNVs. These SNVs were found in sporadic subjects with GH excess (p.Gly552Arg and p.Phe759Ser), pediatric Cushing disease (c.-133T>C and p.His778fs), or with different types of PAs (c.-361G>A, p.Ser539Trp, and p.Asp563Gly). The SNVs were functionally tested in vitro for protein expression and trafficking by Western blotting, for splicing by minigene assays, and for amidation activity in cell lysates and serum samples. These analyses confirmed a deleterious effect on protein expression and/or function. By interrogating 200,000 exomes from the UK Biobank, we confirmed a significant association of the PAM gene and rare PAM SNVs to diagnoses linked to pituitary gland hyperfunction. Identification of PAM as a candidate gene associated with pituitary hypersecretion opens the possibility of developing novel therapeutics based on altering PAM function.

Approach to the Patient With Pseudoacromegaly

Pseudoacromegaly encompasses a heterogeneous group of conditions in which patients have clinical features of acromegaly or gigantism, but no excess of GH or IGF-1. Acromegaloid physical features or accelerated growth in a patient may prompt referral to endocrinologists. Because pseudoacromegaly conditions are rare and heterogeneous, often with overlapping clinical features, the underlying diagnosis may be challenging to establish. As many of these have a genetic origin, such as pachydermoperiostosis, Sotos syndrome, Weaver syndrome, or Cantú syndrome, collaboration is key with clinical geneticists in the diagnosis of these patients. Although rare, awareness of these uncommon conditions and their characteristic features will help their timely recognition.

Predator cannibalism can shift prey community composition toward dominance by small prey species

Cannibalism among predators is a key intraspecific interaction affecting their density and foraging behavior, eventually modifying the strength of predation on heterospecific prey. Interestingly, previous studies showed that cannibalism among predators can increase or reduce predation on heterospecific prey; however, we know less about the factors that lead to these outcomes. Using a simple pond community consisting of Hynobius retardatus salamander larvae and their associated prey, I report empirical evidence that cannibalism among predators can increase predation on large heterospecific prey but reduce that on small heterospecific prey. In a field-enclosure experiment in which I manipulated the occurrence of salamander cannibalism, I found that salamander cannibalism increased predation on frog tadpoles but reduced that on aquatic insects simultaneously. The contrasting effects are most likely to be explained by prey body size. In the study system, frog tadpoles were too large for non-cannibal salamanders to consume, while aquatic insects were within the non-cannibals' consumable prey size range. However, when cannibalism occurred, a few individuals that succeeded in cannibalizing reached large enough size to consume frog tadpoles. Consequently, although cannibalism among salamanders reduced their density, salamander cannibalism increased predation on large prey frog tadpoles. Meanwhile, salamander cannibalism reduced predation on small prey aquatic insects probably because of a density reduction of non-cannibals primarily consuming aquatic insects. Body size is often correlated with various ecological traits, for instance, diet width, consumption, and excretion rates, and is thus considered a good indicator of species' effects on ecosystem function. All this considered, cannibalism among predators could eventually affect ecosystem function by shifting the size composition of the prey community.

Neurofibromatosis Type 1 Has a Wide Spectrum of Growth Hormone Excess

Overgrowth due to growth hormone (GH) excess affects approximately 10% of patients with neurofibromatosis type 1 (NF1) and optic pathway glioma (OPG). Our aim is to describe the clinical, biochemical, pathological, and genetic features of GH excess in a retrospective case series of 10 children and adults with NF1 referred to a tertiary care clinical research center. Six children (median age = 4 years, range of 3−5 years), one 14-year-old adolescent, and three adults (median age = 42 years, range of 29−52 years) were diagnosed with NF1 and GH excess. GH excess was confirmed by the failure to suppress GH (<1 ng/mL) on oral glucose tolerance test (OGTT, n = 9) and frequent overnight sampling of GH levels (n = 6). Genetic testing was ascertained through targeted or whole-exome sequencing (n = 9). Five patients (all children) had an OPG without any pituitary abnormality, three patients (one adolescent and two adults) had a pituitary lesion (two tumors, one suggestive hyperplasia) without an OPG, and two patients (one child and one adult) had a pituitary lesion (a pituitary tumor and suggestive hyperplasia, respectively) with a concomitant OPG. The serial overnight sampling of GH levels in six patients revealed abnormal overnight GH profiling. Two adult patients had a voluminous pituitary gland on pituitary imaging. One pituitary tumor from an adolescent patient who harbored a germline heterozygous p.Gln514Pro NF1 variant stained positive for GH and prolactin. One child who harbored a heterozygous truncating variant in exon 46 of NF1 had an OPG that, when compared to normal optic nerves, stained strongly for GPR101, an orphan G protein-coupled receptor causing GH excess in X-linked acrogigantism. We describe a series of patients with GH excess and NF1. Our findings show the variability in patterns of serial overnight GH secretion, somatotroph tumor or hyperplasia in some cases of NF1 and GH excess. Further studies are required to ascertain the link between NF1, GH excess and GPR101, which may aid in the characterization of the molecular underpinning of GH excess in NF1.

