Simpson-Golabi-Behmel syndrome types I and II

Simpson-Golabi-Behmel syndrome

The Simpson-Golabi-Behmel syndrome (SGBS; OMIM 312870) is an overgrowth/multiple congenital anomalies/dysplasia condition, inherited as an X-linked semi-dominant trait, with variable expressivity in males and reduced penetrance and expressivity in females. The clinical spectrum is broad, ranging from mild manifestations in both males and females to multiple malformations and neonatal death in the more severely affected cases. An increased risk of neoplasia is reported, requiring periodical surveillance. Intellectual development is normal in most cases. SGBS is caused by a loss-of-function mutation of the GPC3 gene, either deletions or point mutations, distributed all over the gene. Notably, GPC3 deletion/point mutations are not found in a significant proportion of clinically diagnosed SGBS cases. The protein product GPC3 is a glypican functioning as a receptor for Hh at the cell surface, involved in the Hh-Ptc-Smo signaling pathway, a regulator of cellular growth.

Molecular Pathways Governing the Termination of Liver Regeneration

The liver has the unique capacity to regenerate, and up to 70% of the liver can be removed without detrimental consequences to the organism. Liver regeneration is a complex process involving multiple signaling networks and organs. Liver regeneration proceeds through three phases: the initiation phase, the growth phase, and the termination phase. Termination of liver regeneration occurs when the liver reaches a liver-to-body weight that is required for homeostasis, the so-called "hepatostat." The initiation and growth phases have been the subject of many studies. The molecular pathways that govern the termination phase, however, remain to be fully elucidated. This review summarizes the pathways and molecules that signal the cessation of liver regrowth after partial hepatectomy and answers the question, "What factors drive the hepatostat?" SIGNIFICANCE STATEMENT: Unraveling the pathways underlying the cessation of liver regeneration enables the identification of druggable targets that will allow us to gain pharmacological control over liver regeneration. For these purposes, it would be useful to understand why the regenerative capacity of the liver is hampered under certain pathological circumstances so as to artificially modulate the regenerative processes (e.g., by blocking the cessation pathways) to improve clinical outcomes and safeguard the patient's life.

Nontuberculous Mycobacteria, Mucociliary Clearance, and Bronchiectasis

Nontuberculous mycobacteria (NTM) are environmental and ubiquitous, but only a few species are associated with disease, often presented as nodular/bronchiectatic or cavitary pulmonary forms. Bronchiectasis, airways dilatations characterized by chronic productive cough, is the main presentation of NTM pulmonary disease. The current Cole's vicious circle model for bronchiectasis proposes that it progresses from a damaging insult, such as pneumonia, that affects the respiratory epithelium and compromises mucociliary clearance mechanisms, allowing microorganisms to colonize the airways. An important bronchiectasis risk factor is primary ciliary dyskinesia, but other ciliopathies, such as those associated with connective tissue diseases, also seem to facilitate bronchiectasis, as may occur in Lady Windermere syndrome, caused by M. avium infection. Inhaled NTM may become part of the lung microbiome. If the dose is too large, they may grow excessively as a biofilm and lead to disease. The incidence of NTM pulmonary disease has increased in the last two decades, which may have influenced the parallel increase in bronchiectasis incidence. We propose that ciliary dyskinesia is the main promoter of bronchiectasis, and that the bacteria most frequently involved are NTM. Restoration of ciliary function and impairment of mycobacterial biofilm formation may provide effective therapeutic alternatives to antibiotics.

Simpson-Golabi-Behmel syndrome type 1 with normal birth parameters

A newborn baby born at 34 weeks and 5 days gestation was admitted for prematurity, dysmorphic features and congenital heart defects. Antenatal scan at 21 weeks showed a large-for-gestational-age foetus with a large abdominal circumference and liver, ventricular septal defect, right prominent renal pelvis and echogenic bowel. Antenatal genetic tests for overgrowth syndromes were negative. The mother had early onset pre-eclampsia. After birth, an overgrowth syndrome was still suspected despite the baby having normal birth parameters. Raw data of the trio whole exome sequencing from the amniocentesis sample were manually inspected. Hemizygous exon 7 deletion in the GPC3 gene was found, and a postnatal diagnosis of Simpson-Golabi-Behmel syndrome, a rare overgrowth syndrome, was made. This case report discusses the significance of antenatal findings, an atypical presentation of a rare syndrome and the obstacles of diagnostic genetic testing.

Interpregnancy weight change as a potential risk factor for large-for-gestational-age infants: the Japan Environment and Children's Study

OBJECTIVE

This study aimed to estimate the impact of interpregnancy weight change from the first to the second pregnancy on the risk of infants being large for gestational age (LGA).

METHODS

This nationwide prospective birth cohort analysis included 3245 women who delivered their first two live singletons between 2011 and 2014. Interpregnancy weight change was calculated as the difference between the prepregnancy body mass index (BMI) of the first and second pregnancies. LGA infants were compared among three interpregnancy weight change groups: weight loss (a BMI loss >1 unit), weight gain (a BMI gain >1 unit), and stable weight (BMI maintained within - 1 to <1 unit). Interpregnancy weight change was assessed in mothers with a BMI <25 and ≥25 kg/m², and adjusted odds ratios (ORs) were calculated for LGA infants by multiple logistic regression.

RESULTS

The incidence of LGA infants was 8.6% (279 out of 3245). Compared with the stable weight group, interpregnancy weight gain was associated with an increased risk of infants being LGA (adjusted OR: 1.69, 95% confidence interval: 1.21-2.36) in the normal BMI (<25 kg/m²) group. In contrast, in the overweight/obese BMI (≥25 kg/m²) group, interpregnancy BMI was not a significant risk factor for LGA infants.

