The Genetics of Tuberous Sclerosis Complex and Related mTORopathies: Current Understanding and Future Directions.

The mechanistic target of rapamycin (mTOR) pathway serves as a master regulator of cell growth, proliferation, and survival. Upregulation of the mTOR pathway has been shown to cause malformations of cortical development, medically refractory epilepsies, and neurodevelopmental disorders, collectively described as mTORopathies. Tuberous sclerosis complex (TSC) serves as the prototypical mTORopathy. Characterized by the development of benign tumors in multiple organs, pathogenic variants in TSC1 or TSC2 disrupt the TSC protein complex, a negative regulator of the mTOR pathway. Variants in critical domains of the TSC complex, especially in the catalytic TSC2 subunit, correlate with increased disease severity. Variants in less crucial exons and non-coding regions, as well as those undetectable with conventional testing, may lead to milder phenotypes. Despite the assumption of complete penetrance, expressivity varies within families, and certain variants delay disease onset with milder neurological effects. Understanding these genotype-phenotype correlations is crucial for effective clinical management. Notably, 15% of patients have no mutation identified by conventional genetic testing, with the majority of cases postulated to be caused by somatic TSC1/TSC2 variants which present complex diagnostic challenges. Advancements in genetic testing, prenatal screening, and precision medicine hold promise for changing the diagnostic and treatment paradigm for TSC and related mTORopathies. Herein, we explore the genetic and molecular mechanisms of TSC and other mTORopathies, emphasizing contemporary genetic methods in understanding and diagnosing the condition.

Giant cell angiofibroma of gingiva in tuberous sclerosis complex: a case report and literature review.

BACKGROUND: Tuberous sclerosis complex (TSC) is a rare, complex genetic disorder characterized by hamartomas and neoplastic lesions in various organ systems. With the development of radiology and gene testing, the diagnostic criteria for TSC were updated in 2012 at the International Consensus Conference. Intraoral fibromas have long been associated with TSC. However, the incidence of giant cell angiofibroma (GCA) in TSC patients is extremely rare. Here, we report the first case of GCA in the gingival tissue of a patient with TSC. CASE PRESENTATION: A 41-year-old woman first visited the Department of Oral and Maxillofacial Surgery, Chonnam National University Dental Hospital, complaining of gingival enlargement. Clinical examination revealed several manifestations associated with TSC, including intraoral fibromas, facial angiofibromas, dental enamel pits, ungual fibromas, "confetti" skin lesions, hypomelanotic macules, and a shagreen patch. Intraoral examination revealed a 6.0 × 5.0 cm gingival overgrowth on the left mandible. Surgical excision was performed, and subsequent histopathological examination confirmed the diagnosis of GCA. There was no evidence of recurrence within the 24- months of surgery. CONCLUSIONS: We report the first case of GCA in the gingival tissue of a patient with TSC. This report would contribute to an improved understanding of this rare disease. However, further case reports are necessary to clarify the relationship between GCA and TSC.

Tuberous sclerosis complex: A clinical diagnosis in Ethiopian patients.

RATIONALE: Tuberous sclerosis complex (TSC) is a rare autosomal dominant inherited disorder characterized by the development of nonmalignant tissue growths (hamartomas) in various organ systems, often located in the brain, skin, heart, lung and kidneys. The delayed diagnosis could be attributed to low expectation or exposure of physicians to this rare disease. High index of clinical suspicion is required for early diagnosis of rare diseases to prevent adverse outcomes. PATIENT CONCERNS: The first patient, a 27-year-old man, presented with intermittent left flank pain and hematuria of 5 months duration. On examination of the skin and oral cavity, he had fibrous cephalic plaque, facial angiofibromas, ungual fibromas, confetti skin lesions, and intraoral fibromas. A CT scan of the chest, abdomen, and brain displayed cystic lung parenchymal changes and multifocal micronodular pneumocyte hyperplasia, angiomyolipomas in both kidneys, and multiple calcified subependymal nodules (SEN), respectively. The second patient, a 28-year-old woman, presented with a seizure disorder in the last 1 year, and papular and nodular lesions over her face since childhood. On examination of the skin and oral cavity, she had hypomelanotic macules, facial angiofibromas, shagreen patches, ungual fibromas, intraoral fibromas, and dental enamel pits. DIAGNOSES: Definitive diagnosis of TSC was made in both patients using the "2012 tuberous sclerosis complex diagnostic criteria consensus statement." INTERVENTIONS: The first patient was seen by various medical discipline teams, and suggested close follow-up in the "chronic illness clinic" of the hospital. The second patient was scheduled in dermatology clinic for electrocautery for disfiguring facial nodules. OUTCOME: Both patients were scheduled for close follow-up in the hospital. LESSONS: The patients described had TSC using "clinical diagnostic criteria." Under the clinical diagnostic criteria of TSC, 4 of 11 major criteria and 3 of 7 minor criteria are skin features. Hence, awareness on skin features as clinical markers to suspect TSC should be emphasized in resource-limited countries.

Neuropsychiatric manifestations of tuberous sclerosis in a young man in a psychiatric hospital in Botswana: a case report.

Tuberous sclerosis complex (TSC), first described in 1880, is a disorder that affects multiple systems. Its symptoms include seizures, intellectual disability, and angiofibromas. TSC is caused by mutations in the TSC1 and TSC2 genes and is inherited in an autosomal dominant manner. The present report describes the case of a patient with an unusual psychological presentation who was evaluated in a psychiatric hospital. A man with poorly managed epilepsy was brought to Botswana's only psychiatric hospital. After clinical assessment, a diagnosis of tuberous sclerosis complex was made, which was later confirmed through neuroimaging and genetic tests. Some of the patient's relatives also showed similar neuropsychiatric symptoms. Given that psychiatry may be the first medical contact for TSC patients, especially in low-resource settings, clinicians need to be knowledgeable of various neuropsychiatric conditions and be aware of the possibility of TSC in patients that present with neurocutaneous manifestations. A multidisciplinary team approach is vital for the investigation and management of such cases.

Pathology of hereditary renal cell carcinoma syndromes: Tuberous sclerosis complex (TSC).

Tuberous sclerosis complex (TSC) is an autosomal dominant genetic disease characterized by hamartomatous tumors involving multiple organs such as the brain, skin, heart, lung and kidney. TSC is caused by inactivating mutations in TSC1/TSC2, which encodes hamartin and tuberin, respectively, and forms a complex that regulates mechanistic target of rapamycin complex 1 (mTORC1), resulting in cell overgrowth and oncogenesis. Since a leading cause of morbidity and mortality in TSC relates to chronic kidney disease and the ability to preserve renal function, this review describes the important pathologic findings in TSC-associated renal neoplasms and their correlating sporadic counterparts. The most common renal tumor in TSC patients are AMLs, followed by a heterogeneous spectrum of renal epithelial tumors, which may provide clues to establishing a diagnosis of TSC.

Is tuberous sclerosis complex-associated autism a preventable and treatable disorder?

BACKGROUND: Tuberous sclerosis complex (TSC) is a genetic disorder caused by inactivating mutations in the TSC1 and TSC2 genes, causing overactivation of the mechanistic (previously referred to as mammalian) target of rapamycin (mTOR) signaling pathway in fetal life. The mTOR pathway plays a crucial role in several brain processes leading to TSC-related epilepsy, intellectual disability, and autism spectrum disorder (ASD). Pre-natal or early post-natal diagnosis of TSC is now possible in a growing number of pre-symptomatic infants. DATA SOURCES: We searched PubMed for peer-reviewed publications published between January 2010 and April 2023 with the terms "tuberous sclerosis", "autism", or "autism spectrum disorder"," animal models", "preclinical studies", "neurobiology", and "treatment". RESULTS: Prospective studies have highlighted that developmental trajectories in TSC infants who were later diagnosed with ASD already show motor, visual and social communication skills in the first year of life delays. Reliable genetic, cellular, electroencephalography and magnetic resonance imaging biomarkers can identify pre-symptomatic TSC infants at high risk for having autism and epilepsy. CONCLUSIONS: Preventing epilepsy or improving therapy for seizures associated with prompt and tailored treatment strategies for autism in a sensitive developmental time window could have the potential to mitigate autistic symptoms in infants with TSC.

Complete Remission of a Diffuse Large B-Cell Lymphoma in a Young Patient, with Severe Tuberous Sclerosis, Treated with Metronomic Chemotherapy and Ibrutinib: A Case Report.

Tuberous sclerosis (TS) is a rare autosomal dominant genetic multisystem disease caused by mutations in either the TSC1 or TSC2 gene and results in the growth of non-cancerous masses in several organs. Diffuse large B-cell lymphoma (DLBCL) is the predominant non-Hodgkin lymphoma in adolescents and young adults. Metronomic chemotherapy (mCHEMO) can be defined as the frequent, regular administration of drug doses able to maintain a low, but active, range of concentrations of chemotherapeutic drugs during prolonged periods of time. We present the case of a young woman with severe TS who developed DLBCL. She was treated consecutively with the mCHEMO schedule R-DEVEC (prednisone, vinorelbine, etoposide, cyclophosphamide, plus rituximab) and then ibrutinib, achieving an impressive long-lasting complete remission. In conclusion, alternative treatments could be necessary when comorbidities are present in patients, and mCHEMO can be a potential successful therapeutic approach in frail subjects.

An Autopsy Case of Abdominal Aortic Aneurysm in a Pediatric Decedent With Tuberous Sclerosis Complex.

ABSTRACT: Vascular involvement in tuberous sclerosis complex (TSC) is uncommon and even more so in pediatric patients. When asymptomatic, these vascular abnormalities carry increased risk of rupture with increased morbidity and mortality. Here, we describe a case of a ruptured unrecognized abdominal aortic aneurysm in an 11-month-old patient with a history of TSC. The abdominal aortic aneurysm was discovered at autopsy and highlights the rarity of abdominal aortic aneurysm in pediatric patients diagnosed with TSC and the importance of screening for associated aneurysmal disease in the pediatric population with TSC. Furthermore, the extensive retroperitoneal hemorrhage seen in this case also highlights a rare but potential mimic of abuse in the pediatric population.

Comparative study on genomic and epigenomic profiles of retinoblastoma or tuberous sclerosis complex via nanopore sequencing and a joint screening framework.

Recurrence and extraocular metastasis in advanced intraocular retinoblastoma (RB) are still major obstacles for successful treatment of Chinese children. Tuberous sclerosis complex (TSC) is a very rare, multisystemic genetic disorder characterized by hamartomatous growth. In this study, we aimed to compare genomic and epigenomic profiles with human RB or TSC using recently developed nanopore sequencing, and to identify disease-associated variations or genes. Peripheral blood samples were collected from either RB or RB/TSC patients plus their normal siblings, followed by nanopore sequencing and identification of disease-specific structural variations (SVs) and differentially methylated regions (DMRs) by a systematic biology strategy named as multiomics-based joint screening framework. In total, 316 RB- and 1295 TSC-unique SVs were identified, as well as 1072 RB- and 1114 TSC-associated DMRs, respectively. We eventually identified 6 key genes for RB for further functional validation. Knockdown of CDK19 with specific siRNAs significantly inhibited Y79 cellular proliferation and increased sensitivity to carboplatin, whereas downregulation of AHNAK2 promoted the cell growth as well as drug resistance. Those two genes might serve as potential diagnostic markers or therapeutic targets of RB. The systematic biology strategy combined with functional validation might be an effective approach for rare pediatric malignances with limited samples and challenging collection process.

Cancer Predisposition Syndromes in Neuro-oncology.

Although most primary central and peripheral nervous system (NS) tumors occur sporadically, there are a subset that may arise in the context of a cancer predisposition syndrome. These syndromes occur due to a pathogenic mutation in a gene that normally functions as a tumor suppressor. With increased understanding of the molecular pathogenesis of these tumors, more people have been identified with a cancer predisposition syndrome. Identification is crucial, as this informs surveillance, diagnosis, and treatment options. Moreover, relatives can also be identified through genetic testing. Although there are many cancer predisposition syndromes that increase the risk of NS tumors, in this review, we focus on three of the most common cancer predisposition syndromes, neurofibromatosis type 1, neurofibromatosis type 2, and tuberous sclerosis complex type 1 and type 2, emphasizing the clinical manifestations, surveillance guidelines, and treatment options.

Solitary atrial Rhabdomyoma in an infant with tuberous sclerosis: a case report and review of the literature.

BACKGROUND: Despite its rare incidence of 1/40,000, fetal cardiac rhabdomyoma (CR) represents the prevailing type of benign cardiac fetal tumors, which commonly affects the ventricles. Fetal CRs rarely occur in the right atrium. Thus, the presentation of atrial fibrillation and premature atrial contractions (PAC) due to a solitary cardiac rhabdomyoma is an extremely rare scenario. Our literature review found that only 2% (1 out of 61) of rhabdomyoma cases were found in the right atrium. The majority of fetal cardiac rhabdomyomas are associated with tuberous sclerosis complex (TSC). CASE PRESENTATION: A 7-day-old male neonate presented with arrhythmias and an atrial mass for further evaluation. Echocardiography revealed a hyperechoic, round, uniform right atrial mass (25 mm). An abdominal and testicular ultrasound showed multiple thin-walled cortical cysts in both kidneys and a scrotal hydrocele, respectively. His laboratory workup was insignificant except for hypomagnesemia. Electrocardiography revealed junctional rhythm and PACs with wave distortions. A brain magnetic resonance imaging scan revealed multiple subependymal lesions on the frontal and occipital horns of the lateral ventricles. These findings (Fig. 1), along with a family history of TSC, confirmed the diagnosis of TSC with associated CR. The patient was treated symptomatically with an anti-convulsant and monitored with regular follow-ups. Surgical resection was not required. CONCLUSION: Despite CR's predominance in the ventricles, a diagnosis of rhabdomyoma should be kept in mind in the presence of a solitary atrial mass and PACs. Physicians should evaluate systemic findings related to TSC and provide appropriate follow-up and family screening. Surgical resection is not always required, and symptom management can be achieved through medical treatment alone.

Neurocutaneous Disorders in Pregnancy.

Importance: Neurocutaneous disorders have significant implications for care of the pregnant patient. As neurocutaneous disorders are uncommon, obstetricians may be unfamiliar with these disorders and with recommendations for appropriate care of this population. Objective: This review aims to summarize existing literature on the interaction between neurocutaneous disorders and pregnancy and to provide a guide for physicians caring for an affected patient. Evidence Acquisition: A PubMed, MEDLINE, and Google Scholar search was carried out with a broad range of combinations of the medical subject headings (MeSH) terms "pregnancy," "Sturge -Weber," "Neurofibromatosis Type 1," "neurofibromatosis type 2," "von Hippel Lindau," "Tuberous Sclerosis," "neurocutaneous disorder," "treatment," "congenital malformations," "neurodevelopmental defects," "miscarriage," "breastfeeding," "autoimmune," "pathophysiology," and "management." References of included articles were searched to identify any articles that may have been missed after the above method was used. Results: Neurocutaneous disorders are associated with increased pregnancy-associated maternal and fetal/neonatal morbidity, largely surrounding hypertensive disorders, epilepsy, and medication exposure. Some features of neurocutaneous disorders may be worsened or accelerated by pregnancy. Neurocutaneous disorders can often be diagnosed prenatally. Therefore, directed assessment should be offered to affected individuals with a personal or family history of a neurocutaneous disorder. Conclusion and Relevance: Patients affected by neurocutaneous disorders who are pregnant or planning for future pregnancy should be carefully followed by a multidisciplinary team, which could include maternal-fetal medicine, neurology, and anesthesia, as well as other relevant subspecialists. Additional research is required regarding optimal counseling and management of these patients.

Identification of a Novel TSC2 c.170G>A Missense Variant: A Case Report and Elaboration on the Yield of Targeted Options against Tuberous Sclerosis Complex Manifestations.

BACKGROUND: Tuberous sclerosis complex (TSC) is a rare genetic disease that affects multiple organs and affects the quality of life. Mutations in TSC1 and TSC2 genes are causing dysregulations in the mammalian target of the rapamycin (mTOR) pathway, inducing mostly benign but also malignant tumors, including renal cell carcinoma (RCC). The diagnosis of TSC, based on established clinical and genetic criteria, is essential for the optimal surveillance and management of patients. CASE PRESENTATION: With the current report, we present the case of two sisters who were consequently diagnosed with early-stage chromophobe-like RCC, possibly familial given their young age. The younger sister also had a previous diagnosis of differentiated thyroid carcinoma, for which she had been treated properly. Genetic testing of both revealed the same heterozygous TSC2 variant that is currently regarded as a variant of unknown significance, while both patients did not fulfill the clinical criteria for the diagnosis of TSC. Owing to these data, we opted to manage and surveil both sisters as TSC patients, while we also considered the specific TSC2 variant to be pathogenic - but of low penetrance - based on clinical judgment and functional analyses. Furthermore, we discussed the implementation of mTOR inhibitors for the treatment of TSC complications. CONCLUSION: As novel pathogenic variants of TSC genes are constantly being explored, the identification of TSC variants of unknown significance in combination with absent clinical diagnostic criteria cannot exclude a TSC diagnosis. We support the implementation of clinical judgment in assisting the diagnosis of TSC, as well as the enrollment of patients in clinical trials due to the rarity of the disease.

Updated clinical recommendations for the management of tuberous sclerosis complex associated epilepsy.

Children with tuberous sclerosis complex (TSC), may experience a variety of seizure types in the first year of life, most often focal seizure sand epileptic spasms. Drug resistance is seen early in many patients, and the management of TSC associated epilepsy remain a major challenge for clinicians. In 2018 clinical recommendations for the management of TSC associated epilepsy were published by a panel of European experts. In the last five years considerable progress has been made in understanding the neurobiology of epileptogenesis and three interventional randomized controlled trials have changed the therapeutic approach for the management of TSC associated epilepsy. Pre-symptomatic treatment with vigabatrin may delay seizure onset, may reduce seizure severity and reduce the risk of epileptic encephalopathy. The efficacy of mTOR inhibition with adjunctive everolimus was documented in patients with TSC associated refractory seizures and cannabidiol could be another therapeutic option. Epilepsy surgery has significantly improved seizure outcome in selected patients and should be considered early in all patients with drug resistant epilepsy. There is a need to identify patients who may have a higher risk of developing epilepsy and autism spectrum disorder (ASD). In the recent years significant progress has been made owing to the early identification of risk factors for the development of drug-resistant epilepsy. Better understanding of the mechanism underlying epileptogenesis may improve the management for TSC-related epilepsy. Developmental neurobiology and neuropathology give opportunities for the implementation of concepts related to clinical findings, and an early genetic diagnosis and use of EEG and MRI biomarkers may improve the development of pre-symptomatic and disease-modifying strategies.

Tuberous sclerosis complex: a case report and literature review.

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder with different initial symptoms and complex clinical manifestations. A 14-year-old female patient presented with persistent fever and severe headache. Medical imaging examinations revealed multiple abnormal intracranial lesions. The patient had previously been misdiagnosed with "encephalitis and acute disseminated encephalomyelitis" after visiting numerous hospitals. Eventually, by combing the characteristics of the case and genetic testing results, the patient was diagnosed with TSC accompanied by Mycoplasma pneumoniae infection. The purpose of this case report and literature review is to improve understanding of the clinical diagnosis and treatment of TSC so as to avoid misdiagnosis, missed diagnosis, and overtreatment.