TSC2 Research Articles

Incidental diagnosis of lymphangioleiomyomatosis in gynecological surgery-a case series

Lymphangioleiomyomatosis (LAM) is arare, slow progressing, low-grade neoplasia that primarily effects young women. The disease is well known for its pulmonary involvement with cystic destruction, but extra-pulmonary disease may occur. LAM is associated with mutations in the TSC1 or TSC2 genes and may develop sporadically or in the context of hereditary disease tuberous sclerosis complex (TSC). Incident LAM may represent the sentinel finding of the disease. Raising awareness for rare extrapulmonary LAM lesions in retroperitoneum and pelvic cavity. Data-based research was performed for LAM in gynecological surgical specimens. H&E-stained slides were re-examined, and immunohistochemical stains were re-evaluated. Clinical data were retrieved for the presence pulmonary LAM or TSC. A total of 13cases were identified. The age of the patients ranged from 32to 77years, and 8/13 were ≤ 55years. Two women had ahistory of pulmonary LAM and TSC. Most women underwent surgery for gynecological malignancy. On histological examination, 10/13patients presented LAM in 1to 9lymph nodes with alesion size of 0.5to 12.0 mm, mainly located subcapsular or in the nodal parenchyma. Three of the 13women showed extranodal involvement of the retroperitoneum, myometrium, and the hilum of the ovary. Immunohistochemically LAM was positive for HMB45, desmin, and smooth muscle actin. LAM is arare systemic disease that mainly involves the lungs. Nevertheless, extra-pulmonary manifestations may occur. It is important to report the incidental finding of even small foci of LAM within the pathology report. Incidental LAM may represent the sentinel lesion for pulmonary LAM and/or TSC.

Human TSC2 mutant cells exhibit aberrations in early neurodevelopment accompanied by changes in the DNA Methylome.

Tuberous Sclerosis Complex (TSC) is a debilitating developmental disorder characterized by a variety of clinical manifestations. While benign tumors in the heart, lungs, kidney, and brain are all hallmarks of the disease, the most severe symptoms of TSC are often neurological, including seizures, autism, psychiatric disorders, and intellectual disabilities. TSC is caused by loss of function mutations in the TSC1 or TSC2 genes and consequent dysregulation of signaling via mechanistic Target of Rapamycin Complex 1 (mTORC1). While TSC neurological phenotypes are well-documented, it is not yet known how early in neural development TSC1/2-mutant cells diverge from the typical developmental trajectory. Another outstanding question is the contribution of homozygous-mutant cells to disease phenotypes and whether phenotypes are also present in the heterozygous-mutant populations that comprise the vast majority of cells in patients. Using TSC patient-derived isogenic induced pluripotent stem cells (iPSCs) with defined genetic changes, we observed aberrant early neurodevelopment in vitro, including misexpression of key proteins associated with lineage commitment and premature electrical activity. These alterations in differentiation were coincident with hundreds of differentially methylated DNA regions, including loci associated with key genes in neurodevelopment. Collectively, these data suggest that mutation or loss of TSC2 affects gene regulation and expression at earlier timepoints than previously appreciated, with implications for whether and how prenatal treatment should be pursued.

Fibroblast transcriptomics uncovers pathogenic genomic variants in individuals with exome-negative childhood onset epilepsy.

