Diagnosis and management of pseudohypoparathyroidism and related disorders: first international Consensus Statement

High Prevalence of Hypercalcitoninemia in a Large Cohort of Adult and Pediatric Patients With PTH Resistance Syndromes

CONTEXT

Pseudohypoparathyroidism (PHP) refers to a group of rare hereditary disorders associated with resistance to parathyroid hormone (PTH) and other hormones now termed inactivating PTH/PTHrP disorders (iPPSD). Hypercalcitoninemia has been seldom reported in small series.

OBJECTIVE

Our aim was to investigate the characteristics of hypercalcitoninemia in pediatric and adult patients with PHP/iPPSD.

METHODS

We retrospectively collected data from 2 cohorts from 2 European endocrinology tertiary centers: the pediatric cohort comprised 88 children with available calcitonin (CT) measurements; the adult cohort included 43 individuals with simultaneous CT and PTH measurements.

RESULTS

In the pediatric cohort, 65.9% had hypercalcitoninemia (median CT 15 ng/L); in the adult cohort 53.5% (mean CT 21.6 ng/L). There was no difference between CT in pediatric and adult population; we observed stable CT levels over a median follow-up of 134.5 months in adults. Notably, no correlations were detected between CT and PTH levels. Other etiologies of hypercalcitoninemia were excluded; adult patients underwent regular thyroid ultrasound to screen for medullary thyroid cancer (MTC). We performed 20 calcium stimulation tests in adult patients. While there was a significant difference in basal and peak CT between our patients, healthy subjects, and subjects with MTC, there was no difference with patients with C-cell hyperplasia.

CONCLUSION

This study underscores the common occurrence of hypercalcitoninemia in both pediatric and adult patients with PHP/iPPSD, in particular with subtypes iPPSD2 and iPPSD3. Furthermore, these patients show hyperresponsiveness to calcium stimulation tests falling between healthy subjects and patients with MTC. These findings contribute to the understanding of CT dynamics in the context of PHP/iPPSD.

Atypical presentation of pseudohypoparathyroidism with absence of mutations in the GNAS gene: a case report

BACKGROUND

This case report aimed to broaden the understanding of pseudohypoparathyroidism (PHP) manifestations when typical mutations in the GNAS gene are absent. The clinical, biochemical, and genetic investigations of a PHP case revealed diagnostic challenges and emphasized the importance of comprehensive genetic analysis for early diagnosis and appropriate management, as well as improved patient outcomes.

CASE PRESENTATION

The case involved a 21-year-old man who has experienced recurrent limb convulsions and episodes of altered consciousness since the age of eight. Recent assessments during frequent hospitalization uncovered findings consistent with PHP, including hypocalcemia, hyperphosphatemia, elevated parathyroid hormone level, and short stature. Notably, genetic testing did not reveal mutations in the GNAS gene, which could be typically associated with PHP. Diagnostic tests revealed mild abnormalities in the electroencephalogram and multiple abnormal signals in brain magnetic resonance imaging, specifically in the caudate, lenticular, dentate, and thalamus nuclei. Cranial computed tomography scan confirmed symmetrical calcifications in the basal ganglia. Biochemical analysis revealed severely altered calcium and phosphorus metabolism. Routine endocrine and neurological evaluations yielded results within normal ranges. Genetic testing identified a novel missense mutation in the GHSR gene, which has not been reported in the database and may reasonably explain some of the patient's phenotypic features.

CONCLUSIONS

While mutations in the GNAS gene are the primary genetic markers for PHP, the presence of other genetic mutations in some cases complicates the clinical analysis. This case highlights the need for a comprehensive genetic screening approach in patients with PHP-like symptoms who do not exhibit mutations in the GNAS gene, to avoid misdiagnosis and ensure timely intervention.

CLINICAL TRIAL NUMBER

Not applicable.

Hypocalcemic Tetany Transiently "Cured" by Pregnancy: A Case Report

Hypocalcemia is an uncommon electrolyte abnormality. We evaluated a young woman with episodes of recurrent symptomatic hypocalcemia which had started in her late teens. She was hypertensive and laboratory evaluation revealed an elevated PTH, elevated phosphate, and decreased renal phosphate excretion along with low ionized calcium levels. Her renin and aldosterone levels were elevated. While the response to treatment with calcium and 1,25 vitamin D was modest, her laboratory values and symptoms improved significantly during pregnancy and then recurred post-delivery. Based on clinical and laboratory features, we made a diagnosis of pseudohypoparathyroidism type Ib (PHP1B). Her genomic DNA revealed broad methylation changes at the GNAS locus which encodes the alpha-subunit of the stimulatory G protein (Gαs) without evidence for a deletion or duplication, consistent with PHP1B. Analyses of several microsatellite markers on chromosome 20 performed on our patient and her parents provided no evidence for paternal uniparental isodisomy/heterodisomy of chromosome 20q13.3 (patUPD20q). The approach to hypocalcemia; classification, clinical features, and genetic/epigenetic basis for pseudohypoparathyroidism; alterations of mineral metabolism in PHP1B and pregnancy; and implications for the high renin and aldosterone levels and hypokalemia are discussed.

Skipping of Exon 20 in EP300: A Novel Variant Linked to Rubinstein-Taybi Syndrome With Atypical and Severe Clinical Manifestations

Rubinstein-Taybi syndrome (RSTS) is a rare autosomal dominant neurodevelopmental disorder linked to haploinsufficiency of CREBBP (RSTS1) and EP300 (RSTS2) genes. Characteristic features often include distinctive facial traits, broad thumbs and toes, short stature, and various degrees of intellectual disability. The clinical presentation of RSTS is notably variable, making it challenging to establish a clear genotype-phenotype correlation, except for specific variants which cause the allelic Menke-Hennekam syndrome. Trio exome analysis, data collection via networking and GeneMatcher platforms, transcript processing analysis, and DNA methylation profiling were performed. We identified two unrelated patients with de novo variants in EP300 (NM_001429.4: c.3671+5G>C; c.3671+5_3671+8delGTAA) predicted to cause in-frame exon 20 skipping, confirmed in one patient. In silico 3D protein modeling suggested that exon 20 deletion (comprising 27 amino acids) likely alters the structural conformation between the RING_CBP-p300 and HAT-KAT11 domains. Clinically, both patients displayed severe RSTS2-like clinical features, including autism spectrum disorder, speech delay, hearing loss, microcephaly, developmental delay, and intellectual disability, alongside ocular, respiratory, and cardiovascular abnormalities. Additionally, one patient developed early-onset colorectal cancer. DNA methylation profiling in Subject #1 confirmed RSTS but did not align with the specific episignatures for RSTS1 or RSTS2. We propose that skipping of exon 20 in EP300 is associated with a distinct form of Rubinstein-Taybi syndrome featuring clinical characteristics not fully aligning with RSTS1 or RSTS2. Our findings increase the understanding of RSTS genetic and molecular basis and stress the need for further research to establish definitive genotype-phenotype correlations.

Management of Adolescent Obesity

This article provides a contemporary review of adolescent obesity management, focusing on the importance of a comprehensive and multidisciplinary approach. It highlights the necessity of integrating lifestyle/behavioral modifications, pharmacologic interventions, and surgical options where applicable, tailored to the individual needs of adolescents to effectively combat obesity and its associated risks.

Pediatric hypoparathyroidism: etiological and clinical evaluation in a tertiary center

PURPOSE

This study aims to evaluate the etiology, clinical presentation, and management of pediatric hypoparathyroidism in a tertiary center.

METHODS

A retrospective review was conducted on pediatric patients diagnosed with hypoparathyroidism at the Pediatric Endocrinology Clinic from March 2021 to June 2023. Data on demographic characteristics, presenting symptoms, laboratory findings, genetic analyses, and treatment outcomes were collected.

RESULTS

A total of 56 patients (31 females) were included. The median age at diagnosis of the patients was 5.5 years (range 0.04-17 years), and the median age of symptom onset was 5 years (range 0.04-16.5 years). The etiology was genetic and idiopathic in 39 patients (70.9%), with syndromic forms, familial isolated hypoparathyroidism, and hypomagnesemia identified. DiGeorge syndrome was present in 14 patients, making it the most common syndromic form. The syndromes associated with hypomagnesemia were those with mutations in the TRMP6 and CLDN16 genes. Sixteen patients (29.1%) had acquired causes, primarily post-thyroid surgery and autoimmune conditions. Common symptoms included muscle spasms (32.7%) and seizures (21.8%). Laboratory findings revealed a median serum calcium level of 6.7 mg/dL (3.8-8.5) and median serum phosphorus level of 7.7 (4.9-12.5) mg/dL. Treatment primarily involved calcitriol [The median dose of calcitriol is 25 ng/kg/day (range: 25-50 ng/kg/day)] and calcium [The median dose of calcium gluconate is 0.7 mL/kg (range: 0.5-1 mL/kg) and oral calcium is 1000 mg (range: 700-1300 mg)] supplementation. Intravenous calcium gluconate treatment was administered to 39 (70.6%) patients, oral calcium carbonate therapy was given to 16 (29.1%) patients, and calcitriol treatment was initiated for 51 (91.1%) patients. Complications such as nephrocalcinosis (7, 13.7%) and hypercalciuria (7, 13.7%) were observed in some patients.