Duplications disrupt chromatin architecture and rewire GPR101-enhancer communication in X-linked acrogigantism

X-linked acrogigantism (X-LAG) is the most severe form of pituitary gigantism and is characterized by aggressive growth hormone (GH)-secreting pituitary tumors that occur in early childhood. X-LAG is associated with chromosome Xq26.3 duplications (the X-LAG locus typically includes VGLL1, CD40LG, ARHGEF6, RBMX, and GPR101) that lead to massive pituitary tumoral expression of GPR101, a novel regulator of GH secretion. The mechanism by which the duplications lead to marked pituitary misexpression of GPR101 alone was previously unclear. Using Hi-C and 4C-seq, we characterized the normal chromatin structure at the X-LAG locus. We showed that GPR101 is located within a topologically associating domain (TAD) delineated by a tissue-invariant border that separates it from centromeric genes and regulatory sequences. Next, using 4C-seq with GPR101, RBMX, and VGLL1 viewpoints, we showed that the duplications in multiple X-LAG-affected individuals led to ectopic interactions that crossed the invariant TAD border, indicating the existence of a similar and consistent mechanism of neo-TAD formation in X-LAG. We then identified several pituitary active cis-regulatory elements (CREs) within the neo-TAD and demonstrated in vitro that one of them significantly enhanced reporter gene expression. At the same time, we showed that the GPR101 promoter permits the incorporation of new regulatory information. Our results indicate that X-LAG is a TADopathy of the endocrine system in which Xq26.3 duplications disrupt the local chromatin architecture forming a neo-TAD. Rewiring GPR101-enhancer interaction within the new regulatory unit is likely to cause the high levels of aberrant expression of GPR101 in pituitary tumors caused by X-LAG.

A new method to calculate limb phase from trackways reveals gaits of sauropod dinosaurs

Limb phase, the timing of the footfalls in quadrupedal locomotion that describes common gaits such as the trot and the pace gait,^1,2 is widely believed to be difficult or even impossible to estimate for extinct tetrapods.^3-5 We here present a fundamentally new approach that allows for estimating limb phase based on variation patterns in long trackways. The approach is tested on trackways of modern mammals, where the estimates generally correspond well with the actually employed limb phase. We then estimate limb phases of giant wide-gauged sauropod dinosaurs based on three long trackways from the Lower Cretaceous of Arkansas, US.^6,7 Gait selection at the largest body sizes is of considerable interest given the lack of modern analogs. Contrary to previous assumptions,^8,9 our estimates suggest lateral sequence diagonal couplet walks, in which the footfalls of the diagonal limb pairs (e.g., right hind and left fore) are more closely related in time than those of the same side of the body (e.g., right hind and right fore). Such a gait selection allows for efficient walking while maintaining diagonal limb support throughout the step cycle, which is important for a giant, wide-gauged trackmaker.¹⁰ Estimations of limb phase may help to constrain other gait parameters, body size and shape, and, finally, potential trackmaker taxa.

Pseudo-pheochromocytoma due to obstructive sleep apnea: a case report

SUMMARY

Obstructive sleep apnea (OSA) is a condition of intermittent nocturnal upper airway obstruction. OSA increases sympathetic drive which may result in clinical and biochemical features suggestive of pheochromocytoma. We present the case of a 65-year-old male with a 2.9-cm left adrenal incidentaloma on CT, hypertension, symptoms of headache, anxiety and diaphoresis, and persistently elevated 24-h urine norepinephrine (initially 818 nmol/day (89-470)) and normetanephrine (initially 11.2 µmol/day (0.6-2.7)). He was started on prazosin and underwent left adrenalectomy. Pathology revealed an adrenal corticoadenoma with no evidence of pheochromocytoma. Over the next 2 years, urine norepinephrine and normetanephrine remained significantly elevated with no MIBG avid disease. Years later, he was diagnosed with severe OSA and treated with continuous positive airway pressure. Urine testing done once OSA was well controlled revealed complete normalization of urine norepinephrine and normetanephrine with substantial symptom improvement. It was concluded that the patient never had a pheochromocytoma but rather an adrenal adenoma with biochemistry and symptoms suggestive of pheochromocytoma due to untreated severe OSA. Pseudo-pheochromocytoma is a rare presentation of OSA and should be considered on the differential of elevated urine catecholamines and metanephrines in the right clinical setting.

LEARNING POINTS

Obstructive sleep apnea (OSA) is a common condition among adults. OSA may rarely present as pseudo-pheochromocytoma with symptoms of pallor, palpitations, perspiration, headache, or anxiety. OSA should be considered on the differential of elevated urine catecholamines and metanephrines, especially in patients with negative metaiodobenzylguanidine (MIBG) scan results.

The Internal Cranial Anatomy of a Female With Endocrine Disorders From a Mediaeval Population

Gigantism and acromegaly have been observed in past populations; however, analyses usually focus on the morphological features of the post-cranial skeleton. The aim of this study is to characterize the internal anatomical features of the skull (brain endocast anatomy and asymmetry, frontal pneumatization, cranial thickness, sella turcica size) of an adult individual from the 11-14th centuries with these two diseases, in comparison with non-pathological individuals from the same population. The material consisted of 33 adult skulls from a mediaeval population, one of them belonging to an adult female with endocrine disorders (OL-23/77). Based on the CT scans, the internal cranial anatomy was analysed. The sella turcica of OL-23/77 is much larger than in the comparative sample. The endocast of the individual OL-23/77 shows a left frontal/left occipital petalia, while the comparative population mostly had right frontal/left occipital petalias. The asymmetry in petalia location in OL-23/77 comes within the range of variation observed in the comparative population. The individual has high values for cranial thickness. The frontal sinuses of the specimen analysed are similar in size and shape to the comparative sample only for data scaled to the skull length. Enlarged sella turcica is typical for individuals with acromegaly/gigantism. The pattern of the left frontal/left occipital petalia in the specimen OL-23/77 is quite rare. The position of the endocranial petalias has not influenced the degree of asymmetry in the specimen. Despite the large bone thickness values, skull of OL-23/77 does not show any abnormal features. The skull/endocast relationship in this individual shows some peculiarities in relation to its large size, while other internal anatomical features are within the normal range of variation of the comparative sample.

