The tuberous sclerosis complex: a comprehensive review

Kidney transplantation in patients with tuberous sclerosis complex

BACKGROUND

Tuberous sclerosis complex (TSC) is a disorder of the mammalian target of the rapamycin (mTOR) pathway associated with the development of multisystem tumors, including renal angiomyolipoma (AML). These renal tumors are benign by nature but locally invasive and carry a risk for the progression of chronic kidney disease (CKD) to end stage kidney disease (ESKD). The frequency of subsequent renal transplantation in this population is largely uncharacterized, although single-center data suggests that 5%-15% of adult TSC patients are kidney transplant recipients.

METHODS

This retrospective cohort study utilized United Network for Organ Sharing (UNOS) data. We included candidates waitlisted between 1987 and 2020 for a first kidney transplant with TSC-associated kidney failure. We utilized descriptive statistics to characterize the frequency of first-time kidney transplant waitlisting and transplantation among persons with TSC and the Fine-Gray subdistribution hazard model to evaluate characteristics associated with progression from waitlist.

RESULTS

We identified 200 TSC-associated kidney failure patients within the waitlist cohort. Of these, 12 were pediatric patients. Two-thirds (N = 134) of waitlisted persons were female. One hundred forty patients received a transplant with a median waitlist time of 2 years. Younger age at waitlisting was associated with a greater probability of progressing to transplant (HR 0.98 [95% CI: 0.96-0.99]). 91.8% of kidney transplant recipients survived 1-year post-transplant with a functioning allograft.

CONCLUSIONS

The majority of patients with TSC who are waitlisted for a kidney transplant progress onto transplantation with excellent 1-year post transplant patient and allograft survival.

Popliteal artery aneurysm in a 14-year-old boy with tuberous sclerosis complex

Tuberous sclerosis complex (TSC) is rarely associated with aneurysms. We have described a patient with a popliteal artery aneurysm that was associated with TSC and occlusion of the right posterior tibial artery. The patient underwent aneurysm resection and vein graft replacement, with an uneventful postoperative course and no recurrence at 11 months of follow-up. Patients with TSC could have aneurysms in areas that will not be recognized on abdominal imaging. Physical examination of the lower extremities should be performed owing to the possibility of a popliteal artery aneurysm, and imaging studies should be performed if an aneurysm is suspected.

Endovascular Repair of a Descending Thoracic Aortic Aneurysm in a Pediatric Patient with Tuberous Sclerosis: A Case Report and Review of the Literature

Aortic aneurysm in children is rare, but has been described in the tuberous sclerosis complex (TSC) population. While surgical repair has been utilized as the primary means of intervention, we present the first known case reporting exclusion of a descending thoracic aortic aneurysm with percutaneous covered stent implantation in a pediatric patient with TSC. A review of the literature is also included herein.

Neuroendocrine pancreatic tumor in a patient with dual diagnosis of tuberous sclerosis complex and basement membrane disease: A case report and review of the literature

Tuberous Sclerosis is a complex genetic disease that has well-defined clinical criteria. These criteria don't include pancreatic neuroendocrine tumors. We represent a rare case of a patient, with a non-functioning pancreatic neuroendocrine tumor and concomitant diagnosis of tuberous sclerosis complex, and basement membrane disease. The patient was diagnosed based on typical radiologic findings. We have suggested close monitoring and during follow-up studies, the disease was stable. Interestingly the patient tested negative for Tuberous Sclerosis Complex (TSC), which suggests that she might be a somatic mosaic and the mutation level in blood lymphocytes was below the detection level. Moreover, a heterozygous pathogenic variant p.(Gly774Arg) and a heterozygous likely pathogenic variant p.(Gly1465Asp) were identified in the COL4A4 gene. COL4A4 gene is responsible for causing autosomal dominant basement membrane disease. In this case report, we discuss clinical, radiologic, and genetic aspects of these diseases, as well as optimal treatment and follow-up strategies. Thus, by presenting this case we would like to increase awareness of pancreatic neuroendocrine tumors in TSC and emphasize the need for follow-up monitoring.

Molecular-Genetic Characteristics and Genotype-Phenotype Correlations in Bulgarian Patients with Tuberous Sclerosis Complex

Objective

The aim of the study was to determine the molecular-genetic characteristics of the autosomal dominant systematic disorder Tuberous Sclerosis Complex (TSC1 and TSC2) in Bulgarian patients and to derive some genotype-phenotype correlations.