CONCLUSIONS

Accurate risk stratification using interpregnancy BMI could assist the clinical management of women with a normal BMI who are at risk of delivering LGA infants.

Snijders Blok-Campeau Syndrome: Description of 20 Additional Individuals with Variants in CHD3 and Literature Review

Snijders Blok-Campeau syndrome (SNIBCPS, OMIM# 618205) is an extremely infrequent disease with only approximately 60 cases reported so far. SNIBCPS belongs to the group of neurodevelopmental disorders (NDDs). Clinical features of patients with SNIBCPS include global developmental delay, intellectual disability, speech and language difficulties and behavioral disorders like autism spectrum disorder. In addition, patients with SNIBCPS exhibit typical dysmorphic features including macrocephaly, hypertelorism, sparse eyebrows, broad forehead, prominent nose and pointed chin. The severity of the neurological effects as well as the presence of other features is variable among subjects. SNIBCPS is caused likely by pathogenic and pathogenic variants in CHD3 (Chromodomain Helicase DNA Binding Protein 3), which seems to be involved in chromatin remodeling by deacetylating histones. Here, we report 20 additional patients with clinical features compatible with SNIBCPS from 17 unrelated families with confirmed likely pathogenic/pathogenic variants in CHD3. Patients were analyzed by whole exome sequencing and segregation studies were performed by Sanger sequencing. Patients in this study showed different pathogenic variants affecting several functional domains of the protein. Additionally, none of the variants described here were reported in control population databases, and most computational predictors suggest that they are deleterious. The most common clinical features of the whole cohort of patients are global developmental delay (98%) and speech disorder/delay (92%). Other frequent features (51-74%) include intellectual disability, hypotonia, hypertelorism, abnormality of vision, macrocephaly and prominent forehead, among others. This study expands the number of individuals with confirmed SNIBCPS due to pathogenic or likely pathogenic variants in CHD3. Furthermore, we add evidence of the importance of the application of massive parallel sequencing for NDD patients for whom the clinical diagnosis might be challenging and where deep phenotyping is extremely useful to accurately manage and follow up the patients.

Lipid Nanoparticles as a Shuttle for Anti-Adipogenic miRNAs to Human Adipocytes

Obesity and type 2 diabetes are major health burdens for which no effective therapy is available today. One treatment strategy could be to balance the metabolic functions of adipose tissue by regulating gene expressions using miRNAs. Here, we have loaded two anti-adipogenic miRNAs (miR26a and miR27a) into a pegylated lipid nanoparticle (PEG-LNP) formulation by a single-step microfluidic-assisted synthesis step. For the miRNA-loaded LNPs, the following system properties were determined: particle size, zeta potential, miRNA complexation efficiency, and cytotoxicity. We have used a human preadipocyte cell line to address the transfection efficiency and biological effects of the miRNA candidates at the gene and protein level. Our findings revealed that the upregulation of miR27a in preadipocytes inhibits adipogenesis by the downregulation of PPARγ and the reduction of lipid droplet formation. In contrast, miR26a transfection in adipocytes induced white adipocyte browning detected as the upregulation of uncoupling protein 1 (UCP1) as a marker of non-shivering thermogenesis. We conclude that the selective delivery of miRNAs by PEG-LNPs to adipocytes could offer new perspectives for the treatment of obesity and related metabolic diseases.

Prenatal diagnosis of Simpson-Golabi-Behmel syndrome type 1 with an 814 kb Xq26.2 deletion with the initial presentation of a thick nuchal fold

OBJECTIVE

Simpson-Golabi-Behmel syndrome type 1 (SGBS1) is a rare X-linked recessive disorder characterized by overgrowth and multiple anomalies. Most clinical diagnoses of SGBS1 are made postnatally. We present the case of a pregnant woman in whom the fetus presented with a thick nuchal fold 5.6 mm at 15 weeks of gestation, leading to the prenatal diagnosis of SGBS1 with Xq26.2 (133408101-134221889) deletion.

CASE REPORT

We report the case of a 34-year-old pregnant woman with the initial presentation of fetal thick nuchal fold 5.6 mm at 15 weeks of gestation. Amniocentesis of the fetal karyotype revealed a normal 46, XY, and single nucleotide polymorphism array showed Xq26.2 (133408101-134221889) deletion. Prenatal ultrasound at 21 weeks of gestation revealed a thick nuchal fold, hepatomegaly, nephromegaly, congenital diaphragmatic hernia, hypospadias, and polyhydramnios. Fetal magnetic resonance imaging revealed hepatomegaly, nephromegaly, congenital diaphragmatic hernia, and right lung hypoplasia. The woman had her pregnancy terminated at 24 weeks of gestation. The proband had a general appearance of low-set ears, hypertelorism, a large tongue, and hypospadias and some unique findings on autopsy, including hepatomegaly, right hiatal hernia, liver extensive extramedullary hematopoiesis, kidney marked congestion, and focal hemorrhage.

DISCUSSION

The main prenatal ultrasound findings that alert clinical doctors about the possible diagnosis of SGBS1 included macrosomia, polyhydramnios, organomegaly, renal malformations, congenital diaphragmatic hernia, and cardiac anomalies. Our case underscores the importance of fetal karyotyping combined with single nucleotide polymorphism array when a thick nuchal fold is found. Genetic counseling is essential in SGBS1, and prenatal testing or preimplantation testing for subsequent pregnancies is necessary to identify possible pathogenic variants.

Obesity and diabetes: the final frontier

INTRODUCTION

Obesity is a key target in the treatment and prevention of diabetes and independently to reduce the burden of cardiovascular disease. We reviewed the options now available and anticipated to deal with obesity.

AREAS COVERED

We considered the epidemiology, genetics, and causation of obesity and the relationship to diabetes, and the dietary, pharmaceutical, and surgical management of the condition. The literature search covered both popular media via Google Search and the academic literature as indexed on PubMed with search terms including obesity, childhood obesity, adipocytes, insulin resistance, mechanisms of satiety, bariatric surgery, GLP-1 receptor agonists, and SGLT2 inhibitors.

EXPERT OPINION

Although bariatric surgery has been the primary approach to treating obese individuals, the emergence of agents impacting the brain satiety centers now promises effective, non-invasive treatment of obesity for individuals with and without diabetes. The GLP-1 receptor agonists have assumed the primary role in treating obesity with significant weight loss. Long-term results with semaglutide and tirzepatide are now approaching the success seen with bariatric surgery. Future agents combining the benefits of satiety control and thermogenesis to dissipate caloric excess are under investigation.

GPC3-Unc5 receptor complex structure and role in cell migration

Neural migration is a critical step during brain development that requires the interactions of cell-surface guidance receptors. Cancer cells often hijack these mechanisms to disseminate. Here, we reveal crystal structures of Uncoordinated-5 receptor D (Unc5D) in complex with morphogen receptor glypican-3 (GPC3), forming an octameric glycoprotein complex. In the complex, four Unc5D molecules pack into an antiparallel bundle, flanked by four GPC3 molecules. Central glycan-glycan interactions are formed by N-linked glycans emanating from GPC3 (N241 in human) and C-mannosylated tryptophans of the Unc5D thrombospondin-like domains. MD simulations, mass spectrometry and structure-based mutants validate the crystallographic data. Anti-GPC3 nanobodies enhance or weaken Unc5-GPC3 binding and, together with mutant proteins, show that Unc5/GPC3 guide migrating pyramidal neurons in the mouse cortex, and cancer cells in an embryonic xenograft neuroblastoma model. The results demonstrate a conserved structural mechanism of cell guidance, where finely balanced Unc5-GPC3 interactions regulate cell migration.

The Extracellular Matrix and Neuroblastoma Cell Communication-A Complex Interplay and Its Therapeutic Implications

Neuroblastoma (NB) is a pediatric neuroendocrine neoplasm. It arises from the sympatho-adrenal lineage of neural-crest-derived multipotent progenitor cells that fail to differentiate. NB is the most common extracranial tumor in children, and it manifests undisputed heterogeneity. Unsatisfactory outcomes of high-risk (HR) NB patients call for more research to further inter-relate treatment and molecular features of the disease. In this regard, it is well established that in the tumor microenvironment (TME), malignant cells are engaged in complex and dynamic interactions with the extracellular matrix (ECM) and stromal cells. The ECM can be a source of both pro- and anti-tumorigenic factors to regulate tumor cell fate, such as survival, proliferation, and resistance to therapy. Moreover, the ECM composition, organization, and resulting signaling networks are vastly remodeled during tumor progression and metastasis. This review mainly focuses on the molecular mechanisms and effects of interactions of selected ECM components with their receptors on neuroblastoma cells. Additionally, it describes roles of enzymes modifying and degrading ECM in NB. Finally, the article gives examples on how the knowledge is exploited for prognosis and to yield new treatment options for NB patients.

20 Years with SGBS cells - a versatile in vitro model of human adipocyte biology

20 years ago, we described a human cell strain derived from subcutaneous adipose tissue of an infant supposed to have Simpson-Golabi-Behmel Syndrome (SGBS), thus called “SGBS cells”. Since then, these cells have emerged as the most commonly used cell model for human adipogenesis and human adipocyte biology. Although these adipocyte derived stem cells have not been genetically manipulated for transformation or immortalization, SGBS cells retain their capacity to proliferate and to differentiate into adipocytes for more than 50 population doublings, providing an almost unlimited source of human adipocyte progenitor cells. Original data obtained with SGBS cells led to more than 200 peer reviewed publications comprising investigations on adipogenesis and browning, insulin sensitivity, inflammatory response, adipokine production, as well as co-culture models and cell-cell communication. In this article, we provide an update on the characterization of SGBS cells, present basic methods for their application and summarize results of a systematic literature search on original data obtained with this cell strain.

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.

A prenatal case of Simpson-Golabi-Behmel syndrome type 1 with a 0.26-Mb deletion fragment at Xq26.2 inherited from mother: Case report

RATIONALE

The purpose of this report was to explore how to manage the fetus of Simpson-Golabi-Behmel syndrome type 1 (SGBS1) and to provide a definite diagnosis to guide the following genetic counseling for the pregnancy.

PATIENT CONCERNS

A 24-year-old women, gravida 1, para 0, was 172 cm tall with weight 65 kg. She was referred to our center for counseling due to second-trimester ultrasound screening anomalies at 22 + 5 weeks of gestation age. Meanwhile the ultrasound examination indicated the overgrowth of the fetus. She and her husband were healthy and nonconsanguineous without family history.

DIAGNOSES

The karyotype and copy number variations sequencing (CNV-seq) combined with fetal ultrasound manifestation confirmed the diagnosis of SGBS1.

INTERVENTIONS

No treatment for the fetus.

OUTCOMES

Pregnancy was terminated.

LESSIONS

Once fetal overgrowth and other malformation are revealed in prenatal ultrasound, although without polyhydramnios and organomegaly, SGBS1 should be considered and further genetic testing such as CNV-seq and whole exon sequencing should be conducted to help clinicians provide a definite diagnosis to guide the following genetic counseling and the next pregnancy.

Simpson-Golabi-Behmel syndrome in one of the Dichorionic-diamniotic twin: a case report and literature review

Background

Simpson-Golabi-Behmel syndrome (SGBS) is a rare X-linked overgrowth syndrome. The main clinical manifestations are overgrowth and multiple malformations.

