Genetics of tuberous sclerosis complex: implications for clinical practice

Molecular diagnosis of tuberous sclerosis complex in fetuses and infants: an institutional case series

OBJECTIVE

We describe the clinical and genetic characteristics of fetuses and infants diagnosed with tuberous sclerosis complex (TSC) in our centre, prenatally or neonatally, for a better understanding of the benefits of early screening.

METHODS

In this retrospective study, we analysed the data on one fetus and nine infants with a definitive TSC diagnosis by genetic criteria (five patients carrying TSC1 variants and 5 patients carrying TSC2 variants). We explored the differences between phenotypes of patients carrying TSC1 and TSC2 pathogenic variants.

RESULTS

The most common initial presenting features of TSC were cardiac rhabdomyomas (CRs) that were observed in nine out of ten patients. The most common postnatal features, besides CR, were presented with subependymal nodules-in five patients, and hypomelanotic macules-in four patients. In total, 10 variants causing TSC were detected in this study, including 5 novel variants. We demonstrated that patients with TSC2 variants had earlier onset and more severe clinical manifestations compared with patients carrying TSC1 variants.

CONCLUSION

Early diagnosis of TSC improves genetic counselling and perinatal management.

Subependymal Giant Cell Astrocytoma: The Molecular Landscape and Treatment Advances

Subependymal giant cell astrocytoma (SEGA) is most often found in patients with TSC (Tuberous Sclerosis Complex). Although it has been classified as a benign tumor, it may create a serious medical problem leading to grave consequences, including young patient demise. Surgery and chemotherapy belong to the gold standard of treatment. A broader pharmacological approach involves the ever-growing number of rapalogs and ATP-competitive inhibitors, as well as compounds targeting other kinases, such as dual PI3K/mTOR inhibitors and CK2 kinase inhibitors. Novel approaches may utilize noncoding RNA-based therapeutics and are extensively investigated to this end. The purpose of our review was to characterize SEGA and discuss the latest trends in the diagnosis and therapy of this disease.

Epileptic seizures revealing tuberous sclerosis in a tropical environment: A study of 12 case series

Background

Epilepsy remains a significant public health concern in Sub-Saharan Africa (SSA) where diverse etiological factors contribute to its prevalence. Among these factors are conditions originating from the neuroectoderm, such as tuberous sclerosis. Insufficient medical attention and a lack of comprehensive multidisciplinary care contribute to its under-recognition.

Materials and methods

We conducted a retrospective descriptive study, involving 12 patients admitted to the neurology and pediatric departments of the University Hospital Ignace Deen between 2010 and 2022 due to recurring epileptic seizures. Subsequently, these patients were diagnosed with Tuberous sclerosis using the Schwartz 2007 criteria. The aim of this study is to reassess this condition from a clinical and paraclinical point of view in a tropical environment.

Results

Tuberous sclerosis, also known as Bourneville disease, was diagnosed in 12 patients exhibiting focal motor seizures and complex focal seizures likely associated with cortical and subcortical tubers detectable by EEG and neuroimaging, including CT and MRI. Delayed treatment resulted in varying degrees of mental decline. Additionally, some patients displayed cardiac hamartomas and intracranial posterior and anterior aneurysms as minor diagnostic indicators.

Conclusion

The study reveals a consistent clinical presentation accompanied by deteriorating neurological and psychological symptoms attributed to delayed multidisciplinary management. These findings are utilized to assess therapeutic strategies and prognostic outcomes.

Genetics of Cardiac Tumours: A Narrative Review

Cardiac tumours can occur in association with genetic syndromes. Rhabdomyomas have been reported in association with tuberous sclerosis, myxomas with Carney's complex, cardiac fibromas with Gorlin syndrome, and paragangliomas with multiple endocrine neoplasm syndrome. The presentation and prognosis of cardiac tumours associated with genetic syndromes differ compared with sporadic cases. Knowledge about the associated syndromes' genetic features and extracardiac manifestations is essential for the diagnosis, prognosis, and management of cardiac neoplasms. Moreover, identifying genetic mutations in benign and malignant cardiac tumours is needed to personalise management and improve treatment outcomes. Thus, this review discusses the genetic abnormalities associated with cardiac tumours, the current genetic screening recommendations, and the effect of those genetic mutations on the outcomes.

Tuberous sclerosis complex in adulthood: focus on epilepsy prognosis

OBJECTIVE

Typically diagnosed in early childhood or adolescence, TSC is a chronic, multisystemic disorder with age-dependent manifestations posing a challenge for transition and for specific surveillance throughout the lifetime. Data on the clinical features and severity of TSC in adults and on the prognosis of epilepsy are scarce. We analyzed the clinical and genetic features of a cohort of adult patients with TSC, to identify the prognostic predictors of seizure remission after a long follow-up.

METHOD

We conducted a retrospective analysis of patients diagnosed with TSC according to the updated international diagnostic criteria. Pearson's chi-square or Fisher's exact test and Mann Whitney U test were used to compare variables among the Remission (R) and Non-Remission (NR) group. Univariate and multivariate logistic regression analyses were performed.

RESULTS

We selected 43 patients with TSC and neurological involvement in terms of epilepsy and/or brain lesions, attending the Epilepsy Center of our Institute: of them, 16 (37.2%) were transitioning from the pediatric care and 6 (13.9%) were referred by other specialists. Multiorgan involvement includes cutaneous (86.0%), nephrological (70.7%), hepatic (40.0%), ocular (34.3%), pneumological (28.6%) and cardiac (26.3%) manifestations. Thirty-nine patients (90.7 %) had epilepsy. The mean age at seizure onset was 4 ± 7.3 years: most patients (29, 76.3 %) presented with focal seizures or spasms by age 3 years; only 2 (5.3 %) had seizure onset in adulthood. Twenty-seven patients (69.2 %) experienced multiple seizure types overtime, 23 (59.0 %) had intellectual disability (ID). At last assessment, 14 (35.9 %) were seizure free (R group) and 25 (64.1 %) had drug-resistant seizures (NR group). At logistic regression univariate analysis, ID (OR 7.9, 95 % CI 1.8--34.7), multiple seizure types lifelong (OR 13.2, 95 % CI 2.6- 67.2), spasms/tonic seizures at presentation (OR 6.5, 95 % CI 1.2--35.2), a higher seizure frequency at onset (OR 5.4, 95 % CI 1.2--24.3), abnormal neurological examination (OR 9.8, 95 % CI 1.1--90.6) and pathogenic variants in TSC2 (OR 5.4, 95 % CI 1.2--24.5) were significantly associated with non-remission. In the multivariate analysis, both ID and multiple seizure types lifelong were confirmed as independent predictors of poor seizure outcome.

CONCLUSIONS

In our cohort of adult patients with TSC, epilepsy remains one of the main neurological challenges with only 5.3% of cases manifesting in adulthood. Approximately 64% of these patients failed to achieve seizure remission. ID and multiple seizure types were the main predictors of poor outcome. Nephrological manifestations require continuous specific follow-up in adults.