Material and Methods

In total 42 patients/families with suspected clinical diagnosis of TSC were analyzed. We used direct sequencing and MLPA for the TSC1 and TSC2 gene analysis.

Results

In 38 families (90.5%) we confirmed the suspected clinical diagnosis – 15 with TSC1 (35.7%) and 23 (54.8%) with TSC2. In 4 families (9.5%) pathogenic variants were not found. In all 38 patients with proven diagnosis of TSC, we found 38 different mutations, 15 of which (39%) were detected for the first time by our research group. The mutation “hotspots“ in TSC1 gene are exons 9, 15, 17 and 18, where 73% of the TSC1 mutations are localized, while the TSC2 gene mutation “hotspots“ are exons 13 and 34, with 22% of the mutations situated there. In the TSC2 patients the common clinical findings include subcortical tubers, epilepsy with generalized tonic-clonic seizures, subependymal giant cell astrocytoma, facial angiofibromas, ungual fibromas, cardiac rhabdomyomas and renal angiomyolipomas, while in the TSC1 patients typically cortical tubers, cortical dysplasia and subependymal nodules were registered. In patients with aggressive frameshift and nonsense TSC1 and TSC2 mutations commonly hypomelanotic macules, cortical and subcortical tubers, cortical dysplasia, epilepsy with different types of seizures were found. Renal angiomyolipomas and cysts were detected mainly in patients with large deletions. Shagreen patches and intellectual disability were typically registered in equal degree in patients with frameshift, nonsense and missense mutations.

Conclusion

Although some genotype-phenotype correlations were derived, there is a great inter- and intrafamilial clinical variability in TSC, so it is impossible to predict the course of the disease on the basis of the detected molecular defect. The obtained results helped us to develop a diagnostic algorithm for proper molecular-genetic diagnostics which permits adequate genetic counseling, prophylaxis and treatment in the affected TSC families.

Kidney Imaging Surveillance in Commercially Insured Patients With Tuberous Sclerosis Complex

BACKGROUND

Kidney disease has historically been the primary source of early mortality in adults with tuberous sclerosis complex (TSC). Kidney imaging surveillance promotes early detection of lesions requiring intervention. We describe kidney imaging frequency in relationship to patient-level characteristics for commercially insured patients with TSC in the United States.

METHODS

This retrospective observational study used 2003 to 2016 enrollment and claims data from a de-identified fully insured commercial health insurer. Patients with TSC less than 65 years were included. The patient-level kidney imaging rate was calculated as the number of kidney imaging procedures divided by length of continuous enrollment. A multiple linear regression model was used to determine the relationship between imaging rate and progression of TSC-associated kidney disease, number of specialists seen, and nephrologist care.

RESULTS

At least half of the 70 patients with TSC included in the study were aged 16 years or younger. Over a follow-up period of up to 14 years, the median kidney imaging rate was 0.13 procedures per year with 43% (N = 30) of patients lacking evidence of kidney imaging during the observation period. Imaging frequency increased with progression of TSC-associated kidney disease, more specialists, and nephrologist care (P < 0.05 for all three in regression model).

CONCLUSIONS

A substantial percentage of patients with TSC in the United States are at risk for delayed detection of kidney manifestations due to infrequent kidney imaging surveillance. Multispecialty care, including neurologists, may positively affect kidney surveillance rates.

Desmoplastic fibroma associated with tuberous sclerosis: case report and literature review

Tuberous sclerosis complex (TSC) is an autosomal dominant genetic disorder that affects the skin, brain, kidneys, and other organ systems. It may exhibit a wide spectrum of clinical manifestations. Desmoplastic fibroma (DF) of the jaw is a rare benign myofibroblastic neoplasm. Less than 10 cases of DF associated with TSC have been published previously. We report a new case of a maxillary DF in a 12-year-old girl with TSC. The presentation, diagnostic process, and management of this case are discussed, and the literature is reviewed for the additional cases of DF associated with TSC; 7 previously reported cases are summarized. Small sample size limits conclusions, but there may be differences in the presentations of DF of the jaws in patients with TSC vs those in the general population. DF of the jaws may be a manifestation of TSC, and the authors propose surveillance panoramic radiographs every 2 to 3 years in patients with TSC.