Genetic data from the extinct giant rat from Tenerife (Canary Islands) points to a recent divergence from mainland relatives

Evolution of vertebrate endemics in oceanic islands follows a predictable pattern, known as the island rule, according to which gigantism arises in originally small-sized species and dwarfism in large ones. Species of extinct insular giant rodents are known from all over the world. In the Canary Islands, two examples of giant rats, †Canariomys bravoi and †Canariomys tamarani, endemic to Tenerife and Gran Canaria, respectively, disappeared soon after human settlement. The highly derived morphological features of these insular endemic rodents hamper the reconstruction of their evolutionary histories. We have retrieved partial nuclear and mitochondrial data from †C. bravoi and used this information to explore its evolutionary affinities. The resulting dated phylogeny confidently places †C. bravoi within the African grass rat clade (Arvicanthis niloticus). The estimated divergence time, 650 000 years ago (95% higher posterior densities: 373 000–944 000), points toward an island colonization during the Günz–Mindel interglacial stage. †Canariomys bravoi ancestors would have reached the island via passive rafting and then underwent a yearly increase of mean body mass calculated between 0.0015 g and 0.0023 g; this corresponds to fast evolutionary rates (in darwins (d), ranging from 7.09 d to 2.78 d) that are well above those observed for non-insular mammals.

Clinical characteristics and treatment outcomes in acromegaly, a retrospective single-center case series from Thailand

Introduction

acromegaly, an overproduction of growth hormone (GH), is associated with high rate of morbidity and mortality particularly in case of delayed in diagnosis and treatment. A wide variation of clinical presentations, treatment outcomes and morbidities have been reported.

Methods

a retrospective study was conducted to review clinical characteristics and treatment outcomes of patients with acromegaly treated in King Chulalongkorn Memorial Hospital, Bangkok, Thailand, between 2006 and 2018.

Results

eighty-four patients (31 males and 53 females) were reviewed, mean age at diagnosis was 45.7 ± 12.6 years (±SD), mean time of disease onset was 7.6 ± 6.4 years and mean follow-up period was 7.8 ± 5.3 years. The most common presenting symptoms were maxillofacial change (96.8%) and acral enlargement (94.7%). Hypertension (39.3%), diabetes mellitus (28.6%) and dyslipidemia (23.8%) were prevalent co-existing conditions. Four patients were identified having cancer at presentation; however, no additional malignancy was reported during the follow up. Most patients harbored macroadenomas, only 10 were found to have microadenomas. The outcomes of treatment were controlled disease in 70% of microadenoma and 64.9% of macroadenoma. Permanent loss of pituitary function was found in about 21.3% and there was one case reported of mortality. The logistic regression analysis for controlled disease outcome showed the IGF-I index after surgery was associated with controlled disease outcome with statistically significant result (P-value=0.006).

Conclusion

our study offers descriptive clinical data of case series of acromegalic patients, which had favorable outcomes comparable with previous reports. In addition, IGF-I index after surgery is a predictive parameter for outcome of treatment.

Clinical Characteristics and Management of Patients With McCune-Albright Syndrome With GH Excess and Precocious Puberty: A Case Series and Literature Review

Background

McCune-Albright syndrome is a rare disorder characterized by fibrous dysplasia, café au lait skin spots, and hyperfunctioning endocrinopathies. The coexistence of precocious puberty and growth hormone excess in McCune-Albright syndrome is rare. Both conditions can manifest as accelerated growth, and treatments can be more challenging for such patients. This study aimed to describe the clinical manifestations of combined GH excess and PP in the context of McCune-Albright syndrome and analyze the clinical features and treatments of these patients.

Method

Clinical data from 60 McCune-Albright syndrome patients from Peking Union Medical College Hospital were obtained. The demographic characteristics, growth hormone, insulin-like growth factor-1, prolactin, alkaline phosphatase, and sex hormone levels; growth velocity; and bone age data were obtained. The growth velocity Z-score, bone age over chronological age ratio, and predicted adult height Z-score were calculated before and after treatment. Published studies and case reports were systemically searched, and data on demographic, clinical, and biochemical characteristics and treatment outcomes were obtained.

Results

We reviewed seven patients among 60 McCune-Albright syndrome patients at Peking Union Medical College Hospital (5 female) and 39 patients (25 female) from the published literature. Six of the seven patients from Peking Union Medical College Hospital and half of the patients from the published studies were pediatric patients. These patients had increased growth velocity Z-scores and bone age over chronological age ratios. After good control of both conditions, the growth velocity Z-score and bone age over chronological age ratio decreased significantly, and the predicted adult height Z-score increased. The final heights and predicted adult height Z-scores were not impaired in patients with gigantism. All the patients had craniofacial fibrous dysplasia associated with optic and otologic complications.

Conclusion

McCune-Albright syndrome with growth hormone excess and precocious puberty is more common in girls. Patients have accelerated linear growth and advanced skeletal age, and early and good control of both conditions leads to a reduced growth velocity and stabilized bone age. The predicted adult and final heights are not negatively affected when growth hormone excess is diagnosed in pediatric patients.