CONCLUSION

This study emphasizes the significant genetic component, particularly syndromic, in pediatric hypoparathyroidism, highlighting the need for comprehensive genetic evaluation and a multidisciplinary approach for effective management, especially concerning complications. In this way, early and accurate diagnosis will reduce unnecessary tests, treatment approaches, and repeated hospital visits. Regular monitoring is essential to mitigate potential complications associated with long-term treatment.

Obesity with developmental delay in infancy: a rare cause not to miss-pseudohypoparathyroidism

Mild developmental delay in infants with obesity is often disregarded, attributing it to increased weight by parents and practitioners. We report an infant with obesity and gross motor delay after the first 6 months of age, seizures and obstructive sleep apnoea. The child was diagnosed with pseudohypoparathyroidism (PHP) and was medically managed with parenteral calcium, vitamin D and magnesium. Appropriate early interventions by developmental therapists addressing the developmental domains coordinated by developmental paediatricians and relevant drug and diet management corrected the delay. The child is followed up for soft tissue calcifications, kidney functions and skeletal health. This case highlights the importance of early recognition and comprehensive management of correctable conditions like PHP by developmental specialists rather than addressing only the developmental aspect of it.

A biallelically active embryonic enhancer dictates GNAS imprinting through allele-specific conformations

Genomic imprinting controls parental allele-specific gene expression via epigenetic mechanisms. Abnormal imprinting at the GNAS gene causes multiple phenotypes, including pseudohypoparathyroidism type-1B (PHP1B), a disorder of multihormone resistance. Microdeletions affecting the neighboring STX16 gene ablate an imprinting control region (STX16-ICR) of GNAS and lead to PHP1B upon maternal but not paternal inheritance. Mechanisms behind this imprinted inheritance mode remain unknown. Here, we show that the STX16-ICR forms different chromatin conformations with each GNAS parental allele and enhances two GNAS promoters in human embryonic stem cells. When these cells differentiate toward proximal renal tubule cells, STX16-ICR loses its effect, accompanied by a transition to a somatic cell-specific GNAS imprinting status. The activity of STX16-ICR depends on an OCT4 motif, whose disruption impacts transcript levels differentially on each allele. Therefore, a biallelically active embryonic enhancer dictates GNAS imprinting via different chromatin conformations, underlying the allele-specific pathogenicity of STX16-ICR microdeletions.

Pseudohypoparathyroidism: Challenges in Early Recognition and Diagnosis of a Rare Hereditary Disorder

Pseudohypoparathyroidism (PHP) is an uncommon endocrine condition marked by an impaired response to parathyroid hormone (PTH), which results in biochemical abnormalities. Clinical manifestations can vary significantly, occasionally resembling other endocrine disorders. Genetic testing plays a critical role in distinguishing PHP from other conditions, as it enables precise diagnosis even when classical features are not initially present. We report the case of a male infant initially diagnosed with congenital hypothyroidism (CH) through neonatal screening and treated with levothyroxine. While growing up, the patient developed syndromic features, including facial dysmorphisms, global developmental delay, behavioural issues, and early-onset obesity. Whole exome sequencing (WES), prompted by the complex phenotype, identified a maternally inherited GNAS variant. This led to the suspicion of PHP1A, which was subsequently confirmed at five years of age when laboratory reevaluation revealed hypocalcemia, hyperphosphatemia, and elevated PTH levels. PHP can mimic isolated CH in early presentations, often delaying recognition. This case underscores the pivotal role of genetic testing in diagnosing PHP. Early genetic evaluation and multidisciplinary care are essential for accurate diagnosis, tailored treatment, and long-term monitoring, ultimately improving patient outcomes.

Chapter 4: Differential diagnosis of primary hyperparathyroidism

The differential diagnosis of primary hyperparathyroidism can be considered clinically, biologically and radiologically. Clinically, primary hyperparathyroidism should be suspected in case of diffuse pain, renal lithiasis, osteoporosis, repeated fracture, cognitive or psychiatric disorder, or disturbance of consciousness. Nevertheless, the differential diagnosis of primary hyperparathyroidism is mainly biological, particularly in atypical forms, which must be differentiated from hypercalcemia with hypocalciuria or non-elevated PTH on the one hand, and from normo-calcemia with elevated PTH, hypophosphatemia or hypercalciuria on the other. Any differential diagnosis must be preceded by an analysis of the factors likely to disturb phospho-calcium parameters: vitamin D deficiency (assay), renal insufficiency (eGFR measurement), malabsorption (inflammatory disease of the digestive tract, celiac disease, bariatric surgery, etc.), insufficient calcium intake (GRIO questionnaire) and iatrogenic causes (diuretics, anti-osteoporotic drugs, excessive vitamin D or calcium supplementation, lithium, corticosteroid therapy, phosphorus intake). Once these factors have been eliminated, hypercalcemia with hypocalciuria should suggest a genetic cause. Hypercalcemia with non-elevated PTH may be secondary to neoplasm, hypervitaminosis D (excessive intake, production or catabolism), immobilization or endocrine causes. Elevated PTH values without hypercalcemia must be differentiated from normo-calcemic hyperparathyroidism. High PTH levels are found in PTH-resistant patients, as well as in hypophosphatemic (especially X-linked) or hypercalciuric tubulopathies (certain rare diseases, immobilization, loop diuretics or idiopathic causes favored by a metabolic syndrome). Radiologically, brown tumor must be differentiated primarily from bone metastasis, chondrosarcoma and giant cell tumor.

Pseudohypoparathyroidism Type 1b with Digital Clubbing

Pseudohypoparathyroidism (PHP) is a rare disorder characterized by resistance to parathyroid hormone (PTH). Albright's hereditary osteodystrophy (AHO) is a characteristic physical condition associated with PHP. We herein report a 33-year-old Japanese man diagnosed with PHP type 1b who presented with hypocalcemia, preserved PTH secretion, decreased urinary cAMP and phosphate excretion (Ellsworth-Howard test), deletion of exons 5-7 in STX16, hypomethylation of A/B-DMR and AS1-DMR in the guanine nucleotide binding protein alpha stimulating gene. The patient did not have AHO or other comorbidities but showed digital clubbing during childhood. Although digital clubbing is rarely associated with PHP, it may represent a phenotype of this disorder.

Pseudohypoparathyroidism type 1A presenting as short stature and congenital hypothyroidism

Summary

Short stature is a common complaint among pediatric visits and the differential diagnosis is extensive. Although some variations in growth are normal, deviation from normal growth is often the first symptom of chronic disease in children. This is true for hormone abnormalities including growth hormone deficiency, hypothyroidism and glucocorticoid excess. However, reduced growth velocity can also occur as the first sign of chronic anemia, malnutrition, deprivation (psychosocial dwarfism), chromosomal abnormalities, genetic syndromes and inflammatory bowel diseases. For the primary care provider, simple measures of standing height, sitting height, arm span, weight, body mass index (BMI) and bone age (BA) will lead to the correct diagnosis in most short children. Screening laboratory studies for endocrine disorders, a skeletal survey if skeletal disproportion is evident, a karyotype or microarray (microarray favored if developmental delay is also present) and genetic testing for monogenic disorders will lead to a specific diagnosis in an additional subset of short children. This case presented a diagnostic dilemma that spanned all these possibilities and served as a focal point for the review of normal growth and growth abnormalities.

Learning points

Variations in growth can be normal variants (constitutional delay of growth and puberty or familial short stature) but deviation from normal growth can also be the first sign of an underlying pathological process. Measures of standing height, sitting height, arm span, weight, body mass index (BMI) and bone age (BA) will lead to the correct diagnosis in 50-80% of short children. Screening laboratory studies for endocrine disorders, a skeletal survey if skeletal disproportion is evident, a karyotype or microarray (microarray is favored if developmental delay is also present) and genetic testing will lead to a specific diagnosis in another 35% of short children. Pseudohypoparathyroidism (PHP) type 1A is due to a mutation in the alpha subunit of the stimulatory G protein of the guanine nucleotide-binding protein gene. Multiple hormone resistance often affects thyroid-stimulating hormone and, when presenting in the newborn period, can be misdiagnosed as common forms of congenital hypothyroidism. Molecular testing is an important component of confirming the diagnosis and PHP subtype, which can help guide management.