Applying the Lessons of Tuberous Sclerosis: The 2015 Hower Award Lecture

Tuberous sclerosis complex is a dominantly inherited disorder that variably affects the brain, skin, kidneys, heart, and other organs. Its neurological manifestations include epilepsy, autism, cognitive and behavioral dysfunction, and giant cell tumors. A mutation of either TSC1 or TSC2 can cause tuberous sclerosis complex. Their two gene products, hamartin and tuberin, form a physical complex which normally inhibits protein synthesis mediated through the mechanistic target of rapamycin, so a TSC1 or TSC2 mutation results in overactivation of the mechanistic target of rapamycin cascade. In addition to their tumor suppressor roles, TSC1 and TSC2 help to regulate cell size, neuronal migration, axon formation, and synaptic plasticity. Clinical trials of two different the mechanistic target of rapamycin inhibitors have demonstrated substantial improvement of tuberous sclerosis complex-related tumors, and a recent trial also showed a benefit from the mechanistic target of rapamycin inhibitor everolimus in the treatment of refractory epilepsy due to tuberous sclerosis complex. Effective mechanism-based therapy is now available for some manifestations of tuberous sclerosis complex.

Huaier aqueous extract inhibits proliferation and metastasis of tuberous sclerosis complex cell models through downregulation of JAK2/STAT3 and MAPK signaling pathways

Tuberous sclerosis complex (TSC) is a genetic disorder with formation of benign tumors in many different organs. It has attracted increasing attention from researchers to search for therapeutic drugs for TSC patients. Traditional Chinese medicine (TCM) has become an important source for finding antitumor drugs. Trametes robiniophila Μurr. (Huaier) is a kind of officinal fungi in China and has been applied in TCM for approximately 1,600 years. A large number of clinical applications have revealed that Huaier has good antitumor effect. In this study, we have investigated the effects of Huaier aqueous extract on two TSC cell models, including inhibition of proliferation, induction of apoptosis, cell cycle arrest, and anti-metastasis. We demonstrated that Huaier aqueous extract inhibited JAK2/STAT3 and MAPK signaling pathways in a dose-dependent manner. Therefore, based on the low toxicity and the multi-targets of Huaier treatment, Huaier may be a promising therapeutic drug for TSC.

Tuberous sclerosis complex

Tuberous sclerosis complex (TSC) is a neurocutaneous syndrome that can affect the brain, skin, eyes, kidneys, heart, and lungs. TSC alters cellular proliferation and differentiation, resulting in hamartomas of various organs, tumor formation, and altered neuronal migration. The phenotype is highly variable. Most individuals have seizures, commonly including infantile spasms, and there is variable intellectual disability and autism. Neonates can present with cardiac failure due to intracardiac rhabdomyomas. The likelihood of renal angiomyolipomas increases with age, and renal disease is the most common cause of death in adults with TSC. Pulmonary involvement occurs predominantly in women and carries a high morbidity and mortality. TSC is inherited as an autosomal dominant trait, but spontaneous mutations are common. A mutation of either TSC1 on chromosome 9 or TSC2 on chromosome 16 leads to dysfunction of hamartin or tuberin, respectively. These two proteins form a functional complex that modulates the mammalian target of rapamycin (mTOR) pathway. Medications that inhibit mTOR are being used to treat TSC-related tumors, and current studies are investigating whether these agents could alleviate other TSC complications. Consensus statements guide identification and optimal management of many of the TSC-related complications at diagnosis and throughout the lifespan. A multidisciplinary approach is necessary for optimal management of individuals with TSC.

A practice guideline from the American College of Medical Genetics and Genomics and the National Society of Genetic Counselors: referral indications for cancer predisposition assessment