Minimal models provide maximally parsimonious explanations

We are delighted that Diniz-Filho et al. agree with the main premise of our paper, and we welcome their critique, as constructive debate will help foster a better understanding of size evolution on islands. Our perspective on each of their criticisms is discussed in greater detail below.

Twenty-year follow-up of the facial phenotype of Brazilian patients with Sotos syndrome

Sotos syndrome is characterized by overgrowth starting before birth through childhood with intellectual disability and craniofacial anomalies. The majority of patients are large for gestational age with developmental delay or intellectual disability. The majority of cases are caused by pathogenic variants in NSD1. The most consistent physical features in this disorder are facial dysmorphisms including prominent forehead, downslanted palpebral fissures, prognathism with a pointed chin, and a long and narrow face. We present a follow-up to a cohort of 11 individuals found to harbor heterozygous, pathogenic, or likely pathogenic variants in NSD1. We analyzed the facial dysmorphisms and the condition using retrospective over 20 years. Among these patients, followed in our medical genetics outpatient clinic for variable periods of time, all had a phenotype compatible with the characteristic Sotos syndrome facial features, which evolved with time and became superimposed with natural aging modifications. We present here a long-term follow-up of facial features of Brazilian patients with molecularly confirmed Sotos syndrome. In this largest Brazilian cohort of molecularly confirmed patients with Sotos syndrome to date, we provide a careful description of the facial phenotype, which becomes less pronounced with aging and possibly more difficult to recognize in adults. These results may have broad clinical implications for diagnosis and add to the global clinical delineation of this condition.

An Update on Pituitary Neuroendocrine Tumors Leading to Acromegaly and Gigantism

An excess of growth hormone (GH) results in accelerated growth and in childhood, the clinical manifestation is gigantism. When GH excess has its onset after epiphyseal fusion at puberty, the overgrowth of soft tissue and bone results in acromegaly. Persistent GH excess in gigantism also causes acromegalic features that become evident in the adult years. The causes of GH excess are primarily lesions in the pituitary, which is the main source of GH. In this review, we provide an update on the clinical, radiological and pathologic features of the various types of pituitary neuroendocrine tumors (PitNETs) that produce GH. These tumors are all derived from PIT1-lineage cells. Those composed of somatotrophs may be densely granulated, resembling normal somatotrophs, or sparsely granulated with unusual fibrous bodies. Those composed of mammosomatotrophs also produce prolactin; rare plurihormonal tumors composed of cells that resemble mammosomatotrophs also produce TSH. Some PitNETs are composed of immature PIT1-lineage cells that do not resemble differentiated somatotrophs, mammosomatotrophs, lactotroph or thyrotrophs; these tumors may cause GH excess. An unusual oncocytic PIT1-lineage tumor known as the acidophil stem cell tumor is predominantly a lactotroph tumor but may express GH. Immature PIT1-lineage cells that express variable amounts of hormones alone or in combination can sometimes cause GH excess. Unusual tumors that do not follow normal lineage differentiation may also secrete GH. Exceptional examples of acromegaly/gigantism are caused by sellar tumors composed of hypothalamic GHRH-producing neurons, alone or associated with a sparsely granulated somatotroph tumor. Each of these various tumors has distinct clinical, biochemical and radiological features. Data from careful studies based on morphologic subtyping indicate that morphologic classification has both prognostic and predictive value.

A simple null model predicts the island rule

The island rule is a putative pattern in island evolution, where small species become larger on islands and large species become smaller. Despite decades of study, a mechanistic explanation for why some taxonomic groups obey the island rule, while others do not, has yet to be identified. Here, we explore whether the island rule might result from evolutionary drift. We derived a simulation model that predicts evolutionary size changes on islands based on random evolutionary trajectories along bounded trait domains. The model consistently predicted the island rule and could account for its occurrence in plants inhabiting islands in the Southwest Pacific. When support for the island rule was not detected, insular gigantism was often observed, suggesting that natural selection was at work. Overall results indicate that evolutionary drift can provide a parsimonious explanation for the island rule, suggesting future work should focus on circumstances where it does not occur.

Overgrowth in myth and art

Individuals with overgrowth have been the subjects of numerous myths and art pieces in various cultures, often depicted as deities or creatures of divine origin, such as giants or titans. In more recent times, however, subjects with signs of generalized or segmental overgrowth have been considered as "freaks of nature," in the disparaging language of the time, and represented in artworks as elements of entertainment or amusement. The different meanings assigned to overgrowth in myth and art through time provide an interesting perspective of the sociocultural approach to dysmorphic traits and genetic disorders.

How to Make a Rodent Giant: Genomic Basis and Tradeoffs of Gigantism in the Capybara, the World's Largest Rodent

Gigantism results when one lineage within a clade evolves extremely large body size relative to its small-bodied ancestors, a common phenomenon in animals. Theory predicts that the evolution of giants should be constrained by two tradeoffs. First, because body size is negatively correlated with population size, purifying selection is expected to be less efficient in species of large body size, leading to increased mutational load. Second, gigantism is achieved through generating a higher number of cells along with higher rates of cell proliferation, thus increasing the likelihood of cancer. To explore the genetic basis of gigantism in rodents and uncover genomic signatures of gigantism-related tradeoffs, we assembled a draft genome of the capybara (Hydrochoerus hydrochaeris), the world's largest living rodent. We found that the genome-wide ratio of nonsynonymous to synonymous mutations (ω) is elevated in the capybara relative to other rodents, likely caused by a generation-time effect and consistent with a nearly neutral model of molecular evolution. A genome-wide scan for adaptive protein evolution in the capybara highlighted several genes controlling postnatal bone growth regulation and musculoskeletal development, which are relevant to anatomical and developmental modifications for an increase in overall body size. Capybara-specific gene-family expansions included a putative novel anticancer adaptation that involves T-cell-mediated tumor suppression, offering a potential resolution to the increased cancer risk in this lineage. Our comparative genomic results uncovered the signature of an intragenomic conflict where the evolution of gigantism in the capybara involved selection on genes and pathways that are directly linked to cancer.