Ectopic HCN4 Provides a Target Biomarker for the Genetic Spectrum of mTORopathies

Background and Objectives

Pathogenic variants in PI3K-AKT-mTOR pathway and GATOR1 complex genes resulting in hyperactivation of mechanistic target of rapamycin (mTOR) complex 1 are a major cause of drug-resistant epilepsy and focal cortical malformations (FCM). Resective neurosurgery is often required to achieve seizure control in patients with mTORopathies due to lack of effectiveness of nonsurgical therapies, including antiseizure medication and mTOR inhibitors. Elevated hyperpolarization-activated cyclic nucleotide-gated potassium channel isoform 4 (HCN4) has been proposed as a key marker in some mTOR-related brain malformations. This study aimed to investigate HCN4 as a biomarker in the brain across the genetic spectrum of mTORopathies in humans.

Methods

Our study investigated the relative steady-state levels and cellular localization of HCN4 in resected human brain tissue from 18 individuals with mTORopathies (3 individuals with tuberous sclerosis complex (TSC) due to TSC2 variants, 5 individuals with focal cortical dysplasia type IIA (FCD IIA) due to genetic variants in MTOR, AKT3, and PIK3CA, and 10 individuals with FCD IIB due to variants in TSC1, MTOR, RHEB, DEPDC5, or NPRL3).

Results

Elevated HCN4 was observed to be highly restricted to abnormal cell types (dysmorphic neurons and balloon cells) in brain tissue from all mTORopathy tissues (p < 0.0001) compared with those in controls, regardless of genetic cause or variant allele frequency. Elevated HCN4 was not observed in controls or individuals with non-mTOR-related focal epilepsy due to pathogenic variants in ATP1A3, SLC35A2, or FGFR1.

Discussion

HCN4 provides a biomarker for the genetic spectrum of mTORopathies and may present a potential therapeutic target for seizure control in mTOR-related epilepsy.

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.

Translatome analysis of tuberous sclerosis complex 1 patient-derived neural progenitor cells reveals rapamycin-dependent and independent alterations

BACKGROUND

Tuberous sclerosis complex (TSC) is an inherited neurocutaneous disorder caused by mutations in the TSC1 or TSC2 genes, with patients often exhibiting neurodevelopmental (ND) manifestations termed TSC-associated neuropsychiatric disorders (TAND) including autism spectrum disorder (ASD) and intellectual disability. Hamartin (TSC1) and tuberin (TSC2) proteins form a complex inhibiting mechanistic target of rapamycin complex 1 (mTORC1) signaling. Loss of TSC1 or TSC2 activates mTORC1 that, among several targets, controls protein synthesis by inhibiting translational repressor eIF4E-binding proteins. Using TSC1 patient-derived neural progenitor cells (NPCs), we recently reported early ND phenotypic changes, including increased cell proliferation and altered neurite outgrowth in TSC1-null NPCs, which were unaffected by the mTORC1 inhibitor rapamycin.

METHODS

Here, we used polysome profiling, which quantifies changes in mRNA abundance and translational efficiencies at a transcriptome-wide level, to compare CRISPR-edited TSC1-null with CRISPR-corrected TSC1-WT NPCs generated from one TSC donor (one clone/genotype). To assess the relevance of identified gene expression alterations, we performed polysome profiling in postmortem brains from ASD donors and age-matched controls. We further compared effects on translation of a subset of transcripts and rescue of early ND phenotypes in NPCs following inhibition of mTORC1 using the allosteric inhibitor rapamycin versus a third-generation bi-steric, mTORC1-selective inhibitor RMC-6272.

RESULTS

Polysome profiling of NPCs revealed numerous TSC1-associated alterations in mRNA translation that were largely recapitulated in human ASD brains. Moreover, although rapamycin treatment partially reversed the TSC1-associated alterations in mRNA translation, most genes related to neural activity/synaptic regulation or ASD were rapamycin-insensitive. In contrast, treatment with RMC-6272 inhibited rapamycin-insensitive translation and reversed TSC1-associated early ND phenotypes including proliferation and neurite outgrowth that were unaffected by rapamycin.

CONCLUSIONS

Our work reveals ample mRNA translation alterations in TSC1 patient-derived NPCs that recapitulate mRNA translation in ASD brain samples. Further, suppression of TSC1-associated but rapamycin-insensitive translation and ND phenotypes by RMC-6272 unveils potential implications for more efficient targeting of mTORC1 as a superior treatment strategy for TAND.

Neurofibromatosis type1, type 2, tuberous sclerosis and Von Hippel-Lindau disease

Neurocutaneous syndromes (also known as phakomatoses) are heterogenous group of disorders that involve derivatives of the neuroectoderm. Each disease has diagnostic and pathognomonic criteria, once identified, thorough clinical examination to the patient and the family members should be done. Magnetic resonance imaging (MRI) is used to study the pathognomonic findings withing the CNS (Evans et al. in Am J Med Genet A 152A:327-332, 2010). This chapter includes the 4 most common syndromes faced by neurosurgeons and neurologists; neurofibromatosis types 1 and 2, tuberous sclerosis and Von Hippel-Lindau disease. Each syndrome has specific genetic anomaly that involves a tumor suppressor gene and the loss of inhibition of specific pathways. The result is a spectrum of cutaneous manifestations and neoplasms.

Retrospective pharmacogenetic study in a cohort of pediatric tuberous sclerosis complex patients using everolimus

Aim: Tuberous sclerosis complex (TSC) is a rare disease that produces multisystemic disorders. Everolimus (EVR) is the only immunosuppressive drug approved to control the symptoms and progression of the disease. The aim was to evaluate the genotype-phenotype association to improve the pediatric TSC pharmacotherapeutic outcome. Patients & methods: Ten pediatric TSC patients were recruited. Concomitant treatment and main metabolic enzymes and transporter coding gene variants of EVR were analyzed. Results: Significant associations were found between CYP3A4*22 allele and concomitant treatment with valproic acid (CYP3A4-inhibitor) with a poor metabolizer phenotype and the presence of pneumonia. Conclusion: This is the first pharmacogenetic study of EVR in pediatric TSC patients. The authors propose to consider concomitant treatment and pharmacogenetics due to their multifactorial status.

Translatome analysis of Tuberous Sclerosis Complex-1 patient-derived neural progenitor cells reveal rapamycin-dependent and independent alterations

Tuberous sclerosis complex (TSC) is an inherited neurocutaneous disorder caused by mutations in TSC1 or TSC2 genes, with patients often exhibiting neurodevelopmental (ND) manifestations termed TSC-associated neuropsychiatric disorders (TAND) including autism spectrum disorder (ASD). The hamartin-tuberin (TSC1-TSC2) protein complex inactivates mechanistic target of rapamycin complex 1 (mTORC1) signaling, leading to increased protein synthesis via inactivation of translational repressor eIF4E-binding proteins (4E-BPs). In TSC1-null neural progenitor cells (NPCs), we previously reported early ND phenotypic changes, including increased proliferation/altered neurite outgrowth, which were unaffected by mTORC1-inhibitor rapamycin. Here, using polysome-profiling to quantify translational efficiencies at a transcriptome-wide level, we observed numerous TSC1-dependent alterations in NPCs, largely recapitulated in post-mortem brains from ASD donors. Although rapamycin partially reversed TSC1-associated alterations, most neural activity/synaptic- or ASD-related genes remained insensitive but were inhibited by third-generation bi-steric, mTORC1-selective inhibitor RMC-6272, which also reversed altered ND phenotypes. Together these data reveal potential implications for treatment of TAND.