Recurrent small variants in NESP55/NESPAS associated with broad GNAS methylation defects and pseudohypoparathyroidism type 1B

Pseudohypoparathyroidism type 1B (PHP1B) is associated with epigenetic changes in the maternal allele of the imprinted GNAS gene that inhibit expression of the α subunit of Gs (Gsα), thereby leading to parathyroid hormone resistance in renal proximal tubule cells where expression of Gsα from the paternal GNAS allele is normally silent. Although all patients with PHP1B show loss of methylation for the exon A/B differentially methylated region (DMR), some patients with autosomal dominant PHP1B (AD-PHP1B) and most patients with sporadic PHP1B have additional methylation defects that affect the DMRs corresponding to exons XL, AS1, and NESP. Because the genetic defect is unknown in most of these patients, we sought to identify the underlying genetic basis for AD-PHP1B in 2 multigenerational families with broad GNAS methylation defects and negative clinical exomes. Genome sequencing identified small GNAS variants in each family that were also present in unrelated individuals with PHP1B in a replication cohort. Maternal transmission of one GNAS microdeletion showed reduced penetrance in some unaffected patients. Expression of AS transcripts was increased, and NESP was decreased, in cells from affected patients. These results suggest that the small deletion activated AS transcription, leading to methylation of the NESP DMR with consequent inhibition of NESP transcription, and thereby provide a potential mechanism for PHP1B.

Heterodisomy in the GNAS locus is also a cause of pseudohypoparathyroidism type 1B (iPPSD3)

Objective

To identify the genetic cause underlying the methylation defect in a patient with clinical suspicion of PHP1B/iPPSD3.

Design

Imprinting is an epigenetic mechanism that allows the regulation of gene expression. The GNAS locus is one of the loci within the genome that is imprinted. When the methylation pattern is affected, it causes pseudohypoparathyroidism type 1B (PHP1B) or inactivating PTH/PTHrP signaling disorder 3 (iPPSD3). Paternal uniparental isodisomy (iUPDpat) of the chromosomal region comprising the GNAS locus has been described as one of the possible underlying genetic causes of the methylation alteration.

Methods

We present the case of a patient clinically diagnosed with iPPSD3. We performed a commercial methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA), single-nucleotide polymorphism (SNP) array, and microsatellite study. In addition, we designed a custom MS-MLPA to analyze GNAS and nearby differentially methylated regions (DMRs).

Results

A methylation defect at the four GNAS-DMRs was detected, confirming the clinical diagnosis. Complementary techniques revealed the presence of a mixed isodisomy and heterodisomy of chromosome 20. Surprisingly, the GNAS locus was located on the heterodisomic zone.

Conclusions

Paternal uniparental heterodisomy (hUPD) at the GNAS locus is also a genetic defect associated with iPPSD3. In the absence of parental samples, our custom MS-MLPA allows for the detection of a methylation defect at the GNAS locus and flanking DMRs, suggestive of uniparental disomy (UPD). We also suggest updating the actual guidelines to include hUPD at the GNAS locus as a cause of iPPSD3.

Clinical and Cytogenetic Impact of Maternal Balanced Double Translocation: A Familial Case of 15q11.2 Microduplication and Microdeletion Syndromes with Genetic Counselling Implications

BACKGROUND

Balanced chromosomal translocations occur in approximately 0.16 to 0.20% of live births. While most carriers are phenotypically normal, they are at risk of generating unbalanced gametes during meiosis, leading to genetic anomalies such as aneuploidies, deletions, duplications, and gene disruptions. These anomalies can result in spontaneous abortions or congenital anomalies, including neurodevelopmental disorders. Complex chromosomal rearrangements (CCRs) involving more than two chromosomes are rare but further increase the probability of producing unbalanced gametes. Neurodevelopmental disorders such as Angelman syndrome (AS) and duplication 15q11q13 syndrome (Dup15q) are associated with such chromosomal abnormalities.

METHODS

This study describes a family with a de novo maternal balanced double translocation involving chromosomes 13, 19, and 15, resulting in two offspring with unbalanced chromosomal abnormalities. Cytogenetic evaluations were performed using GTG banding, fluorescence in situ hybridization (FISH), and low-pass whole-genome sequencing (LP-WGS). Methylation analysis was conducted using methylation-sensitive high-resolution melting (MS-HRM) to diagnose Angelman syndrome.

RESULTS

The cytogenetic and molecular analyses identified an 8.9 Mb duplication in 15q11.2q13.3 in one child, and an 8.9 Mb deletion in the same region in the second child. Both abnormalities affected critical neurodevelopmental genes, such as SNRPN. FISH and MS-HRM confirmed the chromosomal imbalances and the diagnosis of Angelman syndrome in the second child. The maternal balanced translocation was found to be cryptic, contributing to the complex inheritance pattern.

CONCLUSION

This case highlights the importance of using multiple genetic platforms to uncover complex chromosomal rearrangements and their impact on neurodevelopmental disorders. The findings underscore the need for thorough genetic counseling, especially in families with such rare chromosomal alterations, to manage reproductive outcomes and neurodevelopmental risks.

Comprehensive molecular and clinical findings in 29 patients with multi-locus imprinting disturbance

BACKGROUND

Multi-locus imprinting disturbance (MLID) with methylation defects in various differentially methylated regions (DMRs) has recently been identified in approximately 150 cases with imprinting disorders (IDs), and deleterious variants have been found in genes related to methylation maintenance of DMRs, such as those encoding proteins constructing the subcortical maternal complex (SCMC), in a small fraction of patients and/or their mothers. However, integrated methylation analysis for DMRs and sequence analysis for MLID-causative genes in MLID cases and their mothers have been performed only in a single study focusing on Beckwith-Wiedemann syndrome (BWS) and Silver-Russell syndrome (SRS) phenotypes.

RESULTS

Of 783 patients with various IDs we have identified to date, we examined a total of 386 patients with confirmed epimutation and 71 patients with epimutation or uniparental disomy. Consequently, we identified MLID in 29 patients with epimutation confirmed by methylation analysis for multiple ID-associated DMRs using pyrosequencing and/or methylation-specific multiple ligation-dependent probe amplification. MLID was detected in approximately 12% of patients with BWS phenotype and approximately 5% of patients with SRS phenotype, but not in patients with Kagami-Ogata syndrome, Prader-Willi syndrome, or Angelman syndrome phenotypes. We next conducted array-based methylation analysis for 78 DMRs and whole-exome sequencing in the 29 patients, revealing hypomethylation-dominant aberrant methylation patterns in various DMRs of all the patients, eight probably deleterious variants in genes for SCMC in the mothers of patients, and one homozygous deleterious variant in ZNF445 in one patient. These variants did not show gene-specific methylation disturbance patterns. Clinically, neurodevelopmental delay and/or intellectual developmental disorder (ND/IDD) was observed in about half of the MLID patients, with no association with the identified methylation disturbance patterns and genetic variants. Notably, seven patients with BWS phenotype were conceived by assisted reproductive technology (ART).

CONCLUSIONS

The frequency of MLID was 7.5% (29/386) in IDs caused by confirmed epimutation. Furthermore, we revealed diverse patterns of hypomethylation-dominant methylation defects, nine deleterious variants, ND/IDD complications in about half of the MLID patients, and a high frequency of MLID in ART-conceived patients.

Sensory Processing Challenges in Children with Neurodevelopmental Disorders and Genetic Conditions: An Observational Study

Sensory processing challenges are crucial yet often neglected aspects in the care of children with neurodevelopmental disorders and genetic conditions. They represent a key area of interest in neuroscience, as they significantly impact children's daily functioning and quality of life. This observational study examines these challenges in a group of 614 children, aged 3 to 14 years and 11 months, divided into three groups: 183 with neurodevelopmental disorders (autism spectrum disorder, attention deficit hyperactivity disorder, developmental delays, and learning disorders), 89 with genetic conditions (22q11.2 deletion syndrome, Williams syndrome, and pseudohypoparathyroidism), and 342 controls. Sensory processing was assessed using Sensory Profile 2 (SP2). Results indicated that children with neurodevelopmental disorders and genetic conditions exhibited significant sensory processing difficulties compared to controls. SP2 identified distinct sensory challenges across different sensory systems, varying by diagnosis. Notably, genetic conditions appeared to have a more generalised impact across multiple sensory systems, while neurodevelopmental disorders tended to affect specific systems more narrowly. These findings highlight the importance of early identification and tailored evidence-based interventions to address these specific sensory processing issues. Further research should explore the long-term impact of these interventions in these different populations and their integration into broader therapeutic programmes.

Characterization of Digestive Manifestations in Patients with Impaired PTH/PTHrP Signaling Disorder/Pseudohypoparathyroidism

INTRODUCTION

Pseudohypoparathyroidism, newly classified as inactivating PTH/PTHrP signaling disorder (iPPSD) type 2 or type 3, is a rare disease caused by defects in the GNAS imprinted gene that encodes Gsα. The most common phenotype comprises resistance to hormones binding to G protein-coupled receptors such as PTH, PTHrP, or TSH, subcutaneous ossifications, short stature, brachydactyly, and early onset obesity. Uncommon features have been described including sleep apnea, asthma, and resistance to calcitonin. At the national French reference center for rare calcium and phosphate metabolism diseases, a large cohort of patients with iPPSD type 2 and type 3 is followed. Interestingly, digestive manifestations and in particular intractable constipation were regularly reported by families of children with iPPSD type 2 or type 3.

OBJECTIVE

The aim of our study was therefore to specify the frequency and characteristics of digestive manifestations in children followed up for iPPSD2 or iPPSD3 in our reference center.

MATERIAL AND METHODS

Thirty-six patients aged between 2 and 18 years (32 followed up for iPPSD2 and 4 for iPPSD3) were included. Parents completed a specific questionnaire to assess any digestive disorders in their child. The diagnosis of constipation was established using the Bristol visual scale in the event of a score of less than 2 according to stool appearance.

RESULTS

Parents reported constipation through the questionnaires in 22/36 (over 60%) of the children. It was the most frequently reported digestive disorder. Among these 22 children, 19 (87%) had a Bristol score for stool shape and texture between 1 and 2 on a scale of 7, confirming constipation. Dedicated treatment had been initiated for 10 (55%) of them, yet only 3 families (16%) considered this treatment effective. Neonatal vomiting and eating disorders, such as lack of satiety or food selectivity, were also noted in 18 (50%) of patients, as was gastroesophageal reflux present in the neonatal period in 14 (40%) of children. There were no significant differences according to the type of iPPSD or patient age.

CONCLUSION

Our work shows for the first time that digestive manifestations, including constipation, occur frequently in children followed for iPPSD, suggesting a potential role of Gsα and G protein receptors in the digestive tract. It is well known that constipation and digestive symptoms alter quality of life. Early management is therefore essential to improve the quality of life of children followed for iPPSD. Our data need to be confirmed on a larger cohort.

Multi-locus imprinting disturbance (MLID): interim joint statement for clinical and molecular diagnosis

BACKGROUND

Imprinting disorders are rare diseases resulting from altered expression of imprinted genes, which exhibit parent-of-origin-specific expression patterns regulated through differential DNA methylation. A subgroup of patients with imprinting disorders have DNA methylation changes at multiple imprinted loci, a condition referred to as multi-locus imprinting disturbance (MLID). MLID is recognised in most but not all imprinting disorders and is also found in individuals with atypical clinical features; the presence of MLID often alters the management or prognosis of the affected person. Some cases of MLID are caused by trans-acting genetic variants, frequently not in the patients but their mothers, which have counselling implications. There is currently no consensus on the definition of MLID, clinical indications prompting testing, molecular procedures and methods for epigenetic and genetic diagnosis, recommendations for laboratory reporting, considerations for counselling, and implications for prognosis and management. The purpose of this study is thus to cover this unmet need.

METHODS

A comprehensive literature search was conducted resulting in identification of more than 100 articles which formed the basis of discussions by two working groups focusing on clinical diagnosis (n = 12 members) and molecular testing (n = 19 members). Following eight months of preparations and regular online discussions, the experts from 11 countries compiled the preliminary documentation and determined the questions to be addressed during a face-to-face meeting which was held with the attendance of the experts together with four representatives of patient advocacy organisations.

RESULTS

In light of available evidence and expert consensus, we formulated 16 propositions and 8 recommendations as interim guidance for the clinical and molecular diagnosis of MLID.

CONCLUSIONS

MLID is a molecular designation, and for patients with MLID and atypical phenotypes, we propose the alternative term multi-locus imprinting syndrome. Due to the intrinsic variability of MLID, the guidelines underscore the importance of involving experts from various fields to ensure a confident approach to diagnosis, counselling, and care. The authors advocate for global, collaborative efforts in both basic and translational research to tackle numerous crucial questions that currently lack answers, and suggest reconvening within the next 3-5 years to evaluate the research advancements and update this guidance as needed.

A Curious Case of Severe Recurrent Hypocalcemia

Hypocalcemia, characterized by low blood calcium levels, can range from asymptomatic to life-threatening. Common causes include hypoparathyroidism and vitamin D deficiency (VDD). Pseudohypoparathyroidism is a rare metabolic disorder marked by resistance to parathyroid hormone (PTH). This report details a young female presenting with severe hypocalcemia, hyperphosphatemia, and elevated PTH levels. She also had an associated VDD, which complicated the clinical picture. Despite receiving intravenous calcium and oral supplementation, she required extended treatment and readmission. Genetic testing revealed a variant in the CACNA1S gene. Her condition eventually stabilized with a strict, adjusted treatment regimen. This case underscores the importance of a systematic diagnostic approach, prolonged intravenous calcium therapy, and close monitoring. Pseudohypoparathyroidism represents a rare cause of severe hypocalcemia, emphasizing the need for close monitoring and regular follow-up to achieve improved outcomes.

Novel 4.18 Mb deletion resulting in 2q37 microdeletion syndrome combined with PTH resistance found in one Chinese patient

BACKGROUND

2q37 microdeletion syndrome is a rare clinical condition characterized by a series of physical abnormalities. Its Albright hereditary osteodystrophy (AHO)-like manifestations and possible complication of biochemical abnormalities indicating PTH resistance greatly increased the likelihood of misdiagnosis with classic pseudohypoparathyroidism (PHP) caused by GNAS mutation or methylation alteration, even though there have only been six reports of such clinical occasions.

PURPOSE

to investigate the underlying genetic defect in a male patient presenting hypocalcemia, elevated PTH and with a history of kyphosis.

METHOD

clinical information was collected, while the DNA was extracted from peripheral blood and subjected to methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) and exome sequencing.

RESULT

Physical characteristics featuring short stature, obesity, round face, short neck, and shortened 4th metacarpal and laboratory examination of the patient suggested the presence of PTH resistance, which is indicative of PHP. MS-MLPA did not reveal methylation alterations or deletions of GNAS, STX16 or other monogenetic alterations responsible for iPPSDs, but WES revealed a long-range deletion of approximately 4.18 Mb of the 2q37 region that spanned AGAP1 to NDUFA10, indicating that the patient had 2q37 microdeletion syndrome with PTH resistance.

CONCLUSION

After undergoing MS-MLPA and exome sequencing, a novel deletion spanning 4.18 Mb on the 2q37 region was identified in one male patient, clarifying the diagnosis of 2q37 microdeletion syndrome with PTH resistance. The new genetic discovery added to our understanding of the molecular defects that cause inactivating PTH/PTH-related protein signaling disorders (iPPSDs).

Hair follicle-resident progenitor cells are a major cellular contributor to heterotopic subcutaneous ossifications in a mouse model of Albright hereditary osteodystrophy

Heterotopic ossifications (HOs) are the pathologic process by which bone inappropriately forms outside of the skeletal system. Despite HOs being a persistent clinical problem in the general population, there are no definitive strategies for their prevention and treatment due to a limited understanding of the cellular and molecular mechanisms contributing to lesion development. One disease in which the development of heterotopic subcutaneous ossifications (SCOs) leads to morbidity is Albright hereditary osteodystrophy (AHO). AHO is caused by heterozygous inactivation of GNAS, the gene that encodes the α-stimulatory subunit (Gαs) of G proteins. Previously, we had shown using our laboratory's AHO mouse model that SCOs develop around hair follicles (HFs). Here we show that SCO formation occurs due to inappropriate expansion and differentiation of HF-resident stem cells into osteoblasts. We also show in AHO patients and mice that Secreted Frizzled Related Protein 2 (SFRP2) expression is upregulated in regions of SCO formation and that elimination of Sfrp2 in male AHO mice exacerbates SCO development. These studies provide key insights into the cellular and molecular mechanisms contributing to SCO development and have implications for potential therapeutic modalities not only for AHO patients but also for patients suffering from HOs with other etiologies.

A Comprehensive Review of Syndromic Forms of Obesity: Genetic Etiology, Clinical Features and Molecular Diagnosis

Syndromic obesity refers to obesity occurring with additional clinical findings, such as intellectual disability/developmental delay, dysmorphic features, and congenital malformations. PURPOSE OF REVIEW: To present a narrative review regarding the genetic etiology, clinical description, and molecular diagnosis of syndromic obesity, which is a rare condition with high phenotypic variability and genetic heterogeneity. The following syndromes are presented in this review: Prader-Willi, Bardet-Biedl, Pseudohypoparathyroidism, Alström, Smith-Magenis, Cohen, Temple, 1p36 deletion, 16p11.2 microdeletion, Kleefstra, SIM1-related, Börjeson-Forssman-Lehmann, WAGRO, Carpenter, MORM, and MYT1L-related syndromes. RECENT FINDINGS: There are three main groups of mechanisms for syndromic obesity: imprinting, transcriptional activity regulation, and cellular cilia function. For molecular diagnostic, methods of genome-wide investigation should be prioritized over sequencing of panels of syndromic obesity genes. In addition, we present novel syndromic conditions that need further delineation, but evidences suggest they have a higher frequency of obesity. The etiology of syndromic obesity tends to be linked to disrupted neurodevelopment (central) and is associated with a diversity of genes and biological pathways. In the genetic investigation of individuals with syndromic obesity, the possibility that the etiology of the syndromic condition is independent of obesity should be considered. The accurate genetic diagnosis impacts medical management, treatment, and prognosis, and allows proper genetic counseling.

Pseudohypoparathyroidism Type IB with Subclinical Hypothyroidism: a Pedigree Investigation and Literature Review

Pseudohypoparathyroidism (PHP) is a rare genetic disease characterized by hypocalcemia, hyperphosphatemia, and elevated parathyroid hormone (PTH) in serum. Here, we report a case of a patient with pseudohypoparathyroidism type IB (PHPIB) and subclinical hypothyroidism, analyze the clinical and genetic data of his family members, review the relevant literature, and classify and discuss the pathogenesis and clinical characteristics of each subtype. Finally, we discuss the treatment approach to improve clinicians' understanding of the disease.

Identification of a novel GNAS mutation in a family with pseudohypoparathyroidism type 1A

BACKGROUND

Pseudohypoparathyroidism (PHP) is caused by loss-of-function mutations at the GNAS gene (as in the PHP type 1A; PHP1A), de novo or inherited at heterozygous state, or by epigenetic alterations at the GNAS locus (as in the PHP1B). The condition of PHP refers to a heterogeneous group of disorders that share common clinical and biological features of PTH resistance. Manifestations related to resistance to other hormones are also reported in many patients with PHP, in association with the phenotypic picture of Albright hereditary osteodystrophy characterized by short stature, round facies, subcutaneous ossifications, brachydactyly, mental retardation and, in some subtypes, obesity. The purpose of our study is to report a new mutation in the GNAS gene and to describe the significant phenotypic variability of three sisters with PHP1A bearing the same mutation.

CASE PRESENTATION

We describe the cases of three sisters with PHP1A bearing the same mutation but characterized by a significantly different phenotypic picture at onset and during follow-up in terms of clinical features, auxological pattern and biochemical changes. Clinical exome sequencing revealed a never before described heterozygote mutation in the GNAS gene (NM_000516.5 c.118_139 + 51del) of autosomal dominant maternal transmission in the three siblings, confirming the diagnosis of PHP1A.

CONCLUSIONS

This study reported on a novel mutation of GNAS gene and highlighted the clinical heterogeneity of PHP1A characterized by wide genotype-phenotype variability. The appropriate diagnosis has crucial implications for patient care and long-term multidisciplinary follow-up.

Pseudohypoparathyroidism type 1B with involuntary movements: a case report and literature review

Pseudohypoparathyroidism (PHP) is a rare disorder characterized by convulsions, tetany, and sensory abnormalities caused by hypocalcemia due to parathyroid hormone (PTH) resistance. Only few patients present with involuntary movements. We report the case of a 7-yr-old girl with PHP and involuntary movements triggered by running. Initially, she was suspected of having paroxysmal kinesigenic dyskinesia and was treated with carbamazepine (CBZ). Involuntary movements were reduced. However, 2 months post-treatment, she experienced convulsions during a fever. Blood tests and brain computed tomography revealed hypocalcemia, hyperphosphatemia, elevated intact PTH, and calcifications in the frontal cortex and basal ganglia. The patient showed no features of Albright's hereditary osteodystrophy. The involuntary movements disappeared after the discontinuation of CBZ and initiation of calcium and active vitamin D preparations. Methylation-specific multiplex ligation-dependent probe amplification for the GNAS region and microsatellite analysis of chromosome 20 led to the diagnosis of PHP1B caused by epimutation. In 15 reported cases, with or without intracranial calcification, PHP-associated involuntary movements disappeared or became less severe with treatment for hypocalcemia; in eight of 11 cases, they were triggered by exercise or movement. PHP-associated hypocalcemia can trigger exercise-induced involuntary movements owing to lowered serum ionized calcium levels. In such patients, early blood tests are vital for the differential diagnosis of PHP.

Diagnosis and approach of pseudohypoparathyroidism type 1A and related disorders during long term follow-up: a case report

OBJECTIVES

Pseudohypoparathyroidism type 1A (PHP1A) encompasses the association of resistance to multiple hormones, features of Albright hereditary osteodystrophy and decreased Gsα activity. Little is known about the early signs of PHP1A, with a delay in diagnosis. We report two PHP1A cases and their clinical and biochemical findings during a 20-year follow-up.

CASE PRESENTATION

Clinical suspicion was based on obesity, TSH resistance and ectopic ossifications which appeared several months before PTH resistance, at almost 3 years of age. Treatment with levothyroxine, calcitriol and calcium was required in both patients. DNA sequencing of GNAS gene detected a heterozygous pathogenic variant within exon 7 (c.569_570delAT) in patient one and a deletion from XLAS to GNAS-exon 5 on the maternal allele in patient 2. In patient 1, ectopic ossifications that required surgical excision were found. Noticeably, patient 2 displayed adult short stature, intracranial calcifications and psychomotor delay. In terms of weight, despite early diagnosis of obesity, dietary measures were established successfully in both cases.

CONCLUSIONS

GNAS mutations should be considered in patients with obesity, ectopic ossifications and TSH resistance presented in early infancy. These cases emphasize the highly heterogeneous clinical picture PHP1A patients may present, especially in terms of final height and cognitive impairment.

Epileptic seizures and abnormal tooth development as primary presentation of pseudohypoparathyroidism type 1B

Pseudohypoparathyroidism (PHP) is a rare genetic disorder characterised by a non-functioning PTH. Usually, the diagnosis is made following (symptomatic) hypocalcaemia. We describe a case in which epileptic seizures and abnormalities in dental development were the main clinical manifestation of PHP type 1B. This case demonstrates the importance of screening for hypocalcaemia in patients with de novo epileptic seizures. In addition, antiepileptic medications themselves may interfere with calcium-phosphate metabolism, causing or aggravating a hypocalcaemia as well. By correcting the calcium level, a resolution of these symptoms could be obtained.

Clinical and Molecular Characteristics and Long-term Follow-up of Children With Pseudohypoparathyroidism Type IA

CONTEXT

Pseudohypoparathyroidism type IA (PHPIA) is a rare genetic disorder characterized by hormone resistance and a typical phenotype named Albright hereditary osteodystrophy. Unawareness of this rare disease leads to delays in diagnosis.

OBJECTIVE

The aims of this study were to describe the clinical and molecular characteristics of patients with genetically confirmed GNAS mutations and to evaluate their long-term outcomes.

METHODS

A retrospective search for all patients diagnosed with PHPIA in 2 referral centers in Israel was conducted.

RESULTS

Nine children (8 females) belonging to 6 families were included in the study. Five patients had GNAS missense mutations, 2 had deletions, and 2 had frameshift mutations. Four mutations were novel. Patients were referred at a mean age of 2.4 years due to congenital hypothyroidism (5 patients), short stature (2 patients), or obesity (2 patients), with a follow-up duration of up to 20 years. Early obesity was observed in the majority of patients. Elevated parathyroid hormone was documented at a mean age of 3 years; however, hypocalcemia became evident at a mean age of 5.9 years, about 3 years later. All subjects were diagnosed with mild to moderate mental retardation. Female adult height was very short (mean -2.5 SD) and 5 females had primary or secondary amenorrhea.

CONCLUSION

Long-term follow-up of newborns with a combination of congenital hypothyroidism, early-onset obesity, and minor dysmorphic features associated with PHPIA is warranted and molecular analysis is recommended since the complete clinical phenotype may develop a long time after initial presentation.

Pseudohypoparathyroidism: complex disease variants with unfortunate names

Several human disorders are caused by genetic or epigenetic changes involving the GNAS locus on chromosome 20q13.3 that encodes the alpha-subunit of the stimulatory G protein (Gsα) and several splice variants thereof. Thus, pseudohypoparathyroidism type Ia (PHP1A) is caused by heterozygous inactivating mutations involving the maternal GNAS exons 1-13 resulting in characteristic abnormalities referred to as Albright's hereditary osteodystrophy (AHO) that are associated with resistance to several agonist ligands, particularly to parathyroid hormone (PTH), thereby leading to hypocalcemia and hyperphosphatemia. GNAS mutations involving the paternal Gsα exons also cause most of these AHO features, but without evidence for hormonal resistance, hence the term pseudopseudohypoparathyroidism (PPHP). Autosomal dominant pseudohypoparathyroidism type Ib (PHP1B) due to maternal GNAS or STX16 mutations (deletions, duplications, insertions, and inversions) is associated with epigenetic changes at one or several differentially methylated regions (DMRs) within GNAS. Unlike the inactivating Gsα mutations that cause PHP1A and PPHP, hormonal resistance is caused in all PHP1B variants by impaired Gsα expression due to loss of methylation at GNAS exon A/B, which can be associated in some familial cases with epigenetic changes at the other maternal GNAS DMRs. The genetic defect(s) responsible for sporadic PHP1B, the most frequent variant of this disorder, remain(s) unknown for the majority of patients. However, characteristic epigenetic GNAS changes can be readily detected that include a gain of methylation at the neuroendocrine secretory protein (NESP) DMR. Multiple genetic or epigenetic GNAS abnormalities can thus impair Gsα function or expression, consequently leading to inadequate cAMP-dependent signaling events downstream of various Gsα-coupled receptors.

The role of genetic and epigenetic GNAS alterations in the development of early-onset obesity

BACKGROUND

GNAS (guanine nucleotide-binding protein, alpha stimulating) is an imprinted gene that encodes Gsα, the α subunit of the heterotrimeric stimulatory G protein. This subunit mediates the signalling of a diverse array of G protein-coupled receptors (GPCRs), including the melanocortin 4 receptor (MC4R) that serves a pivotal role in regulating food intake, energy homoeostasis, and body weight. Genetic or epigenetic alterations in GNAS are known to cause pseudohypoparathyroidism in its different subtypes and have been recently associated with isolated, early-onset, severe obesity. Given the diverse biological functions that Gsα serves, multiple molecular mechanisms involving various GPCRs, such as MC4R, β2- and β3-adrenoceptors, and corticotropin-releasing hormone receptor, have been implicated in the pathophysiology of severe, early-onset obesity that results from genetic or epigenetic GNAS changes.

SCOPE OF REVIEW

This review examines the structure and function of GNAS and provides an overview of the disorders that are caused by defects in this gene and may feature early-onset obesity. Moreover, it elucidates the potential molecular mechanisms underlying Gsα deficiency-induced early-onset obesity, highlighting some of their implications for the diagnosis, management, and treatment of this complex condition.

MAJOR CONCLUSIONS

Gsα deficiency is an underappreciated cause of early-onset, severe obesity. Therefore, screening children with unexplained, severe obesity for GNAS defects is recommended, to enhance the molecular diagnosis and management of this condition.

Vitamin D deficiency in adulthood: Presentation of 2familial cases simulating pseudohypoparathyroidism

BACKGROUND AND OBJECTIVE

The clinical and biochemical overlap of various pathologies of phosphocalcic metabolism can lead to misdiagnosis and consequent clinical management. One example is pseudohypoparathyroidism, which can be confused with vitamin D-dependent rickets (VDDR1) if appropriate biochemical determinations are not performed.

PATIENTS AND METHODS

Two pairs of siblings, from independent families, were clinically diagnosed in adolescence with pseudohypoparathyroidism due to hypocalcaemia, elevated parathyroid hormone levels and normal or elevated phosphorus values. After ruling out alterations in GNAS, a massive sequencing study of genes associated with other differential diagnoses was carried out.

RESULTS

Two genetic variants in the CYP27B1 gene potentially associated with the phenotype were identified. Pathogenic variants in this gene are associated with VDDR1A. Clinical-biochemical re-evaluation of the patients confirmed this diagnosis and treatment was adapted.

CONCLUSIONS

Although VDDR1A is an infrequently diagnosed pathology in adulthood, in cases of hypocalcaemia with elevated PTH values, determination of the 1,25(OH)2D3 and 25(OH)D3 forms of vitamin D is relevant to reach a correct diagnosis.

(Epi)genetic and clinical characteristics in 84 patients with pseudohypoparathyroidism type 1B

OBJECTIVE

Pseudohypoparathyroidism type 1B (PHP1B) caused by methylation defects of differentially methylated regions (DMRs) on the GNAS locus can be categorized into groups according to etiologies and methylation defect patterns of the DMRs. The aim of this study was to clarify the clinical characteristics of each group.

DESIGN

Comprehensive molecular analyses consisting of methylation, copy number, and microsatellite analyses.

METHODS

Eighty-four patients with PHP1B were included in this study. We classified them into 5 groups, namely, autosomal dominant inheritance-PHP1B (Group 1, G1), sporadic-PHP1B (G2), and atypical-PHP1B (G3-G5), based on the methylation defect patterns in 4 DMRs on the GNAS locus and etiologies and evaluated the clinical findings in each group and compared them among the groups.

RESULTS

G2 had the youngest age and the highest serum intact parathyroid hormone levels among the 5 groups at the time of diagnosis. The most common symptoms at the time of diagnosis were tetany in G1, and seizures or loss of consciousness in G2. Albright's hereditary osteodystrophy and PHP-suggestive features were most frequently observed in the G2 proband. Nine patients had neurodevelopmental disorders (NDs) consisting of mild to borderline intellectual disability and/or developmental delay. There were no significant correlations between the average methylation ratios of 7 CpG sites in the GNAS-A/B:TSS-DMR and hormonal and biochemical findings.

CONCLUSION

This study revealed the differences in some clinical characteristics, particularly clinical features, and ages at the time of diagnosis between G2 and other groups and detailed NDs observed in some patients with PHP1B.

C-Cell Hyperplasia and Cystic Papillary Thyroid Carcinoma in a Patient with Type 1B Pseudohypoparathyroidism and Hypercalcitoninaemia: Case Report and Review of the Literature

Hypercalcitoninaemia has been described in patients with pseudohypoparathyroidism (PHP) type 1A and 1B. Elevated calcitonin levels are thought to result from impaired Gsα receptor signaling, leading to multiple hormone resistance. Evidence on the risk of medullary thyroid carcinoma (MTC) or C-cell hyperplasia in PHP patients with hypercalcitoninaemia is lacking. A 43-year-old Caucasian man was referred to our endocrinology clinic for chronic hypocalcemia associated with elevated serum parathormone levels and a single cystic thyroid nodule. The patient did not show skeletal deformities, and screening for concomitant hormone resistances was negative, except for the presence of elevated serum calcitonin levels. The workup led to a molecular diagnosis of sporadic PHP1B. Fine needle aspiration of the thyroid nodule was not diagnostic. The calcium stimulation test yielded an abnormal calcitonin response. Given the scarcity of data on the risk of thyroid malignancy in PHP and calcium stimulation test results, total thyroidectomy was performed. Histological examination revealed cystic papillary thyroid cancer in a background of diffuse C-cell hyperplasia. To our knowledge, we are the first to describe a rare form of thyroid cancer combined with C-cell hyperplasia in a patient with PHP and hypercalcitoninaemia. In the present case, a mere receptor resistance might not fully explain the elevated calcitonin levels, suggesting that hypercalcitoninaemia should be carefully evaluated in PHP patients, especially in the case of concomitant thyroid nodules. Further studies on larger cohorts are needed to elucidate this topic.

A novel mutation in PTHLH in a family with a variable phenotype with brachydactyly, short stature, oligodontia and developmental delay

Mutations in PTHLH (PTH-like hormone), cause brachydactyly type E (BDE) characterized by shortening of metacarpals, metatarsals and/or phalanges with short stature. In this report we describe three siblings and their mother with a novel heterozygous mutation c.25 T > C, p.Trp9Arg in exon 2 of the PTHLH gene. Beside the known clinical features of PTHLH mutations all had a delay in speech and language development, unknown if this is related to the mutation. Patients with PTHLH mutation may have a variable phenotypic presentation.

Explorative research on glucolipid metabolism and levels of adipokines in pseudohypoparathyroidism type 1 patients

BACKGROUND

Pseudohypoparathyroidism type 1 (PHP1) is a rare disease featuring hypocalcemia and elevated PTH level. Though disturbed calcium and phosphorus metabolism under PTH resistant have been widely studied, glucolipid metabolism abnormalities observed in PHP1 patients have received little attention. The aim of this research is to explore the glucolipid metabolism features in a rather large cohort of PHP1 patient. In the current study, PHP1 patients and primary hyperparathyroidism patients as well as normal control were recruited for the investigation. Glucolipid metabolic indices as well as the level of four adipokines were examined.

RESULTS

A total of 49 PHP1 patients, 64 PHPT patients and 30 healthy volunteers were enrolled. A trend of higher HOMA-β index was found in PHP1 patients than normal controls (median 97.08% vs 68.19%, p = 0.060). Both the PHP1 and PHPT group presented with significantly lower TNFα level compared to normal controls (average 10.74 pg/ml and 12.53 pg/ml vs 15.47 pg/ml, p = 0.002 and 0.041, respectively). FGF21 level was significantly higher in PHPT group than in PHP1 group (median 255.74 pg/ml vs 167.46 pg/ml, p = 0.019). No significant difference in glucolipid metabolic indices and adipokines was found between PHP1A or PHP1B patients and normal controls, while overweight/obese PHP1 patients tended to have higher leptin than normal-BMI cases (p = 0.055). Multiple linear regression analysis showed BMI rather than PTH or HOMA-IR to be an independent variable of leptin in PHP1.

CONCLUSION

Metabolic stress given upon especially overweight PHP1 patients may resulted in possible β-cell compensation. Elevated TNFα may be related with hyper-PTH level regardless of calcium level.

Prevalence of Pseudohypoparathyroidism and Nonsurgical Hypoparathyroidism in Japan in 2017: A Nationwide Survey

BACKGROUND

Pseudohypoparathyroidism (PHP) and nonsurgical hypoparathyroidism (NS-HypoPT) are rare diseases with hypocalcemia, hyperphosphatemia, and high and low parathyroid hormone levels, respectively. In Japan, over 20 years have passed since the last survey on these diseases. We carried out a nationwide cross-sectional survey to estimate the prevalence of these diseases in 2018.

METHODS

We conducted a nationwide mail-based survey targeting hospitals in 2018. From a total of 13,156 departments throughout Japan, including internal medicine, pediatrics, neurology, and psychiatry, 3,501 (27%) departments were selected using a stratified random sampling method. We asked each included department to report the number of patients with PHP and NS-HypoPT in 2017.

RESULTS

The overall survey response rate was 52.0% (1,807 departments). The estimated number of patients with PHP and NS-HypoPT was 1,484 (95% confidence interval [CI], 1,143-1,825) and 2,304 (95% CI, 1,189-3,419), respectively; the prevalence per 100,000 population was 1.2 and 1.8, respectively.

CONCLUSION

In this study, we generated estimates of the national prevalence of PHP and NS-HypoPT in Japan during 2017, which were found to be higher than those previously reported.

A Case of Pseudohypoparathyroidism Misdiagnosed as Idiopathic Epilepsy for 5 Years: Clinical Analysis and Follow-up Outcomes

We report a 15-year-old Chinese girl who presented with intermittent seizure episodes and had been misdiagnosed as having idiopathic epilepsy 5 years previously. Laboratory testing revealed hypocalcemia, hyperphosphatemia, and a high parathyroid hormone (PTH) concentration. She was subsequently shown to have pseudohypoparathyroidism type Ib (PHPIb) based on the results of methylation analysis of the GNAS gene, which showed a loss of methylation of the differentially methylated regions (DMR) of GNAS-AS1, GNAS-XL, and GNAS-A/B; and a gain of methylation of the DMR of the GNAS-NESP55 region. We adjusted the patient's medication by prescribing calcium and calcitriol supplements, and gradually reduced the doses of antiepileptic drugs, until they had been completely discontinued. As a result, the patient did not experience any further seizures or epileptiform symptoms; and had normal plasma calcium, phosphorus, and 25-hydroxyvitamin D concentrations and 24-hour urinary calcium excretion. In addition, her PTH concentration gradually normalized over 12 months, and no urinary stones were found on ultrasonographic examination. In conclusion, the clinical presentation of PHP is complex, and the condition is often misdiagnosed. The diagnosis and follow-up of the present patient have provide valuable insights that should contribute to informed clinical decision-making and the implementation of appropriate treatment strategies.

Venous Thrombosis in a Pseudohypoparathyroidism Patient with a Novel GNAS Frameshift Mutation and Complete Resolution of Vascular Calcifications with Acetazolamide Treatment

INTRODUCTION

Pseudohypoparathyroidism type IA (PHP1A) is characterized by end-organ resistance to multiple hormones and Albright's hereditary osteodystrophy (AHO). PHP1A is caused by inactivating mutations of the GNAS gene encoding the α-subunit of the stimulatory G protein (Gsα). In line with the underlying genetic defect, impaired inhibition of platelet aggregation has been demonstrated in some patients. However, no PHP1A case with thrombotic events has been described. Also, PHP1A cases typically have subcutaneous ossifications, but soft tissue calcifications are another common finding. Treatment options for those and other nonhormonal features of PHP1A are limited.

CASE PRESENTATION

A female patient presented with short stature, fatigue, and exercise-induced carpopedal spasms at age 117/12 years. Diagnosis of PHP1A was made based on hypocalcemia, hyperphosphatemia, elevated serum parathyroid hormone, and AHO features, including short stature and brachydactyly. A novel frameshift variant was detected in the last exon of GNAS (c.1065_1068delGCGT, p.R356Tfs*47), showing complete loss of baseline and receptor-stimulated activity in transfected cells. The patient developed venous thrombosis and vascular and subcutaneous calcifications on both forearms after venous puncture on the right and extravasation of calcium gluconate during treatment on the left. The thrombosis and calcifications completely resolved following treatment with low-molecular-weight heparin and acetazolamide for 5 and 8 months, respectively.

CONCLUSIONS

This case represents the first PHP1A patient displaying thrombosis and the first successful use of acetazolamide for PHP1A-associated soft tissue calcifications, thus providing new insights into the treatment of non-endocrinological features in this disease.

Neonatal and Early Infancy Features of Patients With Inactivating PTH/PTHrP Signaling Disorders/Pseudohypoparathyroidism

BACKGROUND

Pseudohypoparathyroidism (PHP) and related disorders newly referred to as inactivating PTH/PTHrP signaling disorders (iPPSD) are rare endocrine diseases. Many clinical features including obesity, neurocognitive impairment, brachydactyly, short stature, parathyroid hormone (PTH) resistance, and resistance to other hormones such as thyroid-stimulating hormone (TSH) have been well described, yet they refer mainly to the full development of the disease during late childhood and adulthood.

OBJECTIVE

A significant delay in diagnosis has been reported; therefore, our objective is to increase awareness on neonatal and early infancy presentation of the diseases. To do so, we analyzed a large cohort of iPPSD/PHP patients.

METHODS

We included 136 patients diagnosed with iPPSD/PHP. We retrospectively collected data on birth and investigated the rate of neonatal complications occurring in each iPPSD/PHP category within the first month of life.

RESULTS

Overall 36% of patients presented at least one neonatal complication, far more than the general population; when considering only the patients with iPPSD2/PHP1A, it reached 47% of the patients. Neonatal hypoglycemia and transient respiratory distress appeared significantly frequent in this latter group, ie, 10.5% and 18.4%, respectively. The presence of neonatal features was associated with earlier resistance to TSH (P < 0.001) and with the development of neurocognitive impairment (P = 0.02) or constipation (P = 0.04) later in life.

CONCLUSION

Our findings suggest that iPPSD/PHP and especially iPPSD2/PHP1A newborns require specific care at birth because of an increased risk of neonatal complications. These complications may predict a more severe course of the disease; however, they are unspecific which likely explains the diagnostic delay.

GNAS locus: bone related diseases and mouse models

GNASis a complex locus characterized by multiple transcripts and an imprinting effect. It orchestrates a variety of physiological processes via numerous signaling pathways. Human diseases associated with the GNAS gene encompass fibrous dysplasia (FD), Albright's Hereditary Osteodystrophy (AHO), parathyroid hormone(PTH) resistance, and Progressive Osseous Heteroplasia (POH), among others. To facilitate the study of the GNAS locus and its associated diseases, researchers have developed a range of mouse models. In this review, we will systematically explore the GNAS locus, its related signaling pathways, the bone diseases associated with it, and the mouse models pertinent to these bone diseases.

Pseudohypoparathyroidism versus signaling disorder: A case report

Pseudohypoparathyroidism is a terminology used to describe a group of metabolic disorders characterized by parathyroid hormone resistance. Patients with pseudohypoparathyroidism have hypocalcemia, hyperphosphatemia, and elevated serum parathyroid hormone. This methylation defect leads to signaling abnormalities in the parathyroid hormone and parathyroid hormone-related peptide receptor. We present a 40-year-old African American male who was referred to our endocrinology clinic for hypocalcemia. On physical examination, his body mass index was 34.3 kg/m2 and he was found to have a round face, and several subcutaneous nodules on his scalp, hands, and legs. Laboratory findings revealed hypocalcemia, hyperphosphatemia, and elevated levels of intact parathyroid hormone and thyroid stimulating hormone (TSH). His hand X-ray showed brachydactyly of all metacarpal bones, and soft tissue calcifications. Brain CT indicated dense calcifications in the subcortical region, bilateral basal ganglia, bilateral thalami, bilateral cerebellum and vermis, and soft tissue calcifications in the scalp. The "inactivating parathyroid hormone/parathyroid hormone-related peptide signaling disorder" diagnostic approach suggested by the Euro pseudohypoparathyroidism network was applied to the patient, who was diagnosed with parathyroid hormone signaling disorder. Compared to the old pseudohypoparathyroidism classification and the 2018 Pseudohypoparathyroidism International Consensus Statement Report, the inactivating parathyroid hormone/parathyroid hormone-related peptide signaling disorder cluster classification appears to be more flexible, and easier to use. It also accommodates future inclusion of genetic mutations associated with hormonal signaling disorders. Adoption of the inactivating parathyroid hormone/parathyroid hormone-related peptide signaling disorder classification remains limited, and further larger studies are needed to compare the three approaches.

Application of calcium-to-phosphorus (Ca/P) ratio in the diagnosis of pseudohypoparathyroidism: another piece in the puzzle of diagnosis of Ca-P metabolism disorders

Objective

The serum calcium (Ca)-to-phosphorus (P) ratio has been proposed to identify patients with primary hyperparathyroidism and chronic hypoparathyroidism (HPT), but it has never been tested in pseudohypoparathyroidism (PHP). The aim of this study was to test the performance of Ca/P ratio in PHP diagnosis compared with that in healthy subjects and patients with HPT for differential diagnosis.

Design

A retrospective, cross-sectional, and observational study was carried out.

Methods

Serum Ca, P, creatinine, parathyroid hormone (PTH), and albumin were collected. Ca and P were expressed in mmol/L. Ca/P diagnostic performance was evaluated by receiver operating characteristic curve, sensitivity, specificity, and accuracy.

Results

A total of 60 patients with PHP, 60 patients with HPT, and 120 controls were enrolled. The Ca/P ratio was lower in patients with PHP and HPT than that in controls (p < 0.0001). The cutoff of 1.78 (2.32 if Ca and P measured in mg/dL) for Ca/P ratio could identify patients with PHP and HPT among the entire cohort (sensitivity and specificity of 76%). No valid cutoff of Ca/P was found to distinguish patients with PHP from patients with HPT; in this case, PTH above 53.0 ng/dL identified patients with PHP (sensitivity and specificity of 100%). The index (Ca/P × PTH) above 116 ng/L recognized patients with PHP from controls (sensitivity of 84.7% and specificity of 87.4%), whereas (Ca/P × PTH) below 34 ng/L recognized patients with HPT from controls (sensitivity of 88.9% and specificity of 90.8%).

Conclusions

The Ca/P ratio below 1.78 (2.32 CU) is highly accurate to identify patients with PHP and HPT, although it is not reliable to differentiate these two conditions. The index (Ca/P × PTH) is excellent to specifically recognize PHP or HPT from healthy subjects.

[The enigma of Henry IV's disease: Did he suffer from McCune-Albright syndrome/fibrous dysplasia?]

BACKGROUND

Henry IV King of Castile, last king of the Trastámara dynasty, was the brother of Isabella the Catholic. He is known as "the impotent". Based on previous descriptions by historians and biographers, Gregorio Marañón in 1922 described him as "eunuchoid dysplastic with acromegalic reaction and clear schizoid features".

METHODS

In 1946, a post-mortem inspection was carried out on the mummified corpse found in the Monastery of Guadalupe. A written document and some photographs were recorded. We have collected the signs and symptoms described and applied the international classification of diseases recommended by the World Health Organisation, ICD11-2023. We have relied on the coins issued in the money of Henry IV, on which we have identified enlargement of the thyroid gland.

RESULTS

With the data available at this time, we suggest that Henry IV most probably suffered from: facial and polyostotic bone dysplasia, kyphosis, limb limping, multiple endocrine disorders, acromegaly with macrognatia, nodular thyroid disease, malodorous diaphoresis, erectile dysfunction, hypospadias, abnormal sexual development, "feminoid pelvis", abdominal colic, oligodontia and dental displacement. It is possible that he also suffered from: precocious puberty, renal lithiasis with debilitating phosphaturia, carpal tunnel, thrombopenia and growth hormone-producing pituitary hyperplasia or adenoma.

CONCLUSION

We suggest that Henry IV may have suffered from McCune-Albrigth syndrome associated with fibrous dysplasia, a rare disease due to gain-of-function mutations in the GNAS gene.

Imprinted Long Non-Coding RNAs in Mammalian Development and Disease

Imprinted genes play diverse roles in mammalian development, homeostasis, and disease. Most imprinted chromosomal domains express one or more long non-coding RNAs (lncRNAs). Several of these lncRNAs are strictly nuclear and their mono-allelic expression controls in cis the expression of protein-coding genes, often developmentally regulated. Some imprinted lncRNAs act in trans as well, controlling target gene expression elsewhere in the genome. The regulation of imprinted gene expression-including that of imprinted lncRNAs-is susceptible to stochastic and environmentally triggered epigenetic changes in the early embryo. These aberrant changes persist during subsequent development and have long-term phenotypic consequences. This review focuses on the expression and the cis- and trans-regulatory roles of imprinted lncRNAs and describes human disease syndromes associated with their perturbed expression.

Hypoparathyroidism in children and adolescents

Hypoparathyroidism is characterized by insufficient parathyroid hormone (PTH) release from the parathyroid glands to maintain serum calcium level within normal limits and unresponsiveness of target tissues despite normal serum PTH level. Hypoparathyroidism is defined as low or inappropriately normal serum PTH level. In this narrative review, we discuss the etiology of hypoparathyroidism in children.

Co-occurrence of Beckwith-Wiedemann syndrome and pseudohypoparathyroidism type 1B: coincidence or common molecular mechanism?

Imprinting disorders are congenital diseases caused by dysregulation of genomic imprinting, affecting growth, neurocognitive development, metabolism and cancer predisposition. Overlapping clinical features are often observed among this group of diseases. In rare cases, two fully expressed imprinting disorders may coexist in the same patient. A dozen cases of this type have been reported so far. Most of them are represented by individuals affected by Beckwith-Wiedemann spectrum (BWSp) and Transient Neonatal Diabetes Mellitus (TNDM) or BWSp and Pseudo-hypoparathyroidism type 1B (PHP1B). All these patients displayed Multilocus imprinting disturbances (MLID). Here, we report the first case of co-occurrence of BWS and PHP1B in the same individual in absence of MLID. Genome-wide methylation and SNP-array analyses demonstrated loss of methylation of the KCNQ1OT1:TSS-DMR on chromosome 11p15.5 as molecular cause of BWSp, and upd(20)pat as cause of PHP1B. The absence of MLID and the heterodisomy of chromosome 20 suggests that BWSp and PHP1B arose through distinct and independent mechanism in our patient. However, we cannot exclude that the rare combination of the epigenetic defect on chromosome 11 and the UPD on chromosome 20 may originate from a common so far undetermined predisposing molecular lesion. A better comprehension of the molecular mechanisms underlying the co-occurrence of two imprinting disorders will improve genetic counselling and estimate of familial recurrence risk of these rare cases. Furthermore, our study also supports the importance of multilocus molecular testing for revealing MLID as well as complex cases of imprinting disorders.