Case presentation

A 38-year-old Chinese woman was pregnant with dichorionic-diamniotic (DCDA) twins after in-vitro fertilization. Series of ultrasound examinations indicated that the measurements (abdominal circumference and estimated foetal weight) of one twin were significantly greater than those of the other one. The genetic testing results of the larger baby indicated of Simpson-Golabi-Behmel syndrome.

Conclusion

SGBS is difficult to diagnose due to different clinical manifestations. Clinicians need to be more aware of typical SGBS’s clinical findings and choose genetic testing methods individually to improve its prenatal diagnosis.

Association between pectus excavatum and congenital genetic disorders: A systematic review and practical guide for the treating physician

BACKGROUND

Pectus excavatum (PE) could be part of a genetic disorder, which then has implications regarding comorbidity, the surgical correction of PE, and reproductive choices. However, referral of a patient presenting with PE for genetic analysis is often delayed because additional crucial clinical signs may be subtle or even missed in syndromic patients. We reviewed the literature to inventory known genetic disorders associated with PE and create a standardized protocol for clinical evaluation.

METHODS

A systematic literature search was performed in electronic databases. Genetic disorders were considered associated with PE if studies reported at least five cases with PE. Characteristics of each genetic disorder were extracted from the literature and the OMIM database in order to create a practical guide for the clinician.

RESULTS

After removal of duplicates from the initial search, 1632 citations remained. Eventually, we included 119 full text articles, representing 20 different genetic disorders. Relevant characteristics and important clinical signs of each genetic disorder were summarized providing a standardized protocol in the form of a scoring list. The most important clinical sign was a positive family history for PE and/or congenital heart defect.

CONCLUSIONS

Twenty unique genetic disorders have been found associated with PE. We have created a scoring list for the clinician that systematically evaluates crucial clinical signs, thereby facilitating decision making for referral to a clinical geneticist.

A Dominant Heterozygous Mutation in COG4 Causes Saul-Wilson Syndrome, a Primordial Dwarfism, and Disrupts Zebrafish Development via Wnt Signaling

Saul-Wilson syndrome (SWS) is a rare, skeletal dysplasia with progeroid appearance and primordial dwarfism. It is caused by a heterozygous, dominant variant (p.G516R) in COG4, a subunit of the conserved oligomeric Golgi (COG) complex involved in intracellular vesicular transport. Our previous work has shown the intracellular disturbances caused by this mutation; however, the pathological mechanism of SWS needs further investigation. We sought to understand the molecular mechanism of specific aspects of the SWS phenotype by analyzing SWS-derived fibroblasts and zebrafish embryos expressing this dominant variant. SWS fibroblasts accumulate glypicans, a group of heparan sulfate proteoglycans (HSPGs) critical for growth and bone development through multiple signaling pathways. Consistently, we find that glypicans are increased in zebrafish embryos expressing the COG4 ^p.G516R variant. These animals show phenotypes consistent with convergent extension (CE) defects during gastrulation, shortened body length, and malformed jaw cartilage chondrocyte intercalation at larval stages. Since non-canonical Wnt signaling was shown in zebrafish to be related to the regulation of these processes by glypican 4, we assessed wnt levels and found a selective increase of wnt4 transcripts in the presence of COG4 ^p.G516R . Moreover, overexpression of wnt4 mRNA phenocopies these developmental defects. LGK974, an inhibitor of Wnt signaling, corrects the shortened body length at low concentrations but amplifies it at slightly higher concentrations. WNT4 and the non-canonical Wnt signaling component phospho-JNK are also elevated in cultured SWS-derived fibroblasts. Similar results from SWS cell lines and zebrafish point to altered non-canonical Wnt signaling as one possible mechanism underlying SWS pathology.

Prenatal case of Simpson-Golabi-Behmel syndrome with a de novo 370Kb-sized microdeletion of Xq26.2 compassing partial GPC3 gene and review

BACKGROUND

Simpson-Golabi-Behmel syndrome type 1 (SGBS1) is a rare X-linked recessive disorder characterized by pre- and postnatal overgrowth and a broad spectrum of anomalies including craniofacial dysmorphism, heart defects, renal, and genital anomalies. Due to the ultrasound findings are not pathognomonic for this syndrome, most clinical diagnosis of SGBS1 are made postnatally.

METHODS

A pregnant woman with abnormal prenatal sonographic findings was advised to perform molecular diagnosis. Single nucleotide polymorphism array (SNP array) was performed in the fetus, and the result was validated with multiplex ligation-dependent probe amplification (MLPA) and real-time quantitative PCR (qPCR).

RESULTS

The prenatal sonographic presented with increased nuchal translucency at 13 gestational weeks, and later at 21 weeks with cleft lip and palate, heart defect, increased amniotic fluid index and over growth. A de novo 370Kb-deletion covering the 5'-UTR and exon 1 of GPC3 gene was detected in the fetus by SNP array, which was subsequently confirmed by MLPA and qPCR.

CONCLUSION

The de novo 370Kb hemizygous deletion of 5'-UTR and exon 1 of GPC3 results in the SGBS1 of this Chinese family. Combination of ultrasound and genetics tests helped us effectively to diagnose the prenatal cases of SGBS1. Our findings also enlarge the spectrum of mutations in GPC3 gene.

Simpson-Golabi-Behmel syndrome: One family, same mutation, different outcome

Simpson-Golabi-Behmel syndrome (SGBS) is a rare X-linked condition characterized by pre and postnatal overgrowth with visceral and skeletal abnormalities. The syndrome is caused mainly by mutations in the X-linked gene GPC3. Clinical presentation of SGBS in affected males is well defined, but there is a lack of knowledge about affected females, with very few reported cases. In total, eight female carriers with clinical expression of SGBS have been reported to date. In the present report, we describe the ninth patient and her family history. The interesting features of our female patient are the Wilms' tumor and the transfontanelar ultrasound findings. The patient's older sister, carrier of the same mutation, has minor facial dysmorphisms but no congenital anomalies and so far, no further clinical findings, as well as her mother and grandmother. There is a lesson to be learned from these rare cases, namely that SGBS may have a significant clinical expression in females, and therefore, screening should be considered in all patients with SGBS regardless of the sex or phenotypic severity.

DNA methylation during human adipogenesis and the impact of fructose

BACKGROUND

Increased adipogenesis and altered adipocyte function contribute to the development of obesity and associated comorbidities. Fructose modified adipocyte metabolism compared to glucose, but the regulatory mechanisms and consequences for obesity are unknown. Genome-wide methylation and global transcriptomics in SGBS pre-adipocytes exposed to 0, 2.5, 5, and 10 mM fructose, added to a 5-mM glucose-containing medium, were analyzed at 0, 24, 48, 96, 192, and 384 h following the induction of adipogenesis.

RESULTS

Time-dependent changes in DNA methylation compared to baseline (0 h) occurred during the final maturation of adipocytes, between 192 and 384 h. Larger percentages (0.1% at 192 h, 3.2% at 384 h) of differentially methylated regions (DMRs) were found in adipocytes differentiated in the glucose-containing control media compared to adipocytes differentiated in fructose-supplemented media (0.0006% for 10 mM, 0.001% for 5 mM, and 0.005% for 2.5 mM at 384 h). A total of 1437 DMRs were identified in 5237 differentially expressed genes at 384 h post-induction in glucose-containing (5 mM) control media. The majority of them inversely correlated with the gene expression, but 666 regions were positively correlated to the gene expression.

CONCLUSIONS

Our studies demonstrate that DNA methylation regulates or marks the transformation of morphologically differentiating adipocytes (seen at 192 h), to the more mature and metabolically robust adipocytes (as seen at 384 h) in a genome-wide manner. Lower (2.5 mM) concentrations of fructose have the most robust effects on methylation compared to higher concentrations (5 and 10 mM), suggesting that fructose may be playing a signaling/regulatory role at lower concentrations of fructose and as a substrate at higher concentrations.

A systematic review of monogenic etiologies of nonimmune hydrops fetalis

Hydrops Fetalis (HF), accumulation of fluid in two or more fetal compartments, is life-threatening to the fetus. Genetic etiologies include many chromosomal and monogenic disorders. Despite this, the clinical workup typically evaluates limited genetic targets. To support broader molecular testing of pregnancies with HF, we cataloged the spectrum of monogenic disorders associated with nonimmune hydrops fetalis (NIHF).

We performed a systematic literature review under PROSPERO tag CRD42018099495 of cases reporting NIHF meeting strict phenotypic criteria and well-defined genetic diagnosis. We ranked the evidence per gene based on number of reported cases, phenotype and molecular/biochemical diagnosis.

We identified 131 genes with strong evidence for an association with NIHF and 46 genes with emerging evidence spanning the spectrum of multisystem syndromes, cardiac disorders, hematologic disorders, and metabolic disorders. Several genes previously implicated with NIHF did not have any reported cases in the literature with both fetal hydrops and molecular diagnosis. Many genes with strong evidence for association with NIHF would not be detected using current sequencing panels.

Nonimmune HF has many possible monogenic etiologies, several with treatment implications, but current diagnostic approaches are not exhaustive. Studies are needed to assess if broad sequencing approaches like whole exome sequencing are useful in clinical management of HF.

Astrocytic Factors Controlling Synaptogenesis: A Team Play

Astrocytes are essential players in brain circuit development and homeostasis, controlling many aspects of synapse formation, function, plasticity and elimination both during development and adulthood. Accordingly, alterations in astrocyte morphogenesis and physiology may severely affect proper brain development, causing neurological or neuropsychiatric conditions. Recent findings revealed a huge astrocyte heterogeneity among different brain areas, which is likely at the foundation of the different synaptogenic potential of these cells in selected brain regions. This review highlights recent findings on novel mechanisms that regulate astrocyte-mediated synaptogenesis during development, and the control of synapse number in the critical period or upon synaptic plasticity.

Genetics and signaling mechanisms of orofacial clefts

Craniofacial development involves several complex tissue movements including several fusion processes to form the frontonasal and maxillary structures, including the upper lip and palate. Each of these movements are controlled by many different factors that are tightly regulated by several integral morphogenetic signaling pathways. Subject to both genetic and environmental influences, interruption at nearly any stage can disrupt lip, nasal, or palate fusion and result in a cleft. Here, we discuss many of the genetic risk factors that may contribute to the presentation of orofacial clefts in patients, and several of the key signaling pathways and underlying cellular mechanisms that control lip and palate formation, as identified primarily through investigating equivalent processes in animal models, are examined.

Proteoglycans in Obesity-Associated Metabolic Dysfunction and Meta-Inflammation

Proteoglycans are a specific subset of glycoproteins found at the cell surface and in the extracellular matrix, where they interact with a plethora of proteins involved in metabolic homeostasis and meta-inflammation. Over the last decade, new insights have emerged on the mechanism and biological significance of these interactions in the context of diet-induced disorders such as obesity and type-2 diabetes. Complications of energy metabolism drive most diet-induced metabolic disorders, which results in low-grade chronic inflammation, thereby affecting proper function of many vital organs involved in energy homeostasis, such as the brain, liver, kidney, heart and adipose tissue. Here, we discuss how heparan, chondroitin and keratan sulfate proteoglycans modulate obesity-induced metabolic dysfunction and low-grade inflammation that impact the initiation and progression of obesity-associated morbidities.

Overgrowth Syndromes-Evaluation, Diagnosis, and Management

Abnormally excessive growth results from perturbation of a complex interplay of genetic, epigenetic, and hormonal factors that orchestrate human growth. Overgrowth syndromes generally present with inherent health concerns and, in some instances, an increased risk of tumor predisposition that necessitate prompt diagnosis and appropriate referral. In this review, we introduce some of the more common overgrowth syndromes, along with their molecular mechanisms, diagnostics, and medical complications for improved recognition and management of patients affected with these disorders.

Congenital malformation syndromes associated with peripheral neuroblastic tumors: A systematic review

Malformation syndromes with predisposition to peripheral neuroblastic tumors (pNT), including neuroblastoma, ganglioneuroblastoma, and ganglioneuroma, may provide clues to critical mutations influencing pNT development. Our objective was to identify and characterize features of pNT associated with specific malformation syndromes. A systematic review of the literature was performed using MEDLINE, Scopus, and Web of Science. We identified 154 of 1014 papers that met eligibility, comprising 207 cases. The patient's age, tumor histology, and frequency of multiple primary tumors varied by malformation syndrome. Genomic studies and systematized reporting are necessary to elucidate cancer risk and the distinct clinical and biological pNT patterns within syndromes.

Simpson-Golabi-Behmel syndrome type 1 with subclinical hypothyroidism: A case report

RATIONALE

Simpson-Golabi-Behmel syndrome type 1 (SGBS1) is caused by mutations in GPC3 or in both GPC3 and GPC4. Physical manifestations of SGBS1 include fetal overgrowth and macrostomia, macroglossia. Subclinical hypothyroidism has never been reported in SGBS1 cases.

PATIENT CONCERNS

An 8-days-old boy was referred to our hospital with persistent hypoglycemia and special facies. And the infant showed elevated levels of thyroid-stimulating hormone (TSH). Free T4 and free T3 were normal.

DIAGNOSES

Definitive diagnosis of SGBS1 depends on clinical features and genetic testing. A nonsense mutation (c.1515C > A, p. Cys505*) was tested by whole-exome sequencing.

INTERVENTIONS

Normal blood glucose levels were maintained with glucose infusions. Levothyroxine was given to the patient for treating subclinical hypothyroidism.

OUTCOMES

The parents decided to abandon the treatment of the patient. We learned that the patient died of a lung infection by a telephone follow-up.

LESSONS

Subclinical hypothyroidism could be added to the known clinical manifestations of SGBS1.

Whole exome sequencing aids the diagnosis of Simpson-Golabi-Behmel syndrome in two male fetuses

Objective

To diagnose and explore the genetic aetiology of Simpson–Golabi–Behmel syndrome type 1 (SGBS1) in two male fetuses.

Methods

Prenatal ultrasound scans and further genetic analysis using karyotype analysis, chromosomal microarray analysis, whole exome sequencing (WES) and Sanger sequencing were conducted.

Results

Prenatal ultrasound scans of two fetuses showed multiple congenital anomalies and hydramnios. Subsequent to termination of the pregnancies, a novel nonsense variant (c.892G>T, p.E298*) in the glypican 3 (GPC3) gene of the two fetuses was identified by WES and further confirmed by Sanger sequencing. The two fetuses were diagnosed with SGBS1. The mother was heterozygous for the c.892G>T variant.

Conclusion

This study describes the prenatal sonographic features of SGBS1, emphasizes the role of WES in the diagnosis of SGBS1 and expands the known mutation spectrum of the GPC3 gene.

Overgrowth syndromes - clinical and molecular aspects and tumour risk

Overgrowth syndromes are a heterogeneous group of rare disorders characterized by generalized or segmental excessive growth commonly associated with additional features, such as visceromegaly, macrocephaly and a large range of various symptoms. These syndromes are caused by either genetic or epigenetic anomalies affecting factors involved in cell proliferation and/or the regulation of epigenetic markers. Some of these conditions are associated with neurological anomalies, such as cognitive impairment or autism. Overgrowth syndromes are frequently associated with an increased risk of cancer (embryonic tumours during infancy or carcinomas during adulthood), but with a highly variable prevalence. Given this risk, syndrome-specific tumour screening protocols have recently been established for some of these conditions. Certain specific clinical traits make it possible to discriminate between different syndromes and orient molecular explorations to determine which molecular tests to conduct, despite the syndromes having overlapping clinical features. Recent advances in molecular techniques using next-generation sequencing approaches have increased the number of patients with an identified molecular defect (especially patients with segmental overgrowth). This Review discusses the clinical and molecular diagnosis, tumour risk and recommendations for tumour screening for the most prevalent generalized and segmental overgrowth syndromes.

Immunotherapeutic Targeting of GPC3 in Pediatric Solid Embryonal Tumors

Glypican 3 (GPC3) is a heparan sulfate proteoglycan and cell surface oncofetal protein which is highly expressed on a variety of pediatric solid embryonal tumors including the majority of hepatoblastomas, Wilms tumors, rhabdoid tumors, certain germ cell tumor subtypes, and a minority of rhabdomyosarcomas. Via both its core protein and heparan sulfate side chains, GPC3 activates the canonical Wnt/β-catenin pathway, which is frequently overexpressed in these malignancies. Loss of function mutations in GPC3 lead to Simpson-Golabi-Behmel Syndrome, an X-linked overgrowth condition with a predisposition to GPC3-expressing cancers including hepatoblastoma and Wilms tumor. There are several immunotherapeutic approaches to targeting GPC3, including vaccines, monoclonal antibodies, antibody-drug conjugates, bispecific antibodies, cytolytic T lymphocytes, and CAR T cells. These therapies offer a potentially novel means to target these pediatric solid embryonal tumors. A key pediatric-specific consideration of GPC3-targeted immunotherapeutics is that GPC3 can be physiologically expressed in normal tissues during the first year of life, particularly in the liver and kidney. In summary, this article reviews the current evidence for targeting childhood cancers with GPC3-directed immunotherapies.

CUGC for Simpson-Golabi-Behmel syndrome (SGBS)

NAME OF THE DISEASE (SYNONYMS)

Simpson-Golabi-Behmel syndrome (SGBS). OMIM# OF THE DISEASE: 312870.

NAME OF THE ANALYSED GENES OR DNA/CHROMOSOME SEGMENTS

GPC3. OMIM# OF THE GENE(S): 300037. Review of the analytical and clinical validity as well as of the clinical utility of DNA-based testing for mutations in the GPC3 gene(s) in ⊠ diagnostic, ☐ predictive and ⊠ prenatal settings and for ⊠ risk assessment in relatives.

Ovotesticular Disorder of Sex Development (Ovotestis) in Simpson-Golabi-Behmel Syndrome: Expansion of the Clinical Spectrum

Simpson-Golabi-Behmel syndrome type I (SGBS, OMIM312870), caused by defects of the GPC3 and GPC4 genes on chromosome Xq26, is an X-linked recessive macrosomia/multiple congenital anomaly disorder characterized by somatic overgrowth, coarse facial features, variable congenital anomalies, increased tumor risk, and mild-to-moderate neurodevelopmental anomalies. We report the postmortem findings in 3 second-trimester male siblings with SGBS who displayed ambiguous genitalia (in all 3) and gonadal dysgenesis (ovotestis) (in 1), thus expanding the SGBS spectrum to include these disorders of sex development.

Pseudoacromegaly

Individuals with acromegaloid physical appearance or tall stature may be referred to endocrinologists to exclude growth hormone (GH) excess. While some of these subjects could be healthy individuals with normal variants of growth or physical traits, others will have acromegaly or pituitary gigantism, which are, in general, straightforward diagnoses upon assessment of the GH/IGF-1 axis. However, some patients with physical features resembling acromegaly - usually affecting the face and extremities -, or gigantism - accelerated growth/tall stature - will have no abnormalities in the GH axis. This scenario is termed pseudoacromegaly, and its correct diagnosis can be challenging due to the rarity and variability of these conditions, as well as due to significant overlap in their characteristics. In this review we aim to provide a comprehensive overview of pseudoacromegaly conditions, highlighting their similarities and differences with acromegaly and pituitary gigantism, to aid physicians with the diagnosis of patients with pseudoacromegaly.

Simpson-Golabi-Behmel syndrome in a 39-year-old male patient with suspected acromegaly-A case study

Simpson-Golabi-Behmel syndrome (SGBS) is a rare genetic condition and is inherited in an X-linked recessive manner. The disease is caused by a change in the nucleotide sequence of an X-linked gene encoding glypican 3, a protein belonging to the heparan-sulfate membrane proteoglycan family. SGBS case studies are almost entirely restricted to the pediatric population. Scarce literature describing SGBS course in adults may be due to both the high mortality of SGBS patients in childhood and low rate of SGBS diagnosis in adults. We present a case of a 39-year-old man with an initial diagnosis of acromegaly. Genetic tests revealed a hitherto unreported deletion in the GPC3 gene. SGBS manifestations in our patient included tall stature, dysmorphic features, and central nervous system (CNS) anatomical pathology. MRI of the head visualized abnormalities of median line structures, a feature consistent with SGBS: an unclosed craniopharyngeal canal, a sellar-suprasellar cyst, dysmorphic pituitary gland, and a cyst of the septum pellucidum. Moreover, cardiomyopathy complicated by life-threatening paroxysmal ventricular tachycardia was diagnosed. Although various cardiac anomalies are often found in SGBS, their pathogenesis is unclear and may be multifactorial. We believe that the presented case contributes to a better understanding of SGBS and may help clinicians in introducing prophylaxis and treatment for its comorbidities.

Synchronous occurrence of multiple distinct jaw lesions in Simpson-Golabi-Behmel Syndrome: A case report

Simpson-Golabi-Behmel Syndrome (SGBS) is an X-linked overgrowth syndrome characterized by pre- and post-natal overgrowth, typical facial appearance and multiple visceral, skeletal, and neurological anomalies. There is only few information in the current literature, on clinical and particularly dentofacial findings due to recent identification of the syndrome and its clinical overlap with other overgrowth syndromes. The aim of this case report is to present dentofacial findings in a 16-year-old boy who had been diagnosed with SGBS. Following comprehensive clinical, radiographic and histopathological examinations, six pathologically distinct lesions including odontogenic keratocyst, ameloblastoma, lateral periodontal cyst, dentigerous cyst and mucous retention cyst in both mandible and maxilla were identified. The clinical report is followed by a discussion aimed to clarify unique features of this condition and how practitioners should consider similar cases.

Duplications of GPC3 and GPC4 genes in symptomatic female carriers of Simpson-Golabi-Behmel syndrome type 1

GPC3 and GPC4 are the only two genes in which mutations are known to cause Simpson-Golabi-Behmel syndrome type 1 (SGBS1). The majority of SGBS1 patients have point mutations or deletions in GPC3. Only one SGBS1 family has been reported with duplication of both GPC3 and GPC4. Although clinical presentation of SGBS1 in affected males is well defined, the phenotype in female carriers is less clear. In total, six female carriers with clinical expression of SGBS1 have been reported to date. In this study, we provide description of two families with rare duplications in both GPC3 and GPC4. These imbalances resulted in SGBS1 in males, while female carriers with skewed X-inactivation exhibited significant features of SGBS1 including congenital heart defect, hernias, intellectual disability and coarse facial features. In family 2, a SGBS diagnosis was not considered in the father until after the diagnosis had been first considered and made in the affected daughter. We emphasize on the importance of testing at risk females and careful examination of those who are found to be carriers of SGBS1. We also discuss and provide supportive evidence for the role of skewed X-inactivation in clinical expression of SGBS1 in female carriers.

FTO mediates cell-autonomous effects on adipogenesis and adipocyte lipid content by regulating gene expression via 6mA DNA modifications

SNPs in the first intron of α-ketoglutarate-dependent dioxygenase (FTO) convey effects on adiposity by mechanisms that remain unclear, but appear to include modulation of expression of FTO itself, as well as other genes in cisFTO expression is lower in fibroblasts and iPSC-derived neurons of individuals segregating for FTO obesity risk alleles. We employed in vitro adipogenesis models to investigate the molecular mechanisms by which Fto affects adipocyte development and function. Fto expression was upregulated during adipogenesis, and was required for the maintenance of CEBPB and Cebpd/CEBPD expression in murine and human adipocytes in vitro. Fto knockdown decreased the number of 3T3-L1 cells that differentiated into adipocytes as well as the amount of lipid per mature adipocyte. This effect on adipocyte programming was conveyed, in part, by modulation of CCAAT enhancer binding protein (C/ebp)β-regulated transcription. We found that Fto also affected Cebpd transcription by demethylating DNA N6-methyldeoxyadenosine in the Cebpd promoter. Fto is permissive for adipogenesis and promotes maintenance of lipid content in mature adipocytes by enabling C/ebpβ-driven transcription and expression of Cebpd These findings are consistent with the loss of fat mass in mice segregating for a dominant-negative Fto allele.

Two Consecutive Pregnancies with Simpson-Golabi-Behmel Syndrome Type 1: Case Report and Review of Published Prenatal Cases

Fetal overgrowth and numerous congenital malformations can be detected in every trimester of pregnancy. New technologies in molecular testing, such as chromosomal microarray analysis and next-generation sequencing, continually demonstrate advantages for definitive diagnosis in fetal life. Simpson-Golabi-Behmel (SGB) syndrome is a rare but well-known overgrowth condition that is rarely diagnosed in the prenatal setting. We report 3 cases of SGB syndrome in 2 consecutive pregnancies. In our series, distinctive prenatal sonographic findings led to molecular diagnosis. Exome sequencing from fetal DNA revealed a hemizygous splice site variant in the GPC3 gene: NM_004484.3:c.1166+ 1G>T. The mother is a heterozygous carrier. We also provide an overview of the previously published 57 prenatal cases of SGB syndrome with prevalence estimation of the symptoms to aid prenatal differential diagnosis of fetal overgrowth syndromes.

SGBS cells as a model of human adipocyte browning: A comprehensive comparative study with primary human white subcutaneous adipocytes

The Simpson Golabi Behmel Syndrome (SGBS) pre-adipocyte cell strain is widely considered to be a representative in vitro model of human white pre-adipocytes. A recent study suggested that SGBS adipocytes exhibit an unexpected transient brown phenotype. Here, we comprehensively examined key differences between SGBS adipocytes and primary human white subcutaneous (PHWSC) adipocytes. RNA-Seq analysis revealed that extracellular matrix (ECM)-receptor interaction and metabolic pathways were the top two KEGG pathways significantly enriched in SGBS adipocytes, which included positively enriched mitochondrial respiration and oxidation pathways. Compared to PHWSC adipocytes, SGBS adipocytes showed not only greater induction of adipogenic gene expression during differentiation but also increased levels of UCP1 mRNA and protein expression. Functionally, SGBS adipocytes displayed higher ISO-induced basal leak respiration and overall oxygen consumption rate, along with increased triglyceride accumulation and insulin-stimulated glucose uptake. In conclusion, we confirmed that SGBS adipocytes, which are considered of white adipose tissue origin can shift towards a brown/beige adipocyte phenotype. These differences indicate SGBS cells may help to identify mechanisms leading to browning, and inform our understanding for the use of SGBS vis-à-vis primary human subcutaneous adipocytes as a human white adipocyte model, guiding the selection of appropriate cell models in future metabolic research.

Perinatal Case of Fatal Simpson-Golabi-Behmel Syndrome with Hyperplasia of Seminiferous Tubules

Patient: Male, newborn

Final Diagnosis: Simpson-Golabi-Behmel syndrome

Symptoms: Dyspnea

Medication: —

Clinical Procedure: —

Specialty: Pediatrics and Neonatology

A clinical review on megalencephaly: A large brain as a possible sign of cerebral impairment

Megalencephaly and macrocephaly present with a head circumference measurement 2 standard deviations above the age-related mean. However, even if pathologic events resulting in both megalencephaly and macrocephaly may coexist, a distinction between these two entities is appropriate, as they represent clinical expression of different disorders with a different approach in clinical work-up, overall prognosis, and treatment. Megalencephaly defines an increased growth of cerebral structures related to dysfunctional anomalies during the various steps of brain development in the neuronal proliferation and/or migration phases or as a consequence of postnatal abnormal events. The disorders associated with megalencephaly are classically defined into 3 groups: idiopathic or benign, metabolic, and anatomic. In this article, we seek to underline the clinical aspect of megalencephaly, emphasizing the main disorders that manifest with this anomaly in an attempt to properly categorize these disorders within the megalencephaly group.

First reported case of Simpson-Golabi-Behmel syndrome in a female fetus diagnosed prenatally with chromosomal microarray

Simpson–Golabi–Behmel syndrome (SGBS) is a rare X‐linked syndrome. Female carriers may have mild manifestations. Macrosomia, polyhydramnios, and kidney and urinary tract anomalies are common findings in male fetuses. We present the first case of a severely affected female fetus with stigmata of SGBS and a deletion involving the GPC3 gene.