Association of multiple retinal nodular hamartomas and "confetti" skin lesions with end-stage renal disease in patients with tuberous sclerosis

PURPOSE

The main purpose of this study is to explore characteristics of patients with chronic kidney disease in tuberous sclerosis (TSC) and to underline differences in clinical characteristics between end-stage renal disease (ESRD) patients and patients in earlier stages of chronic kidney disease.

METHODS

This multicentric, retrospective study included data for 48 patients from seven South-Eastern European countries (Albania, Bosnia and Herzegovina, Croatia, Greece, Montenegro, Serbia, Slovenia) in the period from February to August 2020. Researchers collected data from local and national nephrological and neurological registries and offered clinical and laboratory results from medical histories in follow-up periods.

RESULTS

This study enrolled 48 patients with a median age of 32.3 years (range, 18-46 years), and predominant female gender (60.45%). The percentage of patients with chronic kidney disease (CKD) diagnosis of the total number of patients was 66.90%, with end-stage renal disease development in 39.6%. The most prevalent renal lesions leading to chronic kidney disease were angiomyolipomas (AMLs) in 76.6%, while multiple renal cysts were present in 42.6% of patients. Nephrectomy was performed in 43% of patients, while the mTOR inhibitors were used in 18 patients (37.5%). The majority of patients had cutaneous manifestations of tuberous sclerosis-83.30% had hypomelanotic cutaneous lesions, and 68.80% had angiofibromas. Multiple retinal nodular hamartomas and "confetti" skin lesions were more frequent in end-stage renal disease (ESRD) than in patients with earlier stages of chronic kidney disease (p-0.033 and 0.03, respectively).

CONCLUSION

Our study has also shown that retinal hamartomas and "confetti" skin lesions are more frequent in end-stage renal diseases (ESRD) patients than in other chronic kidney disease (CKD) patients. Usage of mTOR inhibitors can also reduce the number of complications and associated with tuberous sclerosis, such as dermatological manifestations and retinal hamartoma, which are more common in the terminal stage of chronic kidney disease.

Mosaicism in tuberous sclerosis complex: Lowering the threshold for clinical reporting

Tuberous sclerosis complex (TSC) is a multi-system genetic disorder. Most patients have germline mutations in TSC1 or TSC2 but, 10%-15% patients do not have TSC1/TSC2 mutations detected on routine clinical genetic testing. We investigated the contribution of low-level mosaic TSC1/TSC2 mutations in unsolved sporadic patients and families with TSC. Thirty-one sporadic TSC patients negative on routine testing and eight families with suspected parental mosaicism were sequenced using deep panel sequencing followed by droplet digital polymerase chain reaction. Pathogenic variants were found in 22/31 (71%) unsolved sporadic patients, 16 were mosaic (median variant allele fraction [VAF] 6.8% in blood) and 6 had missed germline mutations. Parental mosaicism was detected in 5/8 families (median VAF 1% in blood). Clinical testing laboratories typically only report pathogenic variants with allele fractions above 10%. Our findings highlight the critical need to change laboratory practice by implementing higher sensitivity assays to improve diagnostic yield, inform patient management and guide reproductive counseling.

Efficacy and Safety of Topical Mechanistic Target of Rapamycin Inhibitors for Facial Angiofibromas in Patients with Tuberous Sclerosis Complex: A Systematic Review and Network Meta-Analysis

Previous studies have suggested that the topical mechanistic target of rapamycin (mTOR) inhibitors may be effective in treating facial angiofibromas in patients with tuberous sclerosis complex (TSC). Various concentrations of topical sirolimus for TSC have been tested, but their comparative efficacy and safety remained unclear. To assess the effects of topical mTOR inhibitors in treating facial angiofibromas, we conducted a systematic review and network meta-analysis (NMA) and searched MEDLINE, Embase, and Cochrane Library for relevant randomized controlled trials on 14 February 2022. The Cochrane Collaboration tool was used to assess the risk of bias of included trials. Our outcomes were clinical improvement and severe adverse events leading to withdrawal. We included three trials on 261 TSC patients with facial angiofibromas. The NMA found when compared with placebo, facial angiofibromas significantly improved following the application of various concentrations of topical sirolimus (risk ratio being 3.87, 2.70, 4.43, and 3.34 for 0.05%, 0.1%, 0.2%, and 1%, respectively). When compared with placebo, all concentrations of topical sirolimus did not differ in severe adverse events leading to withdrawal. The ranking analysis suggested topical sirolimus 0.2% as the most effective drug. In conclusion, topical sirolimus 0.05–1% are effective and safe in treating facial angiofibromas in patients with TSC, with topical sirolimus 0.2% being the most effective.

Prevalence of thoracoabdominal imaging findings in tuberous sclerosis complex

Background

Tuberous sclerosis complex (TSC) results in neurodevelopmental phenotypes, benign tumors, and cysts throughout the body. Recent studies show numerous rare findings in TSC. Guidelines suggest routine abdominal and chest imaging to monitor these thoracoabdominal findings, but imaging is not uniformly done across centers. Thus, the prevalence of many findings is unknown. To answer this, we categorized the clinical reads of 1398 thoracoabdominal scans from 649 patients of all ages in the Cincinnati Children’s Hospital TSC Repository Database.

Results

Typical TSC findings were present in many patients: kidney cysts (72%), kidney fat-containing angiomyolipomas (51%), kidney lipid-poor angiomyolipomas (27%), liver angiomyolipomas (19%), and lung nodules thought to represent multifocal micronodular pneumocyte hyperplasia (MMPH) (18%). While many features were more common in TSC2 patients, TSC1 patients had a higher prevalence of MMPH than TSC2 patients (24% versus 13%, p = 0.05). Many rare findings (e.g., lymphatic malformations and liver masses) are more common in TSC than in the general population. Additionally, most thoracoabdominal imaging findings increased with age except kidney cysts which decreased, with the 0–10 years age group having the highest percentage (69% 0–10 years, 49% 10–21 years, 48% 21 + years, p < 0.001). Finally, in our population, no patients had renal cell carcinoma found on abdominal imaging.

Conclusions

These results show that regular thoracoabdominal scans in TSC may show several findings that should not be ignored or, conversely, over-reacted to when found in patients with TSC. Female sex, TSC2 mutation, and age are risk factors for many thoracoabdominal findings. The data suggest novel interactions of genetic mutation with pulmonary nodules and age with renal cysts. Finally, in agreement with other works, these findings indicate that several rare thoracoabdominal imaging findings occur at higher rates in the TSC population than in the general population. This work supports obtaining detailed thoracoabdominal imaging in patients with TSC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-022-02277-x.

The Genetics and Diagnosis of Pediatric Neurocutaneous Disorders: Neurofibromatosis and Tuberous Sclerosis Complex

Neurofibromatosis (NF) and tuberous sclerosis complex (TSC) are the two most common neurocutaneous disorders, both transmitted as autosomal dominant or, in the case of NF, also as a mosaic condition. The causative genetic mutations in these neurocutaneous disorders can lead to benign skin changes or uninhibited growth and proliferation in multiple organ systems due to the loss of tumor suppression in mitogen-activated protein kinase and mammalian target of rapamycin signaling pathways. Common clinical features in NF include pigmented lesions, known as café au lait patches, neurofibromas, intertriginous freckles (Crowe's sign), and benign fibrous growths, such as hamartomas in multiple organ systems. Common clinical features in TSC include hypopigmented macules, known as ash leaf spots, in addition to neurologic sequelae, such as autism, seizures, and developmental delays. Advances in genetic sequencing technologies have allowed an exponential expansion in the understanding of NF and TSC. Consensus criteria have been established for both diagnoses that can be confirmed in most cases through gene testing. Once diagnosed, the clinical and diagnostic value of disease-specific surveillance include early identification of benign and malignant tumors. Genetic counseling is important for informed reproductive decision-making for patients and at-risk family members. The improvement in understanding of pathways of pathogenic disease development and oncogenesis in both conditions have produced a new series of therapeutic options that can be used to control seizures and tumor growth. Tremendous advances in life expectancy and quality of life are now a reality due to early introduction of seizure control and novel medications. While we lack cures, early institution of interventions, such as seizure control in tuberous sclerosis, appears to be disease-modifying and holds immense promise to offer patients better lives.

TSC2 somatic mosaic mutation, including extra-tumor tissue, may be the developmental cause of solitary subependymal giant cell astrocytoma

PURPOSE

Subependymal giant cell astrocytomas (SEGAs) are tumors that usually arise in the wall of one or the other lateral ventricle near a foramen of Monro, most often on a background of tuberous sclerosis complex (TSC). TSC has a variety of clinical manifestations caused by germline mutations of the TSC complex subunit 1 or 2 (TSC1, TSC2) genes. SEGAs without clinical manifestations of TSC are termed solitary SEGAs, which are hypothesized to be caused by tumor-only TSC1/2 mutations, or "forme fruste" of TSC with somatic mosaic mutations. However, it is difficult to distinguish between the two. Here, we report three patients with genetically investigated solitary SEGAs and review this rare manifestation.

METHODS

SEGA was completely removed in two patients and partially removed in one. Genetic analyses were performed on the tumor tissue and on peripheral blood via DNA microarray, reverse-transcriptase polymerase chain reaction, and next-generation sequencing with ultra-deep sequencing of mutation points.

RESULTS

All three patients had tumors with TSC2 somatic mutations and loss of heterozygosity (LOH). In one patient, the same TSC2 mutation was also detected in 1% of leukocytes in his blood. The tumors did not recur, and clinical manifestations of TSC did not develop during the 4-year follow-up.

CONCLUSIONS

The genetic cause of solitary SEGAs may be a TSC2 mutation with LOH. In patients with solitary SEGA, mosaic mutations may present in other organs, and TSC may clinically manifest later in life; therefore, patients should be followed up for prolonged periods.

Hyponatremia: A Tip of the Iceberg in the Late Diagnosis of Tuberous Sclerosis Associated With Lymphangioleiomyomatosis

Tuberous sclerosis (TS) is a rare, autosomal dominant, multisystem genetic disease that causes multiple benign tumors in the brain and other vital organs. Rarely, it can be associated with lymphangioleiomyomatosis (LMA) that is characterized by the proliferation of immature smooth muscle cells in the walls of the airways, venules, and lymphatic vessels in the lung. Here, we present the case of a 44-year-old intellectually disabled woman with a history of marked polydipsia who presented to the emergency department with persistent vomiting. She was hemodynamically stable and did not have any fever. The analytical study showed severe and symptomatic hyponatremia. On physical examination, multiple skin lesions compatible with angiofibromas were noted and the diagnosis of TS was made (confirmed with the genetic study). The multiorgan study documented the presence of multiple cystic images in the lung parenchyma associated with LMA. The aim of this case report is to highlight the importance of targeting cutaneous lesions for a rapid diagnosis of this pathology and to identify the etiology of a severe (symptomatic) ionic disorder and referral to a multidisciplinary team.

Bilateral renal angiomyolipomas in tuberous sclerosis

Background

Tuberous sclerosis complex (TSC) is a rare genetic disorder characterized by benign hamartomas in multiple organs of the body. Renal angiomyolipomas (AML) are commonly associated with TSC. They are mostly asymptomatic. But large and rapidly growing AMLs with the presence of an aneurysm cause symptoms and pose a life-threatening risk for hemorrhage.

Case presentation

Our patient is a 25-year-old female who presented to us as an undiagnosed case of tuberous sclerosis having a large abdominal mass. She fulfilled the clinical criteria required for the diagnosis of TSC. The CT scan revealed an 18 × 13 × 33 cm fat-containing lesion in the right kidney with an adjacent aneurysm measuring around 16 cm in diameter. Due to the large size of the AML and associated aneurysm, surgical exploration was mandated. On the contralateral kidney, multiple contrast-enhancing soft-tissue densities were present that appeared suspicious on radiology. So a percutaneous biopsy of those lesions was done. Fortunately, it had the same histopathology as an Angiomyolipoma. Nephrectomy of the right-sided kidney with AML has been done. The left-sided lesions that are less than 2 cm and asymptomatic are kept on close surveillance. Any change in size will prompt therapy with mTOR inhibitors.

Conclusion

When dealing with bilateral renal AML, it is important to adopt a conservative approach. When intervention is indicated, the least invasive strategy should be sought and enacted. Radical surgery should be the last resort.

Risk Factors Associated with Refractory Epilepsy in Patients with Tuberous Sclerosis Complex: A Systematic Review

BACKGROUND

Epilepsy affects 70-90% of patients with tuberous sclerosis complex (TSC). In one-third of them, the seizures become refractory to treatment. Drug-resistant epilepsy (DRE) carries a significant educational, social, cognitive, and economic burden. Therefore, determining risk factors that increase the odds of refractory seizures is needed. We reviewed current data on risk factors associated with DRE in patients with tuberous sclerosis.

METHODS

The review was performed according to the PRISMA guidelines. Embase, Cochrane Library, MEDLINE, and ClinicalTrial.gov databases were searched. Only full-text journal articles on patients with TSC which defined risk factors related to DRE were included.

RESULTS

Twenty articles were identified, with a cohort size between 6 and 1546. Seven studies were prospective. Three factors appear to significantly increase DRE risk: TSC2 mutation, infantile spasms, and a high number of cortical tubers.

CONCLUSIONS

A proper MRI and EEG monitoring, along with genetic testing, and close observation of individuals with early onset of seizures, allow identification of the patients at risk of DRE.

Inherited Developmental and Epileptic Encephalopathies

Epileptic encephalopathies often have a genetic etiology. The epileptic activity itself exerts a direct detrimental effect on neurodevelopment, which may add to the cognitive impairment induced by the underlying mutation (“developmental and epileptic encephalopathy”). The focus of this review is on inherited syndromes. The phenotypes of genetic disorders affecting ion channels, metabolic signalling, membrane trafficking and exocytosis, cell adhesion, cell growth and proliferation are discussed. Red flags suggesting family of genes or even specific genes are highlighted. The knowledge of the phenotypical spectrum can indeed prompt the clinician to suspect specific etiologies, expediting the diagnosis.

Tuberous sclerosis complex-lymphangioleiomyomatosis involving several visceral organs: A case report

BACKGROUND

Lymphangioleiomyomatosis (LAM) is a rare cystic lung disease characterized by the proliferation, metastasis, and infiltration of smooth muscle cells in the lung and other tissues, which can be associated with tuberous sclerosis complex (TSC). The disorder of TSC has a variable expression, and there is great phenotypic variability.

CASE SUMMARY

A 32-year-old Chinese woman with a history of multiple renal angioleiomyolipoma presented with a productive cough persisting for over 2 wk. High-resolution chest computed tomography revealed interstitial changes, multiple pulmonary bullae, bilateral pulmonary nodules, and multiple fat density areas of the inferior mediastinum. Conventional and contrast ultrasonography revealed multiple high echogenic masses of the liver, kidneys, retroperitoneum, and inferior mediastinum. These masses were diagnosed as angiomyolipomas. Pathology through thoracoscopic lung biopsy confirmed LAM. Furthermore, high-throughput genome sequencing of peripheral blood DNA confirmed the presence of a heterozygous mutation, c.1831C>T (p.Arg611Trp), of the TSC2 gene. The patient was diagnosed with TSC-LAM.

CONCLUSION

We highlight a rare case of TSC-LAM and the first report of a mediastinum lymphangioleiomyoma associated with TSC-LAM.

Epilepsy in adult patients with tuberous sclerosis complex

OBJECTIVES

Little is known about the evolution of epilepsy in individuals with tuberous sclerosis complex (TSC) in adulthood. This study aims at describing the characteristics of epilepsy in adult TSC patients attending a single multidisciplinary clinic.

MATERIALS AND METHODS

We collected data about epilepsy (age at onset, seizure types, history of infantile spasms (IS), epilepsy diagnosis and outcome), genetic and neuroradiological findings, cognitive outcome and psychiatric comorbidities.

RESULTS

Out of 257 adults with TSC, 183 (71.2%) had epilepsy: 121 (67.2%) were drug-resistant; 59 (32.8%) seizure-free, at a median age of 18 years. 22% of the seizure-free patients (13/59) discontinued medication. Median age at seizure onset was 9 months. Seventy-six patients (41.5%) had a history of IS. TSC2 pathogenic variants (p = 0.018), cortical tubers (p < 0.001) and subependymal nodules (SENs) (p < 0.001) were more frequent in those who developed epilepsy. Cognitive functioning was lower (p < 0.001) and psychiatric disorders more frequent (p = 0.001). We did not find significant differences regarding age, gender, mutation and tubers/SENs in seizure-free vs drug-resistant individuals. Intellectual disability (p < 0.001) and psychiatric disorders (p = 0.004) were more common among drug-resistant patients.

CONCLUSIONS

Epilepsy in TSC can be a lifelong disorder, but one-third of individuals reach seizure freedom by early adulthood. In the long term, age at epilepsy onset has a crucial role in drug resistance and in developing intellectual disability, both in drug-resistant and drug-sensible patients. Patients with drug-refractory seizures tend to develop psychiatric issues, which should be recognized and adequately treated.

Precision medicine in pediatric solid cancers

Despite huge advances in the diagnosis and treatment of pediatric cancers over the past several decades, it remains one of the leading causes of death during childhood in developed countries. The development of new targeted treatments for these diseases has been hampered by two major factors. First, the extremely heterogeneous nature of the types of tumors encountered in this age group, and their fundamental differences from common adult carcinomas, has made it hard to truly get a handle on the complexities of the underlying biology driving tumor growth. Second, a reluctance of the pharmaceutical industry to develop products or trials for this population due to the relatively small size of the 'market', and a too-easy mechanism of obtaining waivers for pediatric development of adult oncology drugs based on disease type rather than mechanism of action, led to significant difficulties in getting access to new drugs. Thankfully, the field has now started to change, both scientifically and from a regulatory perspective, in order to address some of these challenges. In this review, we will examine some of the recent insights into molecular features which make pediatric tumors so unique and how these might represent therapeutic targets; highlight ongoing international initiatives for providing comprehensive, personalized genomic profiling of childhood tumors in a clinically-relevant timeframe, and look briefly at where the field of pediatric precision oncology may be heading in future.

Autism Spectrum Disorder: Signaling Pathways and Prospective Therapeutic Targets

The Autism Spectrum Disorder (ASD) consists of a prevalent and heterogeneous group of neurodevelopmental diseases representing a severe burden to affected individuals and their caretakers. Despite substantial improvement towards understanding of ASD etiology and pathogenesis, as well as increased social awareness and more intensive research, no effective drugs have been successfully developed to resolve the main and most cumbersome ASD symptoms. Hence, finding better treatments, which may act as "disease-modifying" agents, and novel biomarkers for earlier ASD diagnosis and disease stage determination are needed. Diverse mutations of core components and consequent malfunctions of several cell signaling pathways have already been found in ASD by a series of experimental platforms, including genetic associations analyses and studies utilizing pre-clinical animal models and patient samples. These signaling cascades govern a broad range of neurological features such as neuronal development, neurotransmission, metabolism, and homeostasis, as well as immune regulation and inflammation. Here, we review the current knowledge on signaling pathways which are commonly disrupted in ASD and autism-related conditions. As such, we further propose ways to translate these findings into the development of genetic and biochemical clinical tests for early autism detection. Moreover, we highlight some putative druggable targets along these pathways, which, upon further research efforts, may evolve into novel therapeutic interventions for certain ASD conditions. Lastly, we also refer to the crosstalk among these major signaling cascades as well as their putative implications in therapeutics. Based on this collective information, we believe that a timely and accurate modulation of these prominent pathways may shape the neurodevelopment and neuro-immune regulation of homeostatic patterns and, hopefully, rescue some (if not all) ASD phenotypes.

A case of solitary subependymal giant cell astrocytoma with histopathological anaplasia and TSC2 gene alteration

We report a case of subependymal giant cell astrocytoma (SEGA) with anaplastic histological features in a 3-year-old girl. She had no clinical manifestations of tuberous sclerosis complex (TSC) and no relevant family history. A few cases have been reported in which patients with SEGA had no other clinical manifestations of TSC (solitary SEGA). Genetic analysis using a blood sample from the patient showed no germline alterations in TSC1 or TSC2 genes, while the tumor tissue exhibited loss of heterozygosity (LOH) in TSC2. SEGAs are benign, slowly growing tumors that rarely have significant mitotic activity. However, histopathological examination in the present case revealed high mitotic activity and necrosis besides the typical large plump cells arranged in sheets. This may be the first genetically proven case of a solitary SEGA with histopathological anaplastic features. In this report, we reviewed solitary SEGAs and histopathological malignancy in SEGA.

A case of subependymal giant cell astrocytoma without tuberous sclerosis complex and review of the literature

Subependymal giant cell astrocytoma (SEGA) is a World Health Organization (WHO) grade I tumor most commonly seen in the context of the underlying tuberous sclerosis complex (TSC). SEGA in the absence of TSC is exceedingly rare. We report the youngest known case of SEGA in the absence of genetic or phenotypic evidence of TSC with a 10-year follow-up. We discuss the literature surrounding isolated SEGA including an approach to diagnosis, management, and prognosis.

Neuroimaging and genetic characteristics of malformation of cortical development due to mTOR pathway dysregulation: clues for the epileptogenic lesions and indications for epilepsy surgery

Introduction: Malformation of cortical development (MCD) is strongly associated with drug-resistant epilepsies for which surgery to remove epileptogenic lesions is common. Two notable technological advances in this field are identification of the underlying genetic cause and techniques in neuroimaging. These now question how presurgical evaluation ought to be approached for 'mTORpathies.'Area covered: From review of published primary and secondary articles, the authors summarize evidence to consider focal cortical dysplasia (FCD), tuber sclerosis complex (TSC), and hemimegalencephaly (HME) collectively as MCD mTORpathies. The authors also consider the unique features of these related conditions with particular focus on the practicalities of using neuroimaging techniques currently available to define surgical targets and predict post-surgical outcome. Ultimately, the authors consider the surgical dilemmas faced for each condition.Expert opinion: Considering FCD, TSC, and HME collectively as mTORpathies has some merit; however, a unified approach to presurgical evaluation would seem unachievable. Nevertheless, the authors believe combining genetic-centered classification and morphologic findings using advanced imaging techniques will eventually form the basis of a paradigm when considering candidacy for early surgery.

Current concepts on ocular vascular abnormalities in the phakomatoses

BACKGROUND

Neurofibromatosis, Von Hippel Lindau disease, and tuberous sclerosis complex are classified under the term phakomatoses. They are characterized by ocular vascular abnormalities such as vascular tortuosity, corkscrew retinal vessel configuration, moyamoya-like aspect, microaneurysms, hemangioblastomas, and focal sheathing of retinal arteries, possibly due to abnormal formation, migration, and differentiation of neural crest cells. These alterations can be the first sign or the hallmark of disease and can be related to vasoproliferative tumors.

PURPOSE

Novel imaging technologies in ophthalmology, such as near-infrared reflectances and spectral domain optical coherence tomography, have improved our knowledge in the diagnosis of these pathologies. Previously undetected macular vascular alterations have been reported in phakomatoses using optical coherence tomography angiography. This review will summarize the ophthalmic vascular abnormalities and novel imaging methods in the phakomatoses.

CONCLUSION

Active research is being led into the ophthalmic management of these conditions and their complications, and owing to elevated vascular endothelial growth factor production from hemangioblastoma, hamartoma, and retinal vascular proliferative tumors, increasing interest in this line of therapy has been conducted although research is still ongoing in this area.

Deciphering the roles of glycogen synthase kinase 3 (GSK3) in the treatment of autism spectrum disorder and related syndromes

Autism spectrum disorder (ASD) is a complex and multifactorial neurodevelopmental disorder characterized by the presence of restricted interests and repetitive behaviors besides deficits in social communication. Syndromic ASD is a subset of ASD caused by underlying genetic disorders, most commonly Fragile X Syndrome (FXS) and Rett Syndrome (RTT). Various mutations and consequent malfunctions in core signaling pathways have been identified in ASD, including glycogen synthase kinase 3 (GSK3). A growing body of evidence suggests a key role of GSK3 dysregulation in the pathogenesis of ASD and its related disorders. Here, we provide a synopsis of the implication of GSK3 in ASD, FXS, and RTT as a promising therapeutic target for the treatment of ASD.

Tuberous sclerosis complex: A multisystem disorder

ABSTRACT

Tuberous sclerosis complex (TSC) is a genetic disorder that affects multiple organ systems but often goes unrecognized, and a delay in diagnosis can lead to multiple complications. Healthcare professionals should be educated on the many signs and symptoms associated with the disorder, know how to treat them symptomatically, and recommend routine screening to assess for complications. Correctly identifying, diagnosing, and treating TSC can give patients a better quality of life and prevent further complications associated with the disorder.

Tuberous Sclerosis Complex: Early Screening and Infant Outcome in NICU

OBJECTIVE

We describe the clinical and genetic features, drug use and neuropsychiatric disorders of infants diagnosed with tuberous sclerosis complex (TSC) within 3 months of age at a neonatal intensive care unit (NICU) to better understand the different outcomes from early screening.

METHODS

In this retrospective study, we consisted of 42 infants with a definitive TSC diagnosis by genetic criteria (TSC1 = 8, TSC2 = 34). The different phenotypes and outcomes between patients with TSC1 and TSC2 mutations were analyzed.

RESULTS

The most common initial presenting features of TSC were cortical tubers on magnetic resonance imaging (50%), hypomelanotic macules on skin (47.61%) and spasm (42.85%), when they were diagnosed. Following disease progression to time of follow-up 1 year later, we found that the rate of epilepsy increased from 42.85% to 75.61% and that of cardiac rhabdomyoma increased from 28.57% to 43.9%. The median age at first presentation was 7.84 ± 1.88 months. We also found that 54.83% of patients on medication were seizure free for over 1 year, and that 43.9% of patients have intellectual disability. In total, 42 variants of TSC were detected, including 12 novel variants. We found no evidence of an association between different clinical features and their outcomes among patients with different gene mutations.

CONCLUSION

Early diagnosis of TSC in NICU opens a window of opportunity for early, more effective treatment of epilepsy as well as reduces the risk of neurological conditions.

Update on the genetics of keratoconus

In the past few years we have seen a great acceleration of discoveries in the field of keratoconus including new treatments, diagnostic tools, genomic and molecular determinants of disease risk. Recent genome-wide association studies (GWAS) of keratoconus cases and population wide studies of variation in central corneal thickness and in corneal biomechanical properties confirmed already identified genes and found many new susceptibility variants and biological pathways. Recent findings in genetic determinants of familial keratoconus revealed functionally important variants and established first mouse model of keratoconus. Latest transcriptomic and expression studies started assessing novel non-coding RNA targets in addition to identifying tissue specific effects of coding genes. First genomic insights into better prediction of treatment outcomes are bringing the advent of genomic medicine into keratoconus clinical practice.

Genetics of tuberous sclerosis complex: an update

PURPOSE

To review the current genetic aspects of tuberous sclerosis complex.

METHODS

Review of the literature.

RESULTS

Tuberous sclerosis complex (TSC), a long known childhood-onset monogenic disorder, characterized by hamartoma formation affecting mainly the brain, heart, kidney, lung, and skin, is associated with a high morbidity burden and risk of a reduced life span. The identification of TSC1 and TSC2, as tumor suppressor genes causative of the disorder, led to the elucidation of the mammalian target of rapamycin complex 1 (mTORC1) signaling pathway and its pivotal role in the pathogenesis of hamartoma formation. This knowledge was translated into standard clinical practice with the discovery of rapamycin, and additional analogues, as inhibitors of mTORC1.