DISCLAIMER

The practice guidelines of the American College of Medical Genetics and Genomics (ACMG) and the National Society of Genetic Counselors (NSGC) are developed by members of the ACMG and NSGC to assist medical geneticists, genetic counselors, and other health-care providers in making decisions about appropriate management of genetic concerns, including access to and/or delivery of services. Each practice guideline focuses on a clinical or practice-based issue and is the result of a review and analysis of current professional literature believed to be reliable. As such, information and recommendations within the ACMG and NSGC joint practice guidelines reflect the current scientific and clinical knowledge at the time of publication, are current only as of their publication date, and are subject to change without notice as advances emerge. In addition, variations in practice, which take into account the needs of the individual patient and the resources and limitations unique to the institution or type of practice, may warrant approaches, treatments, and/or procedures that differ from the recommendations outlined in this guideline. Therefore, these recommendations should not be construed as dictating an exclusive course of management, nor does the use of such recommendations guarantee a particular outcome. Genetic counseling practice guidelines are never intended to displace a health-care provider's best medical judgment based on the clinical circumstances of a particular patient or patient population. Practice guidelines are published by the ACMG or the NSGC for educational and informational purposes only, and neither the ACMG nor the NSGC "approve" or "endorse" any specific methods, practices, or sources of information.Cancer genetic consultation is an important aspect of the care of individuals at increased risk of a hereditary cancer syndrome. Yet several patient, clinician, and system-level barriers hinder identification of individuals appropriate for cancer genetics referral. Thus, the purpose of this practice guideline is to present a single set of comprehensive personal and family history criteria to facilitate identification and maximize appropriate referral of at-risk individuals for cancer genetic consultation. To develop this guideline, a literature search for hereditary cancer susceptibility syndromes was conducted using PubMed. In addition, GeneReviews and the National Comprehensive Cancer Network guidelines were reviewed when applicable. When conflicting guidelines were identified, the evidence was ranked as follows: position papers from national and professional organizations ranked highest, followed by consortium guidelines, and then peer-reviewed publications from single institutions. The criteria for cancer genetic consultation referral are provided in two formats: (i) tables that list the tumor type along with the criteria that, if met, would warrant a referral for a cancer genetic consultation and (ii) an alphabetical list of the syndromes, including a brief summary of each and the rationale for the referral criteria that were selected. Consider referral for a cancer genetic consultation if your patient or any of their first-degree relatives meet any of these referral criteria.

Monoallelic germline TSC1 mutations are permissive for T lymphocyte development and homeostasis in tuberous sclerosis complex individuals

Germline and somatic biallelic mutations of the Tuberous sclerosis complex (TSC) 1 and TSC2 gene products cause TSC, an autosomal dominant multifocal hamartomatosis with variable neurological manifestations. The consequences of TSC1 or TSC2 loss in cells of hematopoietic origin have recently started to be unveiled in mice and showed to hinder the development of proper T cell immunity. To date, the consequences of germline TSC1 mutations and/or its loss in mature human T cells remain to be determined. To address these issues, we analyzed subset representation, phenotype and responsiveness to mitogens in T cells from patients with inherited monoallelic TSC1 mutations, and induced shRNA-mediated TSC1 down-regulation in primary and transformed human T cells. We report that, the distribution of peripheral CD4 and CD8 T cell subsets, their cytokine-secretion profile, and responsiveness to in vitro stimulation were largely preserved in TSC subjects with monoallelic TSC1 germline mutations when compared to healthy controls. Sufficient levels of hamartin and tuberin and proper control of mTOR-dependent signaling in primary T cells from TSC subjects best explained this. In contrast, shRNA-induced down-regulation of TSC1, likely mimicking biallelic inactivation of TSC1, compromised hamartin and tuberin expression and mTORC2/AKT/FoxO1/3 signaling causing both primary and transformed T cells to die by apoptosis. Thus, our results indicate that, while one functional TSC1 allele preserves human T lymphocytes development and homeostasis, TSC1 acute down-regulation is detrimental to the survival of both primary and transformed T cells.

Histomorphologic and Immunohistochemical Characterization of a Cardiac Purkinjeoma in a Bearded Seal (Erignathus barbatus)

The most common cardiac tumors of heart muscle are rhabdomyomas, solitary or multiple benign tumors of striated muscle origin. While cardiac rhabdomyomas are well described in human medical literature, limited information depicting the occurrence of cardiac rhabdomyomas in veterinary species exists. A case of multiple firm white nonencapsulated nodules in the heart of a bearded seal is described. Microscopic findings included cytoplasmic vacuolization with formation of spider cells, glycogen vacuoles, and striated myofibrils. These cells expressed immunoreactivity for neuron-specific enolase and protein gene product 9.5, a marker for neuronal tissue and Purkinje fiber cells. Immunoreactivity for protein gene product 9.5 along with other microscopic findings substantiates Purkinje fiber cell origin of the cardiac rhabdomyoma in the bearded seal and use of the termpurkinjeomato describe this lesion.