This study aims to improve genetic diagnosis in childhood onset epilepsy with neurodevelopmental problems by utilizing RNA sequencing of fibroblasts to identify pathogenic variants that may be missed by exome sequencing and copy number variation analysis. We enrolled 41 individuals with childhood onset epilepsy and neurodevelopmental problems who previously had inconclusive genetic testing. Fibroblast samples were cultured and analyzed using RNA sequencing to detect aberrant expression, aberrant splicing, and monoallelic expression using the Detection of RNA Outlier Pipeline (DROP) pipeline. Detected events were correlated with phenotypes, and long-read genome sequencing was performed on individuals with strong candidate events to identify the causal genomic variant. A systematic literature review on RNA sequencing in rare disorders was conducted to contextualize our findings. RNA sequencing identified five strong candidate events in four individuals, affecting the genes QRICH1, TSC1, SMARCA1, GNAI1, and PTEN. (Likely) pathogenic genomic variants affecting expression of QRICH1, TSC1, and SMARCA1 were detected, resulting in a diagnostic yield of 7% (3/41). Two variants were not covered in the initial exome sequencing data but were revealed through long-read sequencing. The identification of a pathogenic TSC1 variant led to a previously unrecognized diagnosis of tuberous sclerosis complex. This prompted guideline-based screening, which revealed tuberous sclerosis lesions in the brain and lung, directly impacting clinical care. Notably, two of the three pathogenic events would not have been detected using whole blood due to the lack of expression of the involved genes. The lower yield of this study compared to studies in other rare disorders reflects the genetic heterogeneity of epilepsy and neurodevelopmental disorders, and the inaccessibility of affected tissue. This research underscores RNA sequencing of cultured fibroblasts as a valuable tool in genetic diagnostics for childhood onset epilepsy, particularly when conventional methods fail. Expanding the control dataset with age-matched samples and incorporating RNA sequencing with nonsense-mediated decay inhibition could further enhance diagnostic yield.

Genotype-phenotype correlation for skin and neuropsychiatric features in tuberous sclerosis complex.

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder caused by pathogenic variants in the TSC1 and TSC2 genes. This condition manifests as diverse symptoms across multiple organ systems and is frequently associated with neuropsychiatric symptoms. However, the relationship between the severity of these manifestations remains poorly understood. This study aimed to elucidate correlations between the severity of various skin and neuropsychiatric symptoms and the underlying TSC1/TSC2 gene pathology.

Newborn with Refractory Seizures due to Hemimegalencephaly and Tuberous Sclerosis Complex: Case Report and Literature Review.

Hemimegalencephaly (HME) is a rare congenital disorder that is initiated during embryonic development with abnormal growth of one hemisphere. Tuberous sclerosis complex (TSC), a genetic disorder, is rarely associated with HME.We present a case of a newborn with HME with a confirmed mutation in the TSC-1 gene and describe the clinical course, findings on amplitude-integrated electroencephalography (aEEG), cranial ultrasound (CUS), MRI, and the postmortem evaluation. Furthermore, we conducted a comprehensive literature review of all reported newborns with HME and a genetically confirmed TSC mutation.This infant experienced therapy-resistant seizures after birth despite treatment with multiple antiseizure medications. CUS and MRI revealed HME of the left hemisphere. Early functional hemispherectomy, around the age of 3 months, was considered but dismissed after multidisciplinary evaluation, medical ethical consultation, and multiple discussions with the parents. Care was redirected due to worsening clinical and neurologic conditions, increasing respiratory insufficiency, and ongoing therapy-resistant seizures. Postmortem evaluation of the brain revealed hamartomatous brain changes and irregular gyration of the enlarged hemisphere. in addition, these changes were also present in the previously considered unaffected side, raising thoughts about the potential effectiveness of functional hemispherectomy.This case report illustrates that in cases with TSC abnormalities might not be confined solely to the initially considered affected side. This can have important therapeutic implications.

Resting state EEG in young children with Tuberous Sclerosis Complex: associations with medications and seizures

BackgroundTuberous Sclerosis Complex (TSC) is a rare genetic condition caused by mutation to TSC1 or TSC2 genes, with a population prevalence of 1/7000 births. TSC manifests behaviorally with features of autism, epilepsy, and intellectual disability. Resting state electroencephalography (EEG) offers a window into neural oscillatory activity and may serve as an intermediate biomarker between gene expression and behavioral manifestations. Such a biomarker could be useful in clinical trials as an endpoint or predictor of treatment response. However, seizures and antiepileptic medications also affect resting neural oscillatory activity and could undermine the utility of resting state EEG features as biomarkers in neurodevelopmental disorders such as TSC.MethodsThis paper compares resting state EEG features in a cross-sectional cohort of young children with TSC (n = 49, ages 12–37 months) to 49 age- and sex-matched typically developing controls. Within children with TSC, associations were examined between resting state EEG features, seizure severity composite score, and use of GABA agonists.ResultsCompared to matched typically developing children, children with TSC showed significantly greater beta power in permutation cluster analyses. Children with TSC also showed significantly greater aperiodic offset (reflecting nonoscillatory neuronal firing) after power spectra were parameterized using SpecParam into aperiodic and periodic components. Within children with TSC, both greater seizure severity and use of GABAergic antiepileptic medication were significantly and independently associated with increased periodic peak beta power.ConclusionsThe elevated peak beta power observed in children with TSC compared to matched typically developing controls may be driven by both seizures and GABA agonist use. It is recommended to collect seizure and medication data alongside EEG data for clinical trials. These results highlight the challenge of using resting state EEG features as biomarkers in trials with neurodevelopmental disabilities when epilepsy and anti-epileptic medication are common.