Pseudoacromegaly with acromegalic features in radiography

Pseudoacromegaly is a condition characterized by acromegalic physical features without growth hormone excess, for which radiographic observation has seldom been reported. This is a rare case of pseudoacromegaly.

Genetics of Acromegaly and Gigantism

Growth hormone (GH)-secreting pituitary tumours represent the most genetically determined pituitary tumour type. This is true both for germline and somatic mutations. Germline mutations occur in several known genes (AIP, PRKAR1A, GPR101, GNAS, MEN1, CDKN1B, SDHx, MAX) as well as familial cases with currently unknown genes, while somatic mutations in GNAS are present in up to 40% of tumours. If the disease starts before the fusion of the epiphysis, then accelerated growth and increased final height, or gigantism, can develop, where a genetic background can be identified in half of the cases. Hereditary GH-secreting pituitary adenoma (PA) can manifest as isolated tumours, familial isolated pituitary adenoma (FIPA) including cases with AIP mutations or GPR101 duplications (X-linked acrogigantism, XLAG) or can be a part of systemic diseases like multiple endocrine neoplasia type 1 or type 4, McCune-Albright syndrome, Carney complex or phaeochromocytoma/paraganglioma-pituitary adenoma association. Family history and a search for associated syndromic manifestations can help to draw attention to genetic causes; many of these are now tested as part of gene panels. Identifying genetic mutations allows appropriate screening of associated comorbidities as well as finding affected family members before the clinical manifestation of the disease. This review focuses on germline and somatic mutations predisposing to acromegaly and gigantism.

A Case of Luscan-Lumish Syndrome: Possible Involvement of Enhanced GH Signaling

CONTEXT

Luscan-Lumish syndrome (LLS) is characterized by postnatal overgrowth, obesity, Chiari I malformation, seizures, and intellectual disability. SET domain-containing protein 2 (SETD2) is a histone methyltransferase, where mutations in the gene are associated with the development of LLS. However, mechanisms underlying LLS remain unclear.

CASE DESCRIPTION

A 20-year-old man was referred to our hospital because of tall stature. His body height was 188.2 cm (+3.18 SD) and he showed obesity with a body mass index of 28.4 kg/m2. He exhibited acral overgrowth, jaw malocclusion, and prognathism, but no history of seizures, intellectual disability, or speech delay. Serum growth hormone (GH), insulin-like growth factor 1 (IGF-1), and nadir GH levels after administration of 75 g oral glucose were within normal range. Pituitary magnetic resonance imaging showed no pituitary adenoma, but Chiari I malformation. Whole exome sequencing analysis of the proband revealed a de novo heterozygous germline mutation in SETD2 (c.236T>A, p.L79H). Skin fibroblasts derived from the patient grew faster than those from his father and the control subject. In addition, these cells showed enhanced tyrosine phosphorylation and transcriptional activity of signal transducer and activator of transcription 5b (STAT5b) and increased IGF-1 expression induced by GH.

CONCLUSION

This is a mild case of LLS with a novel mutation in SETD2 without neurological symptoms. LLS should be differentiated in a patient with gigantism without pituitary tumors. Although further investigation is necessary, this is the first study to suggest the involvement of aberrant GH signaling in the development of LLS.

Shrinking body sizes in response to warming: explanations for the temperature-size rule with special emphasis on the role of oxygen

Body size is central to ecology at levels ranging from organismal fecundity to the functioning of communities and ecosystems. Understanding temperature-induced variations in body size is therefore of fundamental and applied interest, yet thermal responses of body size remain poorly understood. Temperature-size (T-S) responses tend to be negative (e.g. smaller body size at maturity when reared under warmer conditions), which has been termed the temperature-size rule (TSR). Explanations emphasize either physiological mechanisms (e.g. limitation of oxygen or other resources and temperature-dependent resource allocation) or the adaptive value of either a large body size (e.g. to increase fecundity) or a short development time (e.g. in response to increased mortality in warm conditions). Oxygen limitation could act as a proximate factor, but we suggest it more likely constitutes a selective pressure to reduce body size in the warm: risks of oxygen limitation will be reduced as a consequence of evolution eliminating genotypes more prone to oxygen limitation. Thus, T-S responses can be explained by the 'Ghost of Oxygen-limitation Past', whereby the resulting (evolved) T-S responses safeguard sufficient oxygen provisioning under warmer conditions, reflecting the balance between oxygen supply and demands experienced by ancestors. T-S responses vary considerably across species, but some of this variation is predictable. Body-size reductions with warming are stronger in aquatic taxa than in terrestrial taxa. We discuss whether larger aquatic taxa may especially face greater risks of oxygen limitation as they grow, which may be manifested at the cellular level, the level of the gills and the whole-organism level. In contrast to aquatic species, terrestrial ectotherms may be less prone to oxygen limitation and prioritize early maturity over large size, likely because overwintering is more challenging, with concomitant stronger end-of season time constraints. Mechanisms related to time constraints and oxygen limitation are not mutually exclusive explanations for the TSR. Rather, these and other mechanisms may operate in tandem. But their relative importance may vary depending on the ecology and physiology of the species in question, explaining not only the general tendency of negative T-S responses but also variation in T-S responses among animals differing in mode of respiration (e.g. water breathers versus air breathers), genome size, voltinism and thermally associated behaviour (e.g. heliotherms).

A Case of Simpson-Golabi-Behmel Syndrome Presenting with Cutaneous Findings

Description Simpson-Golabi-Behmel syndrome is a rare, X-linked recessive syndrome associated with mutations in the genes encoding glypican 3 (GPC3). The majority of cases have been described in pediatric males, with those affected showing manifestations of overgrowth, congenital heart defects, and increased incidence of neoplasia. Due to the X-linked nature of this disorder, penetrance is not well understood in female cases. Very few cases of female presentations of Simpson-Golabi-Behmel syndrome have been described, and this case highlights that there may be an association between mutated GPC3 carrier status and other cancers. We present a case of GPC3 gene mutation suggestive of Simpson-Golabi-Behmel syndrome in an adult female patient, diagnosed based on genetic testing performed due to a diagnosis of sebaceous carcinoma.

Osteohistological analyses reveal diverse strategies of theropod dinosaur body-size evolution

The independent evolution of gigantism among dinosaurs has been a topic of long-standing interest, but it remains unclear if gigantic theropods, the largest bipeds in the fossil record, all achieved massive sizes in the same manner, or through different strategies. We perform multi-element histological analyses on a phylogenetically broad dataset sampled from eight theropod families, with a focus on gigantic tyrannosaurids and carcharodontosaurids, to reconstruct the growth strategies of these lineages and test if particular bones consistently preserve the most complete growth record. We find that in skeletally mature gigantic theropods, weight-bearing bones consistently preserve extensive growth records, whereas non-weight-bearing bones are remodelled and less useful for growth reconstruction, contrary to the pattern observed in smaller theropods and some other dinosaur clades. We find a heterochronic pattern of growth fitting an acceleration model in tyrannosaurids, with allosauroid carcharodontosaurids better fitting a model of hypermorphosis. These divergent growth patterns appear phylogenetically constrained, representing extreme versions of the growth patterns present in smaller coelurosaurs and allosauroids, respectively. This provides the first evidence of a lack of strong mechanistic or physiological constraints on size evolution in the largest bipeds in the fossil record and evidence of one of the longest-living individual dinosaurs ever documented.

Etiology and Clinical Profile of Patients with Tall Stature: A Single-Center Experience

BACKGROUND

There is no published literature on the profile of patients with tall stature (TS) from India. This study aimed to evaluate the etiological and clinical profile of patients with TS referred to our hospital.

MATERIALS AND METHODS

We performed a retrospective review of records of patients referred to us for evaluation of TS (January 2007 to March 2020). Relevant clinical, anthropometric, biochemical, and radiological data at presentation were recorded, and the final diagnosis reviewed.

RESULTS

The study included 16 subjects (6 boys, 10 girls) with a mean age at presentation of 13.2 ± 3.6 years. Most subjects were pubertal (n = 10) and belonged to the overweight or obese category (n = 10). The mean height and height standard deviation score (SDS) were 172.3 ± 20.3 cm and 3.6 ± 1.5, respectively, while mean mid-parental height (MPH) and MPH SDS were 168.8 ± 8.8 cm and 1.2 ± 0.9, respectively. The etiological diagnoses were familial TS (n = 9), acrogigantism (n = 3), obesity-related TS (n = 2), constitutional advancement of growth (n = 1), and Marfan syndrome (n = 1). The mean height SDS in subjects with acrogigantism was 6.4 ± 1.2 compared to 3.0 ± 0.6 in those with other etiologies of TS. Only one girl with familial TS and significantly increased predicted adult height (+4.56 SDS) opted for sex steroid therapy.

CONCLUSION

Familial TS is the most common diagnosis among patients referred for evaluation to our hospital. One should consider the possibility of acrogigantism in patients with growth acceleration, extreme TS, and markedly increased gap between height SDS and MPH SDS. Most patients with familial TS require reassurance and sex steroid therapy should be reserved for highly selected cases.

Phenotypic and genotypic features of a large kindred with a germline AIP variant

CONTEXT

Acromegaly is usually a sporadic disease, but familial cases occur. Mutations in the aryl hydrocarbon receptor-interacting protein (AIP) gene are associated with familial pituitary adenoma predisposition. However, the pathogenicity of some AIP variants remains unclear and additional unknown genes may be involved.

OBJECTIVE

To explore the phenotype and genotype of a large kindred carrying the p.R304Q AIP variant.

METHODS

The family comprised 52 family members at risk of carrying the p.R304Q AIP variant including a case with gigantism and one with acromegaly and several family members with acromegalic features. Nine family members (three trios) underwent exome sequencing to identify putative pathogenic variants.