CONCLUSION

Next-generation sequencing was proven to be fundamental to drive research of tumorigenesis in TSC, hopefully leading to new therapeutic options in the future.

Mutation Spectrum of Tuberous Sclerosis Complex Patients in Indian Population

Tuberous sclerosis complex (TSC) is a multiorgan disorder characterized by formation of hamartomas and broad phenotypic spectrum including seizures, mental retardation, renal dysfunction, skin manifestations and brain tubers. It is inherited in an autosomal dominant pattern, caused due to mutation in either TSC1 or TSC2 genes. Seizures are one of the major presenting symptoms of TSC that helps in early diagnosis. The present study describes the mutation spectrum in TSC1 and TSC2 genes in TSC patients and their association with neurocognitive-behavioral phenotypes. Ninety-eight TSC patients were enrolled for TSC genetic testing after detailed clinical and neurobehavioral assessment. Large genomic rearrangement testing was performed by multiplex ligation-dependent probe amplification (MLPA) technique for all cases and Sanger sequencing was performed for MLPA negative cases. Large rearrangements were identified in approximately 1% in TSC1 and 14.3% in TSC2 genes. The present study observed the presence of duplications in two (2%) cases, both involving TSC2/PKD1 contiguous genes which to the best of our knowledge is reported for the first time. 8.1% of small variants were identified in the TSC1 gene and 85.7% in TSC2 gene, out of which 23 were novel variations and no variants were found in six (6.1%) cases. This study provides a representative picture of the distribution of variants in the TSC1 and TSC2 genes in Indian population along with the detailed assessment of neurological symptoms. This is the largest cohort study from India providing an overview of comprehensive clinical and molecular spectrum.

Brain Proteomic Profiling in Intractable Epilepsy Caused by TSC1 Truncating Mutations: A Small Sample Study

Tuberous sclerosis complex (TSC) is a genetic disease characterized by seizures, mental deficiency, and abnormalities of the skin, brain, kidney, heart, and lungs. TSC is inherited in an autosomal dominant manner and is caused by variations in either the TSC1 or TSC2 gene. TSC-related epilepsy (TRE) is the most prevalent and challenging clinical feature of TSC, and more than half of the patients have refractory epilepsy. In clinical practice, we found several patients of intractable epilepsy caused by TSC1 truncating mutations. To study the changes of protein expression in the brain, three cases of diseased brain tissue with TSC1 truncating mutation resected in intractable epilepsy operations and three cases of control brain tissue resected in craniocerebral trauma operations were collected to perform protein spectrum detection, and then the data-independent acquisition (DIA) workflow was used to analyze differentially expressed proteins. As a result, there were 55 up- and 55 down-regulated proteins found in the damaged brain tissue with TSC1 mutation compared to the control. Further bioinformatics analysis revealed that the differentially expressed proteins were mainly concentrated in the synaptic membrane between the patients with TSC and the control. Additionally, TSC1 truncating mutations may affect the pathway of amino acid metabolism. Our study provides a new idea to explore the brain damage mechanism caused by TSC1 mutations.

A case of surgically resected cardiac rhabdomyoma with progressive left ventricular outflow tract obstruction

Cardiac rhabdomyoma is the most prevalent cardiac tumors in the pediatric population, in close association with tuberous sclerosis complex. It is usually detected antenatally or postnatally by echocardiography. Clinical presentations depend greatly on the size and position of the tumor mass. Interestingly, rhabdomyoma has a propensity to regress spontaneously and is not usually operated upon, unless the patient becomes hemodynamically compromised. Herein, we report an unusual case of surgically treated cardiac rhabdomyoma in a baby boy presented at birth with a progressive enlarging intraventricular mass, complicated with left ventricular outflow tract obstruction 7 weeks later. Histopathological examination of the intracardiac mass revealed sheets of tumor cells with spider-like morphology (known as "spider cells"), confirmed the diagnosis of rhabdomyoma. Close disease monitoring of patient's hemodynamic status in a newly diagnosed cardiac rhabdomyoma is inevitable as the tumor, although rare, may progress.

Bone tissue and mineral metabolism in hereditary endocrine tumors: clinical manifestations and genetic bases

Inherited endocrine tumors are neoplasms of endocrine cells, transmitted via autosomal dominant germinal mutations. They present in two different forms: non-syndromic (patient has a single affected endocrine organ during his/her lifetime) or syndromic forms (multiple tumors in endocrine and non-endocrine organs during his/her lifetime).In addition to their common tumoral manifestations, many of these diseases present clinical affection of bone tissues and/or mineral metabolism, both as secondary complications of primary tumors and as primary defects due to genetic mutation. To date, few studies have documented these bone complications, and there are no systematic reviews in this area.We present a revision of medical literature about skeletal and mineral metabolism affections in inherited endocrine tumor syndromes, and studies, in cells and animal models, investigating the direct role of some genes, whose mutations are responsible for the development of endocrine tumors, in the regulation of bone and mineral metabolism.

[Hereditary kidney cancers: The pathologist's view in 2020]

Hereditary predispositions to adult kidney tumors involve around 5% of tumors and include a dozen of autosomal dominant syndromes. The most frequent tumors encountered in these setting are clear cell renal cell carcinomas, papillary renal cell carcinomas, chromophobe renal cell carcinomas and angiomyolipomas. Their detection is essential in order to adapt individual care and perform genetic screening of at-risk relatives, especially in the national french network PREDIR, labeled by the National Cancer Institute and dedicated to hereditary predispositions to kidney tumors. Targeted genetic analysis, which was guided in particular by the renal tumor subtype, has recently evolved into genetic analysis using panels of genes. Pathologist contribution's remains however central in the diagnosis of hereditary forms since we currently have immunohistochemical biomarkers that allow us to diagnose two specifically hereditary entities: hereditary leiomyomatosis and renal cell carcinoma associated-renal cell carcinoma, associated with a loss of fumarate hydratase and succinate dehydrogenase-deficient renal cell carcinoma associated with a loss of succinate deshydrogenase B expression. These diagnoses must however be confirmed by the identification of pathogenic germline variation in the corresponding genes. Improvement of kidney tumors characterization has also lead to identify new subtypes, expanding the algorithm of renal tumors associated with hereditary setting. Here we aim to review all subtypes of adult renal tumors encountered in predisposition syndromes.

Investigation of quantitative susceptibility mapping in diagnosis of tuberous sclerosis complex and assessment of associated brain injuries at 1.5 Tesla

BACKGROUND AND AIM

Tuberous sclerosis complex (TSC) is a rare disease with serious clinical consequences such as mental deficiency and epilepsy. The pathological changes of TSC include demyelination and subependymal calcified nodules. Quantitative susceptibility mapping (QSM) is a newly developed imaging technique which is capable of quantitatively measuring the susceptibility induced by iron deposition, calcification, and demyelination. The aim of this study was to investigate the use of QSM in detecting the subependymal nodules and assessing brain tissue injuries induced by cortical/subcortical tubers in TSC patients.

MATERIALS AND METHODS

Twelve clinically confirmed TSC patients and fifteen gender- and age-matched healthy subjects underwent measurement with conventional magnetic resonance imaging (MRI) sequences, diffusion tensor imaging (DTI), and QSM. The TSC patients further underwent a computed tomography (CT) scan. Considering CT as the ground truth, the detection rates of subependymal nodules using conventional MRI and QSM were compared by the paired Chi-square test, and the sensitivity and specificity were computed. The Bland-Altman test and independent t-test were performed to compare the susceptibility of cortical/subcortical regions from QSM and fractional anisotropy (FA) values from DTI between the patient and control groups, Pearson correlation was performed to examine the correlation between the susceptibility and FA values.

RESULTS

QSM was better in detecting subependymal calcified nodules compared to conventional MR sequences (X ²=40.18, P<0.001), QSM achieved a significantly higher sensitivity of 98.3% and a lower specificity of 50%, which was compared with conventional MR sequences (46.7% and 75%, respectively). The susceptibility value of cortical/subcortical tubers in TSC patients was significantly higher than those in the control group (t=9.855, P<0.001), while FA value was lower (t=-8.687, P<0.001). Pearson correlation test revealed a negative correlation between susceptibility and FA values in all participants (r=-0.65, P<0.001).

CONCLUSIONS

QSM had a similar ability in TSC compared to CT and DTI. QSM may provide valuable complementary information to conventional MRI imaging and may simplicity imaging of patients with TSC.

RELEVANCE FOR PATIENTS

This study shows the feasibility of QSM to detect subependymal calcified nodules. It may provide quantitative information of white matter damage of tuberous sclerosis patients.

Upregulation of 6-phosphofructo-2-kinase (PFKFB3) by hyperactivated mammalian target of rapamycin complex 1 is critical for tumor growth in tuberous sclerosis complex

Tuberous sclerosis complex (TSC) is an autosomal dominant disease characterized by the benign tumor formation in multiple organs. The main etiology of TSC is the loss-of-function mutation of TSC1 or TSC2 gene, which leads to aberrant activation of mammalian target of rapamycin complex 1 (mTORC1). In this research, we found a significant increase of 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3) expression in Tsc1-/- and Tsc2-/- mouse embryonic fibroblasts (MEFs) compared with the control cells. Inhibition of mTORC1 led to a dramatic decrease of PFKFB3 expression, indicating PFKFB3 regulation by mTORC1. Moreover, suppression of mTORC1 inhibited the expression of PFKFB3 in rat uterine leiomyoma-derived Tsc2-null ELT3 cells and human tumor cells. Furthermore, we identified hypoxia-inducible factor 1α (HIF-1α) as a mediator transmitting the signal from mTORC1 to PFKFB3. Depletion of PFKFB3 inhibited proliferation and tumorigenicity of Tsc1- or Tsc2-deficient cells. In addition, combination of rapamycin with PFK15, a PFKFB3 inhibitor, exerts a stronger inhibitory effect on cell proliferation of Tsc1- or Tsc2-null MEFs than treatment with single drug. We conclude that loss of TSC1 or TSC2 led to upregulated expression of PFKFB3 through activation of mTORC1/HIF-1α signaling pathway and co-administration of rapamycin and PFK15 may be a promising strategy for the treatment of TSC tumors as well as other hyperactivated mTORC1-related tumors.

TSC patient-derived isogenic neural progenitor cells reveal altered early neurodevelopmental phenotypes and rapamycin-induced MNK-eIF4E signaling

Background

Tuberous sclerosis complex (TSC) is a neurodevelopmental disorder with frequent occurrence of epilepsy, autism spectrum disorder (ASD), intellectual disability (ID), and tumors in multiple organs. The aberrant activation of mTORC1 in TSC has led to treatment with mTORC1 inhibitor rapamycin as a lifelong therapy for tumors, but TSC-associated neurocognitive manifestations remain unaffected by rapamycin.

Methods

Here, we generated patient-specific, induced pluripotent stem cells (iPSCs) from a TSC patient with a heterozygous, germline, nonsense mutation in exon 15 of TSC1 and established an isogenic set of heterozygous (Het), null and corrected wildtype (Corr-WT) iPSCs using CRISPR/Cas9-mediated gene editing. We differentiated these iPSCs into neural progenitor cells (NPCs) and examined neurodevelopmental phenotypes, signaling and changes in gene expression by RNA-seq.

Results

Differentiated NPCs revealed enlarged cell size in TSC1-Het and Null NPCs, consistent with mTORC1 activation. TSC1-Het and Null NPCs also revealed enhanced proliferation and altered neurite outgrowth in a genotype-dependent manner, which was not reversed by rapamycin. Transcriptome analyses of TSC1-NPCs revealed differentially expressed genes that display a genotype-dependent linear response, i.e., genes upregulated/downregulated in Het were further increased/decreased in Null. In particular, genes linked to ASD, epilepsy, and ID were significantly upregulated or downregulated warranting further investigation. In TSC1-Het and Null NPCs, we also observed basal activation of ERK1/2, which was further activated upon rapamycin treatment. Rapamycin also increased MNK1/2-eIF4E signaling in TSC1-deficient NPCs.

Conclusion

MEK-ERK and MNK-eIF4E pathways regulate protein translation, and our results suggest that aberrant translation distinct in TSC1/2-deficient NPCs could play a role in neurodevelopmental defects. Our data showing upregulation of these signaling pathways by rapamycin support a strategy to combine a MEK or a MNK inhibitor with rapamycin that may be superior for TSC-associated CNS defects. Importantly, our generation of isogenic sets of NPCs from TSC patients provides a valuable platform for translatome and large-scale drug screening studies. Overall, our studies further support the notion that early developmental events such as NPC proliferation and initial process formation, such as neurite number and length that occur prior to neuronal differentiation, represent primary events in neurogenesis critical to disease pathogenesis of neurodevelopmental disorders such as ASD.

Mouse Models of Congenital Kidney Anomalies

Congenital anomalies of the kidney and urinary tract (CAKUT) are common birth defects, which cause the majority of chronic kidney diseases in children. CAKUT covers a wide range of malformations that derive from deficiencies in embryonic kidney and lower urinary tract development, including renal aplasia, hypodysplasia, hypoplasia, ectopia, and different forms of ureter abnormalities. The majority of the genetic causes of CAKUT remain unknown. Research on mutant mice has identified multiple genes that critically regulate renal differentiation. The data generated from this research have served as an excellent resource to identify the genetic bases of human kidney defects and have led to significantly improved diagnostics. Furthermore, genetic data from human CAKUT studies have also revealed novel genes regulating kidney differentiation.

Pneumothorax as a Presentation of Tuberous Sclerosis-Associated Lymphangioleiomyomatosis

Tuberous sclerosis complex (TSC) is a rare, autosomal dominant disorder with a recognized phenotypic variability with clinical manifestations developing continuously throughout life. The follow-up of TSC patients is challenging. The authors present a case with a definite diagnosis of TSC with known skin, renal, hepatic and neuropsychiatric involvement, whose diagnosis of TSC-associated lymphangioleiomyomatosis was establish at a late stage after the patient had presented with recurrent pneumothorax. Notwithstanding, mammalian target of rapamycin inhibition therapy was initiated.