Neuropsychiatric profile in tuberous sclerosis complex patients with epilepsy.

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder characterized by mutations in the TSC1 or TSC2 genes, leading to dysregulation of the mTOR pathway and multisystemic manifestations. Epilepsy is a common neurologic feature of TSC, frequently accompanied by neuropsychiatric comorbidities. Understanding the relationship between epilepsy severity, TSC-associated neuropsychiatric disorders (TAND), and cognitive outcomes is crucial for optimizing patient care. A retrospective study was conducted at a pediatric tertiary care hospital in Qatar, involving 38 TSC patients (20 female, 18 male) aged 1-18 years, diagnosed between October 2018 and March 2020. Epilepsy severity was assessed using the Early Childhood Epilepsy Severity Scale (E-Chess), and TAND was evaluated using the TAND checklist. Genetic analysis was performed for all patients, and statistical analyses were used to explore correlations between epilepsy severity, TAND, and cognitive outcomes. The majority (82%) of TSC patients had epilepsy, with a mean onset age of 9.2 months. Uncontrolled seizures were associated with higher rates of intellectual disability and more pronounced TAND manifestations compared to controlled seizures. Autism spectrum disorder (ASD) was reported in 42% of the cohort, with significant correlations found between epilepsy severity and ASD-related domains on the TAND checklist. Intellectual disability was prevalent (67.6%), with variability attributed to genetic background and early severe neurological presentations. This study reinforces the link between epilepsy severity and neuropsychiatric comorbidities in TSC, confirming earlier findings. Significant correlations were observed between epilepsy severity and ASD-related domains, and the high prevalence of intellectual disability in TSC patients was highlighted. However, the relationship between ASD, TSC, and epilepsy remains complex and requires further investigation. Despite advances in treatment options, including mTOR inhibitors and newer antiepileptic drugs, unmet needs remain in the comprehensive care of TSC patients. Optimizing seizure control is a clear priority, but equally important is the need for addressing the cognitive and behavioral components of TAND. Early intervention with tailored, multidisciplinary approaches including neurology, psychiatry, psychology, and educational specialists could mitigate the long-term impact of these comorbidities, particularly in children. These approaches must be individualized to each patient's unique set of challenges, emphasizing not only seizure control but also psychosocial support and educational adaptation to improve their overall quality of life. This study sheds light on the intricate interactions between epilepsy severity, neuropsychiatric manifestations, and cognitive outcomes in TSC patients. The findings emphasize the need for tailored management approaches, focusing on early seizure control and comprehensive multidisciplinary care. Further research is required to clarify the mechanisms underlying these associations and to develop targeted interventions for improving the quality of life for individuals with TSC and epilepsy.

The Development of Methods of BLOTCHIP®-MS for Peptidome: Small Samples in Tuberous Sclerosis.

Mutations in TSC1 or TSC2 in axons induce tuberous sclerosis complex. Neurological manifestations mainly include epilepsy and autism spectrum disorder (ASD). ASD is the presenting symptom (25-50% of patients). ASD was observed at significantly higher frequencies in participants with TSC2 than those with TSC1 mutations. The occurrence of TSC2 mutations is about 50% larger than TSC1. Therefore, ASD may develop due to TSC2 deficiency. TSC2 regulates microRNA biogenesis and Microprocessor activity via GSK3β. Of reference, everolimus has the best treatment target because of the higher potency of interactions with mTORC2 rather than rapamycin. Mutations in the TSC1 and TSC2 genes result in the constitutive hyperactivation of the mammalian target of the rapamycin (mTOR) pathway, contributing to the growth of benign tumors or hamartomas in various organs. TSC2 mutations were associated with a more severe phenotypic spectrum than TSC1 mutations because of the inhibition of the mTOR cascade. There are few studies on the peptide analysis of this disorder in relation to everolimus. Only one study reported that, in ten plasma samples, pre-melanosome protein (PMEL) and S-adenosylmethionine (SAM) were significantly changed as diagnostic prognostic effects. Our study on peptide analysis in Protosera Inc (Osaka, Japan) revealed that three peptides that were related to inflammation in two patients with tuberous sclerosis, who showed a 30% decrease in ASD symptoms following everolimus treatment. TSC2 mutations were associated with a more severe phenotypic spectrum due to the inhibition of the mTOR cascade. PMEL and SAM were significantly changed as diagnostic effects.

Long-term neuropsychologic outcome of pre-emptive mTOR inhibitor treatment in children with tuberous sclerosis complex (TSC) under 4 months of age (PROTECT), a two-arm, randomized, observer-blind, controlled phase IIb national multicentre clinical trial: study protocol

BackgroundTuberous sclerosis complex (TSC) is an autosomal dominant genetic disorder affecting multiple organ systems, with a prevalence of 1:6,760–1:13,520 live births in Germany. On the molecular level, TSC is caused by heterozygous loss-of-function variants in either of the genes TSC1 or TSC2, encoding the Tuberin-Hamartin complex, which acts as a critical upstream suppressor of the mammalian target of rapamycin (mTOR), a key signaling pathway controlling cellular growth and metabolism. Despite the therapeutic success of mTOR inhibition in treating TSC-associated manifestations, studies with mTOR inhibitors in children with TSC above two years of age have failed to demonstrate beneficial effects on disease-related neuropsychological deficits. It has thus been hypothesized, that the critical time window for mTOR inhibitors may lie in early infancy, before TSC-related symptoms such as early-onset epilepsy and infantile spasms as sign of disruptive brain maturation occur. No controlled prospective clinical trials have evaluated the effect of pre-symptomatic mTOR inhibitor therapy on neuropsychological manifestations in TSC patients under two years of age.MethodsThis two-arm, randomized, observer-blind, phase IIb national multicenter clinical trial aims at investigating the long-term neuropsychologic outcomes of pre-emptive mTOR inhibitor treatment in children diagnosed with TSC under four months of age. Sixty participants will be allocated to the trial with a 1:1 randomization ratio. The primary endpoint will be the neuropsychological outcome assessed by the cognitive scale of the Bayley Scales of Infant and Toddler Development III at 24 months of age compared to Standard of Care. Secondary endpoints include neuropsychologic outcomes at 12 months of age, seizure frequency, cardiac and cerebral tumor load, and safety assessments. Inclusion criteria are a definite TSC diagnosis and an age below four months at enrolment. The investigational medicinal product is sirolimus (Rapamune®), administered orally based on body surface area and surveilled by pharmacokinetic measurements, starting within the first four months of life and continuing until the second birthday.ConclusionThis study addresses a critical gap in understanding the impact of pre-emptive mTOR inhibitor therapy on neuropsychologic outcomes in young TSC patients, aiming to improve overall patient outcomes and quality of life.EUCT number: 2022–502332-39–00, Registered 22/06/2023, https://euclinicaltrials.eu/search-for-clinical-trials/?lang=en&EUCT=2022-502332-39-00

Clinicopathological features and molecular genetic changes of primary renal hemangioblastoma, a TSC-associated tumor.