Neurological aspects of tuberous sclerosis in relation to MRI/MR spectroscopy findings in children with epilepsy

Our aim was to evaluate the relationship between the neurological outcome of tuberous sclerosis complex (TSC) and the findings obtained from both cranial magnetic resonance imaging (MRI) and single voxel proton spectroscopy (SVPS). MRIs of 13 children who met the diagnostic criteria for TSC were taken. Eleven of these children also underwent a prospective analysis of SVPS. Fisher's exact test and Mann-Whitney U test were used, where applicable, to detect any signs of the imaging data that would indicate poor outcome, or in other words, poor seizure control and/ or high degree of mental retardation. Poor seizure control was seen in eight of the patients and multiple seizure types in seven. Mental retardation was severe in six patients and mild/moderate in seven. MRI revealed multiple bilateral tubers and subependymal nodules (13/13), confluence of tubers (8/13), subcortical linear heterotopias (7/13), gyral cores (3/13) and cortical atrophy (3/13). SVPS findings of tubers were characterized by decreased NAA/Cr (1.43 +/- 0.33, p<0.001), increased Cho/Cr (0.91 +/- 0.082, p< 0.05) and mI/Cr (0.97 +/- 0.19, p<0.01) ratios when compared with those of the control group. Lactate peak was detected in six patients. Unfavorable outcome in TSC can be predicted with the help of the following: multiple seizure types, a number of confluent appearances of the tubers and cortical atrophy. SVPS could be a useful clue to understand the pathophysiologic function of the tubers, especially in children with refractory epilepsy along with TSC.

Cardiac fat-containing lesions are common in tuberous sclerosis complex

Tuberous sclerosis complex (TSC) is a highly variable, multisystem, genetic disorder that affects approximately 1:6,000 individuals. It has previously been thought that the cardiac manifestation of TSC is congenital rhabdomyomas, which occur during infancy and typically regress during childhood. Recently, there have been findings of cardiac fat-containing lesions in adult TSC patients that appear distinct from the presence of cardiac rhabdomyomas. We review the chest CT scans of 73 individuals with TSC to check for cardiac fat-containing lesions. Fat-containing lesions were found in the heart of approximately one-third of adolescents and adults with TSC. In this population with cardiac fat-containing lesions, no statistically significant difference was observed between the genders and between the different mutation types. Compared to those without cardiac fat findings, those with cardiac fat were more than twice as likely to have another abdominal manifestation of TSC. The results indicate that it may be appropriate to consider these cardiac fat foci as a clinical criterion for the diagnosis of TSC, given their frequency in our population. Our findings also suggest that a relation exists between the cardiac fat-containing lesions and other abdominal angiomyolipomas. More research regarding these cardiac fat-containing lesions is needed to better characterize their origin and clinical significance.

Syndromes predisposing to pediatric central nervous system tumors: lessons learned and new promises

Central nervous system (CNS) neoplasms are a leading cause of morbidity and mortality among children with cancer. In contrast to adults, a genetic basis for brain tumors is relatively common in children. A child harboring a germline mutation in a cancer-related gene will be predisposed to develop CNS tumors. These cancer predisposition syndromes are rare but pose overwhelming clinical and psychosocial challenges to families and the treating team. Recent significant advances in our understanding of the biological processes that govern these genetic conditions combined with international efforts to define and treat clinical aspects of these tumors are transforming the lives of these individuals. In this article, we summarize recent progress made for each of the major CNS tumor syndromes. We discuss the biological and clinical relevance of such advances, and suggest a comprehensive approach to a child affected by a predisposition to brain tumors.

Postnatal neurogenesis generates heterotopias, olfactory micronodules and cortical infiltration following single-cell Tsc1 deletion

Neurological symptoms in tuberous sclerosis complex (TSC) and associated brain lesions are thought to arise from abnormal embryonic neurogenesis due to inherited mutations in Tsc1 or Tsc2. Neurogenesis persists postnatally in the human subventricular zone (SVZ) where slow-growing tumors containing Tsc-mutant cells are generated in TSC patients. However, whether Tsc-mutant neurons from the postnatal SVZ contribute to brain lesions and abnormal circuit remodeling in forebrain structures remain unexplored. Here, we report the formation of olfactory lesions following conditional genetic Tsc1 deletion in the postnatal SVZ using transgenic mice or targeted single-cell electroporation. These lesions include migratory heterotopias and olfactory micronodules containing neurons with a hypertrophic dendritic tree. Most significantly, our data identify migrating glial and neuronal precursors that are re-routed and infiltrate forebrain structures (e.g. cortex) and become glia and neurons. These data show that Tsc1-mutant cells from the neonatal and juvenile SVZ generate brain lesions and structural abnormalities, which would not be visible using conventional non-invasive imaging. These findings also raise the hypothesis that micronodules and the persistent infiltration of cells to forebrain structures may contribute to network malfunction leading to progressive neuropsychiatric symptoms in TSC.

Single-cell Tsc1 knockout during corticogenesis generates tuber-like lesions and reduces seizure threshold in mice

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder characterized by mutations in Tsc1 or Tsc2 that lead to mammalian target of rapamycin (mTOR) hyperactivity. Patients with TSC suffer from intractable seizures resulting from cortical malformations known as tubers, but research into how these tubers form has been limited because of the lack of an animal model. To address this limitation, we used in utero electroporation to knock out Tsc1 in selected neuronal populations in mice heterozygous for a mutant Tsc1 allele that eliminates the Tsc1 gene product at a precise developmental time point. Knockout of Tsc1 in single cells led to increased mTOR activity and soma size in the affected neurons. The mice exhibited white matter heterotopic nodules and discrete cortical tuber-like lesions containing cytomegalic and multinucleated neurons with abnormal dendritic trees resembling giant cells. Cortical tubers in the mutant mice did not exhibit signs of gliosis. Furthermore, phospho-S6 immunoreactivity was not upregulated in Tsc1-null astrocytes despite a lower seizure threshold. Collectively, these data suggest that a double-hit strategy to eliminate Tsc1 in discrete neuronal populations generates TSC-associated cortical lesions, providing a model to uncover the mechanisms of lesion formation and cortical hyperexcitability. In addition, the absence of glial reactivity argues against a contribution of astrocytes to lesion-associated hyperexcitability.

Seizures and intellectual outcome: clinico-radiological study of 30 Egyptian cases of tuberous sclerosis complex

BACKGROUND AND OBJECTIVES

Tuberous sclerosis complex (TSC) is a multi-systemic disorder that involves primarily CNS, skin, kidney and heart. The aim of this study is to determine whether seizures type, interictal EEGs and tubers burden in MRI are correlated to seizure and intellectual outcome, and to identify the clinical risk factors for mental retardation and developing autism in these patients.

METHODS

This was a prospective study that was conducted on 30 Egyptian children with tuberous sclerosis complex (TSC), diagnosed according to the criteria of National Institutes of Health consensus conference revised the diagnostic criteria for TSC. All patients underwent clinical and psychometric evaluation, interictal EEG, and MRI brain.

RESULTS AND CONCLUSIONS

We found that poor intellectual outcome is related to early onset of seizures, infantile spasms, severely epileptogenic EEG findings and tuber burden on the Left side. Autistic behavior is related to seizure type (more with infantile spasms), severely epileptogenic EEG findings, frontal location of tubers and higher number of tubers (>8).

Evidence for population variation in TSC1 and TSC2 gene expression

BACKGROUND

Tuberous sclerosis complex (TSC) is an autosomal dominant neurogenetic disorder caused by mutations in one of two genes, TSC1 or TSC2, which encode the proteins hamartin and tuberin, respectively 123. Common features of TSC include intractable epilepsy, mental retardation, and autistic features. TSC is associated with specific brain lesions, including cortical tubers, subependymal nodules and subependymal giant cell astrocytomas. In addition, this disease frequently produces characteristic tumors, termed hamartomas, in the kidneys, heart, skin, retina, and lungs. Disease severity in TSC can be quite variable and is not determined by the primary mutation alone. In fact, there is often considerable variability in phenotype within single families, where all affected individuals carry the same mutation. Factors suspected to influence phenotype in TSC include the specific primary mutation, random occurrence of second-hit somatic mutations, mosaicism, "modifying genes", and environmental factors. In addition to these factors, we hypothesize that differences in mRