TSC2 Research Articles

Sclerotic Bone Lesions as a Clue in the Diagnosis of Three Generations of Tuberous Sclerosis Complex: Case Report and Review of Literature

Tuberous sclerosis complex (TSC) is an autosomal dominant genetic disorder that can involve multiple organ systems. Diagnosis is based on independent clinical diagnostic criteria and genetic diagnostic criteria (pathogenic variants on TSC1 and TSC2 genes). To make a definitive diagnosis can be especially difficult in oligosymptomatic or asymptomatic patients and in those patients with genetic variants of uncertain significance (VUS). Early diagnosis and lifelong surveillance are paramount to avoid morbidity and potentially life-threatening complications. To increase diagnostic sensibility, less known manifestations of TSC can be helpful. Herein we show a case in which SBLs were used as a diagnostic clue to help diagnose three generations of oligosymptomatic TSC carrying a VUS in TSC1. SBLs are commonly detected in imaging studies of patients with TSC and have been recently included as a minor clinical diagnostic criterion. Clinicians and radiologists should be aware of their significance as they can be mistaken with osteoblastic metastases.

An Integral Approach to the Molecular Diagnosis of Tuberous Sclerosis Complex: The Role of Mosaicism and Splicing Variants

Tuberous sclerosis complex (TSC) is an autosomal dominant genetic disorder characterized by the presence of hamartomas in multiple organs. At the molecular level, the disease is caused by pathogenic variants in the TSC1 and TSC2 genes, and only 10% to 25% of clinically diagnosed patients remain negative after multiplex ligation-dependent probe amplification and exon sequencing of both genes. Here, to improve the molecular diagnosis of TSC, we developed an integral approach that includes multiplex ligation-dependent probe amplification and deep-coverage next-generation sequencing of the entire TSC1 and TSC2 genes, along with an adapted bioinformatic pipeline to detect variants at low allele frequencies (>1%). Using this workflow, the molecular cause was identified in 29 of 42 patients with TSC, describing here, for the first time, 12 novel pathogenic variants in TSC genes. These variants included seven splicing variants, five of which were studied at the cDNA level, determining their effect on splicing. In addition, 8 of the 29 pathogenic variants were detected in mosaicism, including four patients with previous negative study results who presented extremely low mosaic variants (allele frequency, <16%). We demonstrate that this integral approach allows the molecular diagnosis of patients with TSC and improves the conventional one by adapting the technology to the detection of low-frequency mosaics.

Multidisciplinary Outpatient Clinic of Neurocutaneous Diseases: Five-year Experience of a Pediatric Tertiary Hospital in Portugal.

Neurocutaneous syndromes (NCS) are a heterogeneous group of conditions with multiorgan involvement and diverse manifestations, evolving throughout life with significant morbidity. A multidisciplinary approach to NCS patients has been advocated, although a specific model is not yet established. The aim of this study was 1) to describe the organization of the recently created Multidisciplinary Outpatient Clinic of Neurocutaneous Diseases (MOCND) at a Portuguese pediatric tertiary hospital; 2) to share our institutional experience focusing on the most common conditions, neurofibromatosis type 1 (NF1) and tuberous sclerosis complex (TSC); 3) to analyze the advantages of a multidisciplinary center and approach in NCS. Retrospective analysis of 281 patients enrolled in the MOCND over the first five years of activity (October 2016 to December 2021), reviewing genetics, family history, clinical features, complications, and therapeutic strategies for NF1 and TSC. The clinic works weekly with a core team of pediatricians and pediatric neurologists supported by other specialties as needed. Of the 281 patients enrolled, 224 (79.7%) had identifiable syndromes such as NF1 (n = 105), TSC (n = 35), hypomelanosis of Ito (n = 11), Sturge-Weber syndrome (n = 5), and others. In NF1 patients, 41.0% had a positive family history, all manifested café-au-lait macules, 38.1% neurofibromas with 45.0% being large plexiform neurofibromas. Sixteen were under treatment with selumetinib. Genetic testing was performed in 82.9% of TSC patients with pathogenic variants found in TSC2 gene in 72.4% patients (82.7% if considered contiguous gene syndrome). Family history was positive in 31.4%. All TSC patients presented hypomelanotic macules and fulfilled diagnostic criteria. Fourteen patients were being treated with mTOR inhibitors. Offering a systematic and multidisciplinary approach to NCS patients enables timely diagnosis, promotes a structured follow-up, and encourages discussion to outline management plans for optimal care to every patient, with significant impact on the quality of life of patients and families.

Reversal of memory and autism-related phenotypes in Tsc2+/- mice via inhibition of Nlgn1.

Tuberous sclerosis complex (TSC) is a rare monogenic disorder co-diagnosed with high rates of autism and is caused by loss of function mutations in the TSC1 or TSC2 genes. A key pathway hyperactivated in TSC is the mammalian/mechanistic target of rapamycin complex 1 (mTORC1), which regulates cap-dependent mRNA translation. We previously demonstrated that exaggerated cap-dependent translation leads to autism-related phenotypes and increased mRNA translation and protein expression of Neuroligin 1 (Nlgn1) in mice. Inhibition of Nlgn1 expression reversed social behavior deficits in mice with increased cap-dependent translation. Herein, we report elevated translation of Nlgn1 mRNA and an increase in its protein expression. Genetic or pharmacological inhibition of Nlgn1 expression in Tsc2 +/- mice rescued impaired hippocampal mGluR-LTD, contextual discrimination and social behavior deficits in Tsc2 +/- mice, without correcting mTORC1 hyperactivation. Thus, we demonstrate that reduction of Nlgn1 expression in Tsc2 +/- mice is a new therapeutic strategy for TSC and potentially other neurodevelopmental disorders.

Proteomic analysis of murine Tsc1-deficient neural stem progenitor cells

Tuberous sclerosis complex (TSC) is a rare, multisystem genetic disorder that leads to the development of benign tumors in multiple organs and neurological symptoms. TSC clinical manifestations show a great heterogenicity, with most patients presenting severe neuropsychiatric and neurological disorders. TSC is caused by loss-of-function mutations in either TSC1 or TSC2 genes, leading to overexpression of the mechanistic target of rapamycin (mTOR) and, consequently, abnormal cellular growth, proliferation and differentiation as well as to cell migration defects. Beside the growing interest, TSC remains a disorder poorly understood, with limited perspectives in the field of therapeutic strategies. Here we used murine postnatal subventricular zone (SVZ) neural stem progenitor cells (NSPCs) deficient of Tsc1 gene as a TSC model to unravel novel molecular aspects of the pathophysiology of this disease. 2D-DIGE-based proteomic analysis detected 55 differently represented spots in Tsc1-deficient cells, compared to wild-type counterparts, which were associated with 36 protein entries after corresponding trypsinolysis and nanoLC-ESI-Q-Orbitrap-MS/MS analysis. Proteomic results were validated using various experimental approaches. Bioinformatics associated differently represented proteins with oxidative stress and redox pathways, methylglyoxal biosynthesis, myelin sheath, protein S-nitrosylation and carbohydrate metabolism. Because most of these cellular pathways have already been linked to TSC features, these results were useful to clarify some molecular aspects of TSC etiopathogenesis and suggested novel promising therapeutic protein targets. SignificanceTuberous Sclerosis Complex (TSC) is a multisystemic disorder caused by inactivating mutations of TSC1 or TSC2 genes, which induce overactivation of the mTOR component. The molecular mechanisms underlying the pathogenesis of TSC remain unclear, probably due to complexity of mTOR signaling network. To have a picture of protein abundance changes occurring in TSC disorder, murine postnatal subventricular zone (SVZ) neural stem progenitor cells (NSPCs) deficient of Tsc1 gene were used as a model of disease. Thus, Tsc1-deficient SVZ NSPCs and wild-type cells were comparatively evaluated by proteomics. This analysis evidenced changes in the abundance of proteins involved in oxidative/nitrosative stress, cytoskeleton remodelling, neurotransmission, neurogenesis and carbohydrate metabolism. These proteins might clarify novel molecular aspects of TSC etiopathogenesis and constitute putative molecular targets for novel therapeutic management of TSC-related disorders.

Specific Features of Focal Cortical Dysplasia in Tuberous Sclerosis Complex.

Patients with tuberous sclerosis complex present with cognitive, behavioral, and psychiatric impairments, such as intellectual disabilities, autism spectrum disorders, and drug-resistant epilepsy. It has been shown that these disorders are associated with the presence of cortical tubers. Tuberous sclerosis complex results from inactivating mutations in the TSC1 or TSC2 genes, resulting in hyperactivation of the mTOR signaling pathway, which regulates cell growth, proliferation, survival, and autophagy. TSC1 and TSC2 are classified as tumor suppressor genes and function according to Knudson's two-hit hypothesis, which requires both alleles to be damaged for tumor formation. However, a second-hit mutation is a rare event in cortical tubers. This suggests that the molecular mechanism of cortical tuber formation may be more complicated and requires further research. This review highlights the issues of molecular genetics and genotype-phenotype correlations, considers histopathological characteristics and the mechanism of morphogenesis of cortical tubers, and also presents data on the relationship between these formations and the development of neurological manifestations, as well as treatment options.

De novo mutation of the TSC2 gene in patient with Tuberous Sclerosis Complex-Associated Neuropsychiatric Disorders (TAND) Phenotype: a case report.

A 17-year-old girl presented with TSC, absence and focal epilepsy, borderline intellectual functioning, organic psychosis, and renal angiomyolipoma. She was emotionally unstable and preoccupied with irrelevant fears. In the physical examination, we found multiple hypomelanotic maculae, angiofibroma, and a shagreen patch. The intellectual assessment result with the Wechsler Adult Intelligence Scale at 17 was borderline intellectual functioning. Brain MRI showed cortical and subcortical tubers in the parietal and occipital lobes. Whole-exome sequencing was conducted, and the result was a missense mutation in exon 39 of the TSC2 gene [NM_000548.5:c.5024C>T (NP_000539.2:p.Pro1675Leu)]. The Sanger sequencing of the patient's parents revealed no mutations in the TSC2 gene, confirming the patient's de novo mutation. The patient was given several antiepileptic and antipsychotic drugs. Neuropsychiatric manifestation is a common phenotype in the TSC variant, and psychosis is one of the rare TAND symptoms in children. The neuropsychiatric phenotype and genotype in TSC patients are rarely reported and evaluated. We reported a female child with epilepsy, borderline intellectual functioning, and organic psychosis associated with a de novo mutation of the TSC2 gene. Organic psychosis is a rare symptom of TAND which also manifested in our patient.

Detecting Low-Variant Allele Frequency Mosaic Pathogenic Variants of NF1, TSC2, and AKT3 Genes from Blood in Patients with Neurodevelopmental Disorders

Growing evidence indicates that early and late postzygotic mosaicism can cause neurodevelopmental disorders (NDDs), but detection of low variant allele frequency (VAF) mosaic variants from blood remains a challenge. Data of 2162 patients with NDDs who underwent conventional genetic tests were reviewed and a deep sequencing was performed using a specifically designed mosaic next-generation sequencing (NGS) panel in the patients with negative genetic test results. Forty-four patents with neurocutaneous syndrome, malformation of cortical development, or nonlesional epileptic encephalopathies were included. In total, mosaic variants were detected from blood in 1.2% (25/2162) of the patients. Using conventional NGS panels, 22 mosaic variants (VAF, 8.8% to 29.8%) were identified in 18 different genes. Using a specifically designed mosaicism NGS panel, three mosaic variants of the NF1, TSC2, and AKT3 genes were identified (VAF, 2.0% to 11.2%). Mosaic variants were found frequently in the patients who had neurocutaneous syndrome (2/7, 28.6%), whereas only one or no mosaic variant was detected for patients who had malformations of cortical development (1/20, 5%) or nonlesional epileptic encephalopathies (0%, 0/17). In summary, mosaic variants that contribute to the spectrum of NDDs can be detected from blood via conventional NGS and specifically designed mosaicism NGS panels, and detection of mosaic variants using blood will increase diagnostic yield.

The TSC2 c.2742+5G>A variant causes variable splicing changes and clinical manifestations in a family with tuberous sclerosis complex.

Tuberous sclerosis complex (TSC) is a genetic, variably expressed, multisystem disease characterized by benign tumors. It is caused by pathogenic variants of the TSC complex subunit 1 gene (TSC1) and the TSC complex subunit 2 gene (TSC2). Genetic testing allows for early diagnosis, genetic counseling, and improved outcomes, but it did not identify a pathogenic variant in up to 25% of all TSC patients. This study aimed to identify the disease-causing variant in a Han-Chinese family with TSC. A six-member, three-generation Han-Chinese family with TSC and three unrelated healthy women were recruited. A comprehensive medical examination, a 3-year follow-up, whole exome sequencing, Sanger sequencing, and segregation analysis were performed in the family. The splicing analysis results obtained from six in silico tools, minigene assay, and patients' lymphocyte messenger RNA were compared, and quantitative reverse transcription PCR was used to confirm the pathogenicity of the variant. Two affected family members had variable clinical manifestations including a rare bilateral cerebellar ataxia symptom. The 3-year follow-up results suggest the effects of a combined treatment of anti-epilepsy drugs and sirolimus for TSC-related epilepsy and cognitive deficits. Whole exome sequencing, Sanger sequencing, segregation analysis, splicing analysis, and quantitative reverse transcription PCR identified the TSC2 gene c.2742+5G>A variant as the genetic cause. This variant inactivated the donor splice site, a cryptic non-canonical splice site was used for different splicing changes in two affected subjects, and the resulting mutant messenger RNA may be degraded by nonsense-mediated decay. The defects of in silico tools and minigene assay in predicting cryptic splice sites were suggested. This study identified a TSC2 c.2742+5G>A variant as the genetic cause of a Han-Chinese family with TSC and first confirmed its pathogenicity. These findings expand the phenotypic and genetic spectrum of TSC and may contribute to its diagnosis and treatment, as well as a better understanding of the splicing mechanism.

Abstract LB288: Biomarker analysis from AMPECT correlating response to nab-sirolimus with TSC1 and TSC2 inactivating alterations

Abstract nab-Sirolimus is an mTOR inhibitor (mTORi) approved in the US for the treatment of adult patients with locally advanced, unresectable, or metastatic malignant perivascular epithelioid cell tumor (PEComa) based on clinical efficacy and safety data from the phase 2, multicenter, open-label AMPECT trial (NCT02494570). TSC1 and TSC2 are tumor suppressor genes and key upstream regulators of mTOR complex 1 (mTORC1); inactivating alterations (loss-of-function mutations or deletions) in these genes lead to mTORC1 hyperactivation, which may contribute to tumor formation. Phosphorylation of S6 ribosomal protein (pS6) is a reliable surrogate for mTORC1 activity. Here we present the results of an exploratory biomarker analysis performed on samples from patients enrolled in the AMPECT study. Targeted exome next-generation sequencing (NGS) using a 500-gene OncoPanel test (Center for Advanced Molecular Diagnostics, Brigham and Women’s Hospital, Boston, MA) assessed mutations, copy number changes, and translocation events. pS6 was assessed by immunohistochemistry (IHC). Twenty-five patients had tissue sufficient for NGS, 56% (14/25) had either TSC1 (N=5, 20%) or TSC2 (N=9, 36%) mutations: TSC1, 1 frameshift, 2 splice site, 1 missense, and 1 nonsense mutation; TSC2, 1 nonsense, 7 frameshift, and 1 homozygous deletion. In this dataset, TSC1 and TSC2 inactivating alterations were mutually exclusive. Patients with TSC1 or TSC2 inactivating alterations achieved a clinically meaningful benefit: 64.3% (9/14) objective overall responses (including complete and partial responses) and median (95% CI) duration of response (DOR) of 45.7 (5.6, not reached [NR]) months, progression-free survival (PFS) of 41.2 (5.5, NR) months, and overall survival (OS) of NR (31.6, NR) months. Mutations in TP53, RB1, and ATRX were also common (48%, 24%, and 20%, respectively). Of tissue samples evaluable for IHC (N=25), responses occurred in 58.8% (10 of 17) of patients with pS6 positive tumors versus 0% (0 of 8) with pS6 negative tumors; absent pS6 staining was negatively associated with response to nab-sirolimus (P=0.008, Fisher’s exact). Median DOR for pS6 positive responders was 39.7 (5.6, NR) months. In pS6 positive vs pS6 negative patients, the median PFS was 24.4 (2.8, 53.1) vs 5.5 (2.8, NR) months, and OS was 53.1 (18.0, NR) vs 37.0 (16.6, NR) months. A variety of pathogenic inactivating alterations were observed in TSC1 and TSC2 genes, though TSC2 mutations were most commonly frameshift mutations; no recurring mutations were observed. A tumor-agnostic study (PRECISION 1: NCT05103358) is now recruiting patients with pathogenic inactivating TSC1 or TSC2 alterations to further examine these biomarker findings. Citation Format: Lee D. Cranmer, Andrew J. Wagner, Vinod Ravi, Richard F. Riedel, Kristen N. Ganjoo, Brian A. Van Tine, Rashmi Chugh, Erlinda M. Gordon, David J. Kwiatkowski, Jason L. Hornick, Heng Du, Li Ding, Anita N. Schmid, Willis H. Navarro, Loretta M. Itri, Mark A. Dickson. Biomarker analysis from AMPECT correlating response to nab-sirolimus with TSC1 and TSC2 inactivating alterations [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr LB288.

Abstract 6021: Genetic and epigenetic features OF KMT2D, CREBBP, ATM, TSC2 and GNAS in uterine leyomiosarcomas

Abstract Background: Uterine leiomyosarcoma (LMS) comprises 60% to 70% of the uterine sarcoma (US). These tumors present high rates of recurrence and metastasis, and the patients’ survival rates are very low (20% in five years). It is known that somatic mutations and modifications in the DNA methylation levels are associated with several types of neoplasms. Previously, our group identified missense and loss of function mutations in KMT2D, CREBBP, ATM, TSC2, and GNAS, using a genetic screening method in LMS samples. Based on these results, we decided to investigate whether a genetic and epigenetic crosstalk could help to understand the biological processes involved in the LMS origin, development, and pathogenesis. The present study aimed to evaluate the KMT2D, CREBBP, ATM, TSC2 and GNAS gene expression profile in LMS cell line, and their methylation levels in formalin-fixed and paraffin-embedded (FFPE) patients´ samples. Methods: We selected 15 LMS - FFPE samples obtained via surgical procedures performed between 2012 and 2019 at the Instituto do Cancer do Estado de São Paulo (ICESP). Genomic DNA was extracted using the QIAamp DNA FFPE Tissue Kit and we evaluated methylation levels using the Illumina Infinium Methylation EPIC BeadChip system 850k, including samples treated with bisulfite-treated DNA. Leiomyoma (LM) (THESCs CRL-4003) and LMS (SK-UT-1) cell lines were cultivated for gene expression analysis. Cells were growth for 24, 48, 72, and 96 hours, and the total RNA was extracted by TRIzol. High-Capacity cDNA Reverse Transcription Kit was used for cDNA synthesis and for gene expression evaluation, real-time PCR reactions were performed using TaqMan Universal PCR Master Mix and inventoried TaqMan probes. Results: KMT2D and TSC2 showed increased expression in LMS compared to LM (cut-off ≤ -2 and ≥ 2 for down and upregulation, respectively), with higher expression in 24 hours of KMT2D [Fold Regulation (FR): 2.77] and TSC2 (FR: 2.58). In contrast, CREBBP was downregulated, with lowest expression in 72 hours (FR: -6.57). ATM was upregulated at 24, 48 with higher expression in 72 hours (FR: 2.32), and GNAS was downregulated, with lowest expression in 96 hours (FR: -4.31). Moreover, the methylation analyzes showed an expressive hypomethylation in LMS samples, compared to myometrium, for KMT2D (β value: 0.45; p= 0.004); CREBBP (β value: 0.51 p &amp;lt; 0.0001); ATM (β value: 0.47 p &amp;lt; 0.0001); TSC2 (β value: 0.53 p &amp;lt; 0.0001) and GNAS (β value: 0.41 p &amp;lt; 0.0001). In conclusion, our study showed that potentially pathogenic mutations may be associated with an aberrant hypomethylation profile, as well as increased expression of KMT2D, TSC2, ATM and loss expression of CREBBP and GNAS in LMS. The interconnection of these genetic and epigenetic events is essential for understanding the complex biology of these tumors, in addition to enabling identification of biomarkers. Citation Format: Laura G. dos Anjos, Daniela Bizinelli, Katia C. Carvalho. Genetic and epigenetic features OF KMT2D, CREBBP, ATM, TSC2 and GNAS in uterine leyomiosarcomas [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6021.

Modulation ofAutophagy and mTOR signalling pathway genes in respiratory epithelium by respiratory syncytial virus (RSV) in children suffering from acute lower respiratory tract infections.

The study was planned to carry out the molecular characterization of the Respiratory Syncytial Virus (RSV) circulating strains and to elucidate the gene expression of autophagy and mTOR signalling pathways in children with acute lower respiratory tract infection (ALRTI). Nasopharyngeal aspirate (NPA) samples (n=145) from children suffering from ALRTI were subjected to the detection of RSV. Of them, 31 RSV positive strains were subjected for sequencing. Semi-quantitative gene expression analysis for mTOR signalling and autophagy pathway genes was performed in respiratory tract epithelial cells using 25 RSV positive cases, and 10 age and sex matched healthy control subjects. Five representative genes were selected for each pathway and subjected to SYBR green real-time polymerase chain reaction (PCR). RSV was positive in 69 (47.6%) samples and the representative (n=31) RSV strains belonged to RSV-A. Thirty-one strains of RSV-A on phylogenetic analysis clustered with the novel ON1 genotype having 72bp nucleotide duplicationby targeting the ecto-domain portion of the G gene. Further, the stains belonged to lineage 1 (51.6%), followed by lineage 3 (29%) and lineage 2 (19.4%). Autophagy gene expression analysis revealed significant upregulation in NPC1 and ATG3 autophagy genes. mTOR, AKT1, and TSC1 genes of the mTOR pathway were significantly down-regulated in RSV positive patients. Thus, RSV infection inducing autophagy pathway genes (NPC1 and ATG3) and suppressing mTOR signalling pathway genes (AKT1, mTOR, and TSC1) to possibly evade the host immune system through dysregulating these pathways for its way of survival within the host. This article is protected by copyright. All rights reserved.

Tsc2 mutation rather than Tsc1 mutation dominantly causes a social deficit in a mouse model of tuberous sclerosis complex

BackgroundTuberous sclerosis complex (TSC) is an autosomal dominant disorder that is associated with neurological symptoms, including autism spectrum disorder. Tuberous sclerosis complex is caused by pathogenic germline mutations of either the TSC1 or TSC2 gene, but somatic mutations were identified in both genes, and the combined effects of TSC1 and TSC2 mutations have been unknown.MethodsThe present study investigated social behaviors by the social interaction test and three-chambered sociability tests, effects of rapamycin treatment, and gene expression profiles with a gene expression microarray in Tsc1 and Tsc2 double heterozygous mutant (TscD+/−) mice.ResultsTscD+/− mice exhibited impairments in social behaviors, and the severity of impairments was similar to Tsc2+/− mice rather than Tsc1+/− mice. Impairments in social behaviors were rescued by rapamycin treatment in all mutant mice. Gene expression profiles in the brain were greatly altered in TscD+/− mice more than in Tsc1+/− and Tsc2+/− mice. The gene expression changes compared with wild type (WT) mice were similar between TscD+/− and Tsc2+/− mice, and the overlapping genes whose expression was altered in mutant mice compared with WT mice were enriched in the neoplasm- and inflammation-related canonical pathways. The “signal transducer and activator of transcription 3, interferon regulatory factor 1, interferon regulatory factor 4, interleukin-2R α chain, and interferon-γ” signaling pathway, which is initiated from signal transducer and activator of transcription 4 and PDZ and LIM domain protein 2, was associated with impairments in social behaviors in all mutant mice.LimitationsIt is unclear whether the signaling pathway also plays a critical role in autism spectrum disorders not caused by Tsc1 and Tsc2 mutations.ConclusionsThese findings suggest that TSC1 and TSC2 double mutations cause autistic behaviors similarly to TSC2 mutations, although significant changes in gene expression were attributable to the double mutations. These findings contribute to the knowledge of genotype–phenotype correlations in TSC and suggest that mutations in both the TSC1 and TSC2 genes act in concert to cause neurological symptoms, including autism spectrum disorder.

Whole-exome sequencing reveals genetic variants in low-risk and high-risk neuroblastoma

This study aimed to investigate the genetic aberrations in neuroblastoma (NB) by comparing high and low-risk NB patients by whole-exome sequencing (WES) and to reveal the heterogeneity and association between somatic variants and clinical features. Seven NB patients with available clinical data were included in the study (4 in the low-risk group and 3 in the high-risk group). WES was performed and somatic variants associated with NB genes in the COSMIC database were selected through bioinformatics pipeline analysis. Variants were determined using the Integrative Genomics Viewer (IGV). Some gene variations were found in both groups, including variations in oncogene and tumor suppressor genes. In general, candidate gene variations were associated with chromatin remodeling complexes, the RAS pathway, cell proliferation, and DNA repair mechanism. Some variations in CSF1R, MSH6, PTPN11, SOX9, RET, TSC1, and DNMT1 genes were detected only in high-risk patients, while EP300, TET2, MYCN, PRDM1, and ARID2 gene variations were detected only in low-risk patients. When high-risk gene variants were compared with the cBioportal cancer genomic database, two common gene variants (ARID1A and NCOR2) were identified. However, when low-risk gene variants were compared with the cBioportal cancer genomic database, no common genes were found. GO/KEGG enrichment analysis was performed to find relevant biological processes and molecular pathways related to gene variants, which will help to decipher the molecular mechanisms of NB tumorigenesis and the phenotypic differences between high-risk and low-risk patients.

Phase 2, multicenter, open-label basket trial of nab-sirolimus for patients with malignant solid tumors harboring pathogenic inactivating alterations in TSC1 or TSC2 genes (PRECISION I).

TPS818 Background: Albumin-bound ( nab)-sirolimus, a novel mTOR inhibitor (mTORi) that utilizes nanoparticle technology to preferentially target tumors, is approved in the US for the treatment of adults with malignant PEComa. In an exploratory analysis of the AMPECT registrational trial of nab-sirolimus in advanced malignant PEComa (NCT02494570), 8/9 (89%) and 1/5 (20%) patients with TSC1 and TSC2 inactivating alterations, respectively, had confirmed response (Wagner, J Clin Oncol. 2021). Importantly, both TSC1 and TSC2 alterations have been observed in patients with various gastrointestinal cancers (Table). Overall, most treatment-related adverse events (TRAEs) in AMPECT were grade 1/2 and manageable for long-term treatment; no grade ≥4 TRAEs occurred. Methods: PRECISION I (NCT05103358) is a phase 2, open-label, multi-institutional basket trial evaluating efficacy and safety of nab-sirolimus in patients with alterations in TSC1 (Arm A) and TSC2 (Arm B). Patients ≥12 years old with malignant solid tumors harboring pathogenic inactivating alterations in TSC1 or TSC2 (confirmed by central review of next generation sequencing reports) who have progressed on standard therapies and are mTORi-naïve are eligible. nab-Sirolimus 100 mg/m2 will be administered weekly as an intravenous infusion over 30 minutes on Days 1 and 8 of each 21-day cycle. The primary endpoint is overall response rate determined by independent review using RECIST v1.1; other endpoints include duration of response, disease control rate, time to response, progression-free survival by independent radiographic review, overall survival, patient-reported quality of life, and safety. Enrollment is ongoing. The most frequent tumor types expected in this tissue-agnostic trial are bladder, hepatobiliary, endometrial, soft tissue sarcoma, ovarian, and esophagogastric based on the prevalence of TSC1 or TSC2 alterations (Table). Clinical trial information: NCT05103358 . [Table: see text]

Late diagnosis of tuberous sclerosis complex in a 40-year-old female presenting with abdominal pain: a case report.

Tuberous sclerosis (TS) is a rare autosomal-dominant neurocutaneous disorder that is characterized by hamartomas affecting a variety of organs, including the brain, heart, kidneys, skin, lungs, and liver. TS can emerge in a wide variety of clinical and phenotypic forms at any age, all with varying degrees of severity, and is brought on by mutations in the tumor suppressor genes TSC1 or TSC2. This case report is about a 40-year-old female with facial angiofibromas and abdominal symptoms who was referred to the radiology department of our hospital for ultrasonography of the abdomen, which revealed echogenic mass lesions/angiomyolipomas in bilateral kidneys. Subsequent contrast-enhanced computed tomography of the abdomen revealed large fat-attenuating mass lesions which were confirmed to be angiomyolipomas. Similarly, noncontrast computed tomography of the head showed multiple calcified nodules/tubers in subependymal, subcortical, and cortical locations of the brain. High-resolution computed tomography of the chest showed multiple cystic lesions in bilateral lungs suggestive of lymphangioleiomyomatosis. The aim of this case report is to highlight the late presentation of tuberous sclerosis complex.

Subependymal Giant Cell Astrocytomas in Tuberous Sclerosis Complex-Current Views on Their Pathogenesis and Management.

Despite the fact that SEGAs are benign, they require well-considered decisions regarding the timing and modality of pharmacological or surgical treatment. In TSC children and adolescents, SEGA is the major cause of mortality and morbidity. Until recently, surgical resection has been the standard therapy for SEGAs but the discovery of the role of the mTOR pathway and the introduction of mTOR inhibitors to clinical practice changed the therapeutic landscape of these tumors. In the current paper, we discuss the pros and cons of mTOR inhibitors and surgical approaches in SEGA treatment. In 2021, the International Tuberous Sclerosis Complex Consensus Group proposed a new integrative strategy for SEGA management. In the following review, we discuss the proposed recommendations and report the results of the literature search for the latest treatment directions.

From the Editor’s Desk...

From the Editor’s Desk...

Tuberous Sclerosis Complex Associated Renal Cell Carcinoma with Leiomyomatous Stroma

This case report is about an unusual subtype of renal cell carcinoma with distinct morphological pattern in a 24-year-old female patient with tuberous sclerosis complex. She presented with pain in the left flank and an Magnetic Resonance Imaging (MRI) upper abdomen showed a solid cystic lesion in the interpolar region of left kidney, measuring 2.8×2.8×2.8 cm. She underwent partial nephrectomy which revealed a solid cystic tumour. Microscopically, the tumour was composed of long branching tubules lined by cells with voluminous clear/ vacuolated cytoplasm. A prominent fibromyomatous stroma was seen focally, separating the tumour into nodular aggregates. Tumour cells were positive for Cytokeratin 7 (CK7) on immunohistochemical study. These features were consistent with renal cell carcinoma with leiomyomatous stroma. Genetic study showed a heterozygous nonsense variation in Tuberous Sclerosis 1 (TSC1), gene, diagnostic of tuberous sclerosis. This report exemplifies the pivotal role pathologists play in the initial identification of certain hereditary cancer syndrome. The distinct morphology and immunohistochemical profile of the tumour is described.

The Efficacy and Safety of Rapamycin in Children with Tuberous Sclerosis: A Cross-sectional Study.

Mutations in TSC1 or TSC2 genes have been proposed as the main causative factors responsible for developing Tuberous Sclerosis Complex (TSC). Given the effect of these two genes on the mTOR pathway, rapamycin has emerged as a novel therapeutic agent. The present study evaluated the effectiveness and safety of rapamycin on the multiple manifestations of TSC. Twenty-three eligible children were enrolled in the present cross-sectional study. They were prescribed rapamycin 1mg tablet twice daily for the first two weeks of treatment and then once daily for at least one year. Periodic evaluations through follow-up visits were performed. Besides, growth and developmental statuses were evaluated. All data, including the number and size of brain tuberomas, size of renal angiomyolipomas, and skin lesions, were gathered and recorded, and then analyzed. During the study period, the mean number of epileptic episodes significantly reduced (p<0.0001), and nine cases were seizure-free at the final visit. The mean number of brain tuberomas decreased from 19.3±11.0 at the initial visit to 11.1±5.6 and 8.2±3.2 in the subsequent visits (p<0.001). The mean size of brain tuberomas similarly decreased from 17.9±18.5 cm at enrollment to 13.7±5.1 cm and 6.9±5.1 cm in the second and third visits, respectively (p=0.029). The mean size of renal angiomyolipomas significantly decreased (p<0.001). A significant trend toward a decrease in the number of skin lesions was observed (p<0.0001). No relationship was observed between the effects of rapamycin and the patient's age or sex (p>0.05). Changes in patients' growth and developmental features were not statistically significant through subsequent visits (p=0.507). This study revealed the effectiveness and safety of rapamycin on TSC among our patients.