Renal hemangioblastoma (HB) is a rare extra-central nervous system (CNS) tumor, typically not linked to Von Hippel-Lindau (VHL) Syndrome, and its underlying genetic drivers and molecular mechanisms remain elusive. The objective of this study is to investigate the clinicopathological features and molecular genetic changes of primary renal hemangioblastomas. Herein, the clinical, imaging, clinicopathological features, and immunophenotype in 3 cases of renal HB were retrospectively analyzed. Next generation sequencing (NGS) was employed to detect 116 gene loci, including VHL gene. Three patients (two males and one female) aged between 39 and 61 presented with renal masses detected by physical examination or imaging. Macroscopically, the tumors were well-demarcated, with a fibrous capsule and a grayish-yellow to brown, solid, medium-texture cut surface. Microscopically, the tumor cells were polygonal to oval and were separated by thin-walled branching capillaries into sheets and nests. The cells exhibited abundant, translucent, or pale pink cytoplas. Immunohistochemical (IHC) staining showed diffuse positivity for S-100 protein (3/3), Vimentin (3/3), α-Inhibin (3/3), and NSE (3/3) in all cases, with focal positivity for AE1/AE3, EMA, CD10, and PAX-8. Staining for SMA, CgA, Syn, HMB-45, and Melan-A was negative. CD31 and CD34 highlighted an abundant vascular network. NGS revealed TSC1 gene alterations in all 3 cases, with no VHL gene mutation detected. Primary renal HB is a rare mesenchymal tumor that requires differentiation from clear cell renal cell carcinoma (CCRCC) using morphological, IHC markers, and genetic testing when necessary. TSC1 could be a specific molecular hallmark of renal HB. Additional case data is required to better understand the molecular genetic alterations of the disease.

Analysis of TSC1 and TSC2 genes and evaluation of phenotypic correlations with tuberous sclerosis.

Tuberous sclerosis complex (TSC) is a rare genetic disorder characterized by the formation of benign tumors in various organs, particularly in the central nervous system. We aimed to delineate the molecular profile of Turkish individuals diagnosed with TSC by analyzing the TSC1 and TSC2 genes using next-generation sequencing (NGS). Sophia Genetics' Sophia Inherited Disease Panel was used to perform NGS on 22 individuals diagnosed with TSC and to identify pathogenic variants in the TSC1 and TSC2 genes. Among the 22 cases, mutations were found in 3 (13.6%) for TSC1 and in 16 (73%) for TSC2, while 3 (13.6%) exhibited no detectable mutations. Notably, one individual with a TSC2 mutation presented with angiofibroma, ungual fibroma, and pitted dental enamel, while another had cardiac rhabdomyoma. Autism spectrum disorders were observed in 6 (27%) with TSC2 mutations, including one with autistic behavior. Abnormal motor development was noted in 3 (13.6%), of which 2 had TSC2 mutations. Severe intellectual disability was found in 3 (13.6%) with TSC2 mutations, and developmental delay was seen in 2 (9%) with TSC2 mutations. Epileptic encephalopathy occurred in 3 (13.6%), with 2 having TSC2 mutations. Additionally, 6 (27%) exhibited drug resistance for focal seizures, with 5 of them having TSC2 mutations. These findings are consistent with other research indicating that TSC2 mutations are associated with a more severe phenotypic range compared to TSC1 mutations. Moreover, our analysis showed that some people with TSC1/TSC2 mutations did not match diagnostic criteria. This highlights the importance of genetic testing and molecular profiling in understanding the clinical variability and aiding in the management of TSC patients.

STAT1 Promotes PD-L1 Activation and Tumor Growth in Lymphangioleiomyomatosis.

Lymphangioleiomyomatosis (LAM) is a cystic lung disease that primarily affects women. LAM is caused by the invasion of metastatic smooth muscle-like cells into the lung parenchyma, leading to abnormal cell proliferation, lung remodeling and progressive respiratory failure. LAM cells have TSC gene mutations, which occur sporadically or in people with Tuberous Sclerosis Complex. Although it is known that hyperactivation of the mechanistic target of rapamycin complex 1 (mTORC1) due to TSC2 gene mutations contributes to aberrant cell growth in LAM lung, tumor origin and invasive mechanism remain unclear. To determine molecular drivers responsible for aberrant LAM cell growth, we performed integrative single-cell transcriptomic analysis and predicted that STAT1 interacts with Pre-B cell leukemia transcription factor (PBX1) to regulate LAM cell survival. Here, we show activation of STAT1 and STAT3 proteins in TSC2-deficient LAM models. Fludarabine, a potent STAT1 inhibitor, induced the death of TSC2-deficient cells, increased caspase-3 cleavage, and phosphorylation of necroptosis marker RIP1. Fludarabine treatment impeded lung colonization of TSC2-deficient cells and uterine tumor progression, associated with reduced percentage of PCNA-positive cells in vivo. Interestingly, IFN-γ treatment increased STAT1 phosphorylation and PD-L1 expression, indicating that STAT1 aids TSC2-deficient tumor cells in evading immune surveillance in LAM. Our findings indicate that STAT1 signaling is critical for LAM cell survival and could be targeted to treat LAM and other mTORC1 hyperactive tumors.

CRISPR-Cas9-Mediated Correction of TSC2 Pathogenic Variants in iPSCs from Patients with Tuberous Sclerosis Complex Type 2.

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder caused by mutations in either the TSC1 or TSC2 genes. Though TSC causes the formation of nonmalignant tumors throughout multiple organs, the most frequent causes of mortality and morbidity are due to neurological complications. In two-thirds of cases, TSC occurs sporadically and TSC2 pathogenic variants are approximately three times more prevalent than TSC1 pathogenic variants. Here, we utilized CRISPR-Cas9-mediated homology directed repair in patient induced pluripotent stem cells (iPSCs) to correct two types of TSC2 pathogenic variants generating two isogenic lines. In one line, we corrected a splice acceptor variant (c.2743-1G>A), which causes the skipping of coding exon 23 and subsequent frameshift and introduction of a stop codon in coding exon 25. In the second line, we corrected a missense variant in coding exon 40 within the GTPase-activating protein domain (c.5228G>A, p.R1743Q). The generation of TSC2 patient iPSCs in parallel with their corresponding CRISPR-corrected isogenic lines will be an important tool for disease modeling applications and for developing therapeutics.

Premature cognitive decline in a mouse model of tuberous sclerosis.

Little is known about the influence of (impaired) neurodevelopment on cognitive aging. We here used a mouse model for tuberous sclerosis (TS) carrying a heterozygous deletion of the Tsc2 gene. Loss of Tsc2 function leads to mTOR hyperactivity in mice and patients. In a longitudinal behavioral analysis, we found premature decline of hippocampus-based cognitive functions together with a significant reduction of immediate early gene (IEG) expression. While we did not detect any morphological changes of hippocampal projections and synaptic contacts, molecular markers of neurodegeneration were increased and the mTOR signaling cascade was downregulated in hippocampal synaptosomes. Injection of IGF2, a molecule that induces mTOR signaling, could fully rescue cognitive impairment and IEG expression in aging Tsc2+/- animals. This data suggests that TS is an exhausting disease that causes erosion of the mTOR pathway over time and IGF2 is a promising avenue for treating age-related degeneration in mTORopathies.

Variants of TSC1 are associated with developmental and epileptic encephalopathy and focal epilepsy without tuberous sclerosis

BackgroundThe TSC1 gene encodes a growth inhibitory protein hamartin, which plays a crucial role in negative regulation of the activity of mTORC1 (mechanistic target of rapamycin complex 1). TSC1 has been associated with tuberous sclerosis complex (TSC). This study aims to investigate the association between TSC1 variants and common epilepsy.MethodsTrio-based whole-exome sequencing was performed in epilepsy patients without acquired etiologies from the China Epilepsy Gene 1.0 Project platform. The pathogenicity of the variants was evaluated according to the American College of Medical Genetics and Genomic (ACMG) guidelines.ResultsTwo TSC1 de novo variants, including c.1498 C > T/p.Arg500* and c.2356 C > T/p.Arg786*, were identified in two patients with developmental and epileptic encephalopathy (DEE). The patients exhibited frequent seizures and neurodevelopmental delay. Additionally, we identified two heterozygous TSC1 variants that affected four individuals with focal epilepsy from two unrelated families. The four probands did not present any typical symptom of TSC and had normal brain MRI findings. The four variants were absent in the Genome Aggregation Database (gnomAD) and were predicted to be damaging with a in silico prediction tool. Based on the ACMG guidelines, the four variants were evaluated to be “pathogenic” or “likely pathogenic”. Of the patients in the China Epilepsy Gene 1.0 Project, 22 patients carried TSC1 variants and were diagnosed with TSC. The ratio of patients carrying TSC1 variants with or without TSC is about 5:1.ConclusionsTSC1 is potentially associated with common epilepsy without tuberous sclerosis.

Challenges in the Management of Tuberous Sclerosis-associated Neuropsychiatric Disorders

Abstract Tuberous sclerosis is a rare autosomal dominant multisystem disorder of genetic origin affecting TSC1 and TSC2 genes. Individuals with tuberous sclerosis are affected by a broad range of behavioral, academic, intellectual, psychiatric, and psychosocial problems, typically underidentified and undertreated. We are presenting the case of a young male with tuberous sclerosis presented with seizures followed by the development of behavioral and dermatological manifestations. We faced difficulties in the management due to the lack of appropriate guidelines. Initially, no response was seen with atypical antipsychotics and antidepressants, and when some improvement was noticed with typical antipsychotics, extrapyramidal symptoms intervened in the progress and caused more distress to the patient. Hence, one should focus on early recognition and prompt treatment of the individual suffering from TSC. The lack of proper guidelines for managing neuropsychiatric manifestation poses a significant challenge. More research is needed in this area.

Enhanced Gαq Signaling in TSC2-deficient Cells Is Required for Their Neoplastic Behavior.

Inherited or sporadic loss of the TSC2 gene can lead to pulmonary lymphangioleiomyomatosis (LAM), a rare cystic lung disease caused by protease-secreting interstitial tumor nodules. The nodules arise by metastasis of cells that exhibit features of neural crest and smooth muscle lineage ('LAM cells'). Their aberrant growth is attributed to increased activity of 'mechanistic target of rapamycin complex 1' (mTORC1), an anabolic protein kinase that is normally suppressed by the TSC1-TSC2 protein complex. The mTORC1 inhibitor rapamycin slows the progression of LAM, but fails to eradicate disease, indicating a role for mTORC1-independent mechanisms in LAM pathogenesis. Our previous studies revealed G-protein coupled urotensin-II receptor (UT) signaling as a candidate mechanism, but how it promotes oncogenic signaling in TSC2-deficient cells remained unknown. Using a human pluripotent stem cell-derived in vitro model of LAM, we now show hyperactivation of UT, which was required for their enhanced migration and pro-neoplastic signaling in a rapamycin-insensitive mechanism that required heterotrimeric Gαq/11 (Gαq). Bioluminescence resonance energy transfer assays in HEK 293T cells lacking TSC2 demonstrated selective and enhanced activation of Gαq and its RhoA-associated effectors compared to wild-type control cells. By immunoprecipitation, recombinant UT was physically associated with Gαq and TSC2. The augmented Gαq signaling in TSC2-deleted cells was independent of mTOR activity, and associated with increased endosomal targeting of p63RhoGEF, a known RhoA-activating effector of Gαq. These studies identify potential mTORC1-independent pro-neoplastic mechanisms that can be targeted for prevention or eradication of pulmonary and extrapulmonary LAM tumors.

Germline Variants in DNA Interstrand-Cross Link Repair Genes May Contribute to Increased Susceptibility for Serrated Polyposis Syndrome.

Serrated polyposis syndrome (SPS) is characterized by the development of multiple colorectal serrated polyps and increased predisposition to colorectal cancer (CRC). However, the molecular basis of SPS, especially in cases presenting family history of SPS and/or polyps and/or CRC in first-degree relatives (SPS-FHP/CRC), is still poorly understood. In a previous study, we proposed the existence of two molecular entities amongst SPS-FHP/CRC families, proximal/whole-colon and distal SPS-FHP/CRC, according to the preferential location of lesions and somatic events involved in tumor initiation. In the present study, we aimed to investigate these distinct subgroups of SPS patients in a larger cohort at the germline level and to identify the genetic defects underlying an inherited susceptibility for these two entities. Next-generation sequencing was performed using multigene analysis with a custom-designed panel in a Miseq platform in 60 SPS patients (with and without/unknown FHP/CRC). We found germline pathogenic variants in 6/60 patients (ATM, FANCM, MITF, RAD50, RAD51C, and RNF43). We also found variants of unknown significance (VUS), with prediction of probable damaging effect in 23/60 patients (ATM, BLM, BRCA1, FAN1, ERCC2, ERCC3, FANCA, FANCD2, FANCL, MSH2, MSH6, NTHL1, PALB2, PDGFRA, PMS2, PTCH1, RAD51C, RAD51D, RECQL4, TSC2, WRN, and XRCC5 genes). Most variants were detected in gene coding for proteins of the Fanconi Anemia (FA) pathway involved in the DNA Interstrand-Cross Link repair (ICLR). Notably, variants in ICLR genes were significantly more frequent in the proximal/whole-colon than in the distal subgroup [15/44 (34%) vs 1/16 (6%), p = 0.025], as opposed to the non-ICLR genes that were slightly more frequent in the distal group [8/44 (18%) vs. 5/16 (31%), p > 0.05]. Germline defects in the DNA-ICLR genes may contribute to increased serrated colorectal polyps/carcinoma risk in SPS patients, particularly in proximal/whole-colon SPS. The inclusion of DNA-ICLR genes in the genetic diagnosis of SPS patients, mainly in those with proximal/whole-colon lesions, should be considered and validated by other studies. In addition, patients with germline defects in the DNA-ICLR genes may be more sensitive to treatment with platinum-based therapeutics, which can have implications in the clinical management of these patients.

Molecular and Functional Assessment of TSC1 and TSC2 in Individuals with Tuberous Sclerosis Complex.

Tuberous sclerosis complex (TSC) is an autosomal dominant neurodevelopmental disorder and multisystem disease caused by pathogenic DNA alterations in the TSC1 and TSC2 tumor suppressor genes. A molecular genetic diagnosis of TSC confirms the clinical diagnosis, facilitating the implementation of appropriate care and surveillance. TSC1 and TSC2 encode the core components of the TSC1/2 complex (TSC1/2), a negative regulator of the mechanistic target of rapamycin (MTOR) complex 1 (TORC1). Functional analysis of the effects of TSC1 and TSC2 variants on TORC1 activity can help establish variant pathogenicity. We searched for pathogenic alterations to TSC1 and TSC2 in DNA isolated from 116 individuals with a definite clinical diagnosis of TSC. Missense variants and in-frame deletions were functionally assessed. Pathogenic DNA alterations were identified in 106 cases (91%); 18 (17%) in TSC1 and 88 (83%) in TSC2. Of these, 35 were novel. Disruption of TSC1/2 activity was demonstrated for seven TSC2 variants. Molecular diagnostics confirms the clinical diagnosis of TSC in a large proportion of cases. Functional assessment can help establish variant pathogenicity and is a useful adjunct to DNA analysis.

Central nervous system manifestations of tuberous sclerosis complex: A single centre experience in Qatar.

To review the clinical and radiological correlation of the central nervous system manifestations of tuberous sclerosis complex (TSC). All patients under the age of 18 years with TSC seen at the Department of Pediatrics, Sidra Medicine, Doha, Qatar, between January 2003 and February 2021 were included in this retrospective study. Severity of epilepsy was determined using the early childhood epilepsy severity score (E-CHESS) tool. The study sample included 38 patients (50% male), 8 (21%) of whom were native to Qatar. The median age at diagnosis was 4 (range: 0-72) months. A family history of TSC was present in 10 (26%) cases, while 33 (86%) patients had a TSC2 gene mutation. Common presentations included seizures (79%), rhabdomyoma (26%), and developmental delay (13%). On MRI scans, cortical tubers were seen in all patients, subependymal nodules in 37 (97%), and subependymal giant cell astrocytoma was diagnosed in 8 (21%) cases. A total of 30 children developed epilepsy, 9 of whom had favorable and 21 had unfavorable E-CHESS scores, and 6 required pharmaceutical management. A total of 13 children were diagnosed with autistic spectrum disorder and 12 with attention deficit hyperactivity disorder. Multidisciplinary management and further research is needed to optimize the care and quality of life of TSC affected individuals and their families.