RESULTS

We identified 31 p.R304Q carriers, and based on two cases with somatotropinomas, the disease penetrance was 6%. We observed physical signs of acromegaly in several family members, which were independent of AIP status. Serum insulin-like growth factor-I (IGF-I) levels in all family members were above the mean for age and sex (IGF-I SDS: +0.6 [CI95% +0.4-0.9], P < .01). Exome analysis identified two candidate genes: PDE11A, known to be associated with the development of adrenal tumours, and ALG14. Ten asymptomatic p.R304Q family members (age >50 years) were screened for the PDE11A and ALG14 variant; both variants were present in five of ten persons.

CONCLUSIONS

This large family adds new information on the p.R304Q AIP variant, and data suggest two new candidate genes could be associated with growth hormone excess.

HEREDITARY ENDOCRINE TUMOURS: CURRENT STATE-OF-THE-ART AND RESEARCH OPPORTUNITIES: GPR101, an orphan GPCR with roles in growth and pituitary tumorigenesis

We recently described X-linked acrogigantism (X-LAG) in sporadic cases of infantile gigantism and a few familial cases of pituitary gigantism in the context of the disorder known as familial isolated pituitary adenomas. X-LAG cases with early onset gigantism (in infants or toddlers) shared copy number gains (CNG) of the distal long arm of chromosome X (Xq26.3). In all patients described to date with Xq26.3 CNG and acro-gigantism, the only coding gene sequence shared by all chromosomal defects was that of GPR101. GPR101 is a class A, rhodopsin-like orphan guanine nucleotide-binding protein (G protein)-coupled receptor (GPCR) with no known endogenous ligand. We review what is known about GPR101, specifically its expression profile in human and animal models, the evidence supporting causation of X-LAG and possibly other roles, including its function in growth, puberty and appetite regulation, as well as efforts to identify putative ligands.

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.

Potential markers of disease behavior in acromegaly and gigantism

Introduction: Acromegaly and gigantism entail increased morbidity and mortality if left untreated, due to the systemic effects of chronic GH and IGF-1 excess. Guidelines for the diagnosis and treatment of patients with GH excess are well established; however, the presentation, clinical behavior and response to treatment greatly vary among patients. Numerous markers of disease behavior are routinely used in medical practice, but additional biomarkers have been recently identified as a result of basic and clinical research studies.Areas covered: This review focuses on genetic, molecular and genomic features of patients with GH excess that have recently been linked to disease progression and response to treatment. A PubMed search was conducted to identify markers of disease behavior in acromegaly and gigantism. Markers already considered as part of routine studies in clinical care guidelines were excluded. Literature search was expanded for each marker identified. Novel markers not included or only partially covered in previously published reviews on the subject were prioritized.Expert opinion: Recognizing the most relevant markers of disease behavior may help the medical team tailoring the strategies for approaching each case of acromegaly and gigantism. This customized plan should make the evaluation, treatment and follow up process more efficient, greatly improving the patients' outcomes.

Pituitary gigantism: a rare learning opportunity

INTRODUCTION

Pituitary gigantism is a rare but significant paediatric condition with complexities surrounding diagnosis and management. Transsphenoidal surgery (TSS) is the treatment of choice; however, medical treatment is often considered as adjuvant therapy.

CASE

A 10½ -year-old boy presented with tall stature and a height velocity of 11 cm/year. His height was 178.7 cm (+5.8 SD above mean) and insulin-like growth factor-1 (IGF-1) was elevated. An oral glucose tolerance test demonstrated non-suppression of growth hormone (GH). Initial contrast MRI was inconclusive, but C-11 methionine functional positron emission tomography CT identified a 6 mm pituitary microadenoma. A multidisciplinary team clinic held with the family allowed discussion about medical and surgical treatment options. Due to a number of factors including the patient's young age, prepubertal status, a wish to allow him to settle into his new high school and his desire to reach a final height taller than his father's height, it was decided to try medical therapy first with a somatostatin analogue. Pubertal induction was also commenced and bilateral epiphysiodesis surgery performed. Initial response to octreotide was positive; however, 4 months into therapy his IGF-1 was climbing and a repeat GH profile was not fully suppressed. The patient therefore proceeded to have successful TSS excision of the adenoma.

CONCLUSION

Rare cases such as this require sharing of knowledge and expertise, so the best possible care is offered. It is often necessary to work across sites and disciplines. Each case requires an individual approach tailored to the patient and their family.

Enhanced recruitment of larger predators in the presence of large prey

Most carnivores undergo diet shift from smaller to larger prey items during ontogeny. The trophic relationship between a growing carnivore and larger prey is representative of a size-structured predator-prey interaction. The strength of this interaction is, in part, determined by the recruitment of individuals from smaller predatory size classes into larger predatory size classes. Therefore, it is interesting to investigate how larger prey alter the recruitment of smaller predator size classes into larger predator size classes, since this can affect their own future predation risk. Past empirical studies have exclusively documented that large prey reduce predator recruitment by decreasing growth and/or survival of the smaller predators. In this study, we provide empirical evidence of the contrasting pattern: large prey enhance the recruitment of smaller predators into larger predators even though they increase cannibalism mortality of the smaller predators. We have done this here by studying the trophic interaction between predatory salamander larvae Hynobius retardatus and the frog tadpoles Rana pirica that represent their large prey. In a field experiment in which salamander hatchlings were exposed to the presence or absence of large frog tadpoles, we found that more giant salamanders emerged in the presence of frog tadpoles than in their absence. Reassignment of frog tadpoles (to both treatments) in the subsequent experimental period showed that the enhanced emergence of giant salamanders in the presence of frog tadpoles leads to the intensification of salamander predation on the frog tadpoles. In an additional laboratory experiment, to better understand the underlying mechanisms, we manipulated both the presence of frog tadpoles and the occurrence of cannibalism between salamander hatchlings. This experiment revealed that frog tadpoles intensify the cannibalism of salamander larvae during their hatchling stage, thus allowing more salamander larvae to become large-sized predators. Our results suggest that frog tadpoles can inadvertently intensify their own future predation risk by intensifying cannibalistic interactions among predatory salamander hatchlings, thereby enhancing the degree of predator recruitment to a larger size class. Hence, large prey can enhance the recruitment of individuals from small predator size classes into larger predator size classes.

Sexual Size Dimorphism: Evolution and Perils of Extreme Phenotypes in Spiders

Sexual size dimorphism is one of the most striking animal traits, and among terrestrial animals, it is most extreme in certain spider lineages. The most extreme sexual size dimorphism (eSSD) is female biased. eSSD itself is probably an epiphenomenon of gendered evolutionary drivers whose strengths and directions are diverse. We demonstrate that eSSD spider clades are aberrant by sampling randomly across all spiders to establish overall averages for female (6.9 mm) and male (5.6 mm) size. At least 16 spider eSSD clades exist. We explore why the literature does not converge on an overall explanation for eSSD and propose an equilibrium model featuring clade- and context-specific drivers of gender size variation. eSSD affects other traits such as sexual cannibalism, genital damage, emasculation, and monogyny with terminal investment. Coevolution with these extreme sexual phenotypes is termed eSSD mating syndrome. Finally, as costs of female gigantism increase with size, eSSD may represent an evolutionary dead end.

Too hip for two sacral vertebrae

A complex pelvic morphology has been discovered in the fossils of one of the largest crocodylians.

Giant extinct caiman breaks constraint on the axial skeleton of extant crocodylians

The number of precaudal vertebrae in all extant crocodylians is remarkably conservative, with nine cervicals, 15 dorsals and two sacrals, a pattern present also in their closest extinct relatives. The consistent vertebral count indicates a tight control of axial patterning by Hox genes during development. Here we report on a deviation from this pattern based on an associated skeleton of the giant caimanine Purussaurus, a member of crown Crocodylia, and several other specimens from the Neogene of the northern neotropics. P. mirandai is the first crown-crocodylian to have three sacrals, two true sacral vertebrae and one non-pathological and functional dorsosacral, to articulate with the ilium (pelvis). The giant body size of this caiman relates to locomotory and postural changes. The iliosacral configuration, a more vertically oriented pectoral girdle, and low torsion of the femoral head relative to the condyles are hypothesized specializations for more upright limb orientation or weight support.

The genetics of morphological and behavioural island traits in deer mice

Animals on islands often exhibit dramatic differences in morphology and behaviour compared with mainland individuals, a phenomenon known as the 'island syndrome'. These differences are thought to be adaptations to island environments, but the extent to which they have a genetic basis or instead represent plastic responses to environmental extremes is often unknown. Here, we revisit a classic case of island syndrome in deer mice (Peromyscus maniculatus) from British Columbia. We first show that Saturna Island mice and those from neighbouring islands are approximately 35% (approx. 5 g) heavier than mainland mice and diverged approximately 10 000 years ago. We then establish laboratory colonies and find that Saturna Island mice are heavier both because they are longer and have disproportionately more lean mass. These trait differences are maintained in second-generation captive-born mice raised in a common environment. In addition, island-mainland hybrids reveal a maternal genetic effect on body weight. Using behavioural testing in the laboratory, we also find that wild-caught island mice are less aggressive than mainland mice; however, laboratory-raised mice born to these founders do not differ in aggression. Together, our results reveal that these mice have different responses to the environmental conditions on islands-a heritable change in a morphological trait and a plastic response in a behavioural trait.

Pituitary gigantism: a case series from Hospital de San José (Bogotá, Colombia)

INTRODUCTION

Gigantism is a rare pediatric disease characterized by increased production of growth hormone (GH) before epiphyseal closure, that manifests clinically as tall stature, musculoskeletal abnormalities, and multiple comorbidities.

MATERIALS AND METHODS

Case series of 6 male patients with gigantism evaluated at the Endocrinology Service of Hospital de San José (Bogotá, Colombia) between 2010 and 2016.

RESULTS

All patients had macroadenomas and their mean final height was 2.01 m. The mean age at diagnosis was 16 years, and the most common symptoms were headache (66%) and hyperhidrosis (66%). All patients had acral changes, and one had visual impairment secondary to compression of the optic chiasm. All patients underwent surgery, and 5 (83%) required additional therapy for biochemical control, including radiotherapy (n = 4, 66%), somatostatin analogues (n = 5, 83%), cabergoline (n = 3, 50%), and pegvisomant (n = 2, 33%). Three patients (50%) achieved complete biochemical control, while 2 patients showed IGF-1 normalization with pegvisomant. Two patients were genetically related and presented a mutation in the aryl hydrocarbon receptor-interacting protein (AIP) gene (pathogenic variant, c.504G>A in exon 4, p.Trp168*), fulfilling the diagnostic criteria of familial isolated pituitary adenoma.

CONCLUSIONS

This is the largest case series of patients with gigantism described to date in Colombia. Transsphenoidal surgery was the first-choice procedure, but additional pharmacological therapy was usually required. Mutations in the AIP gene should be considered in familial cases of GH-producing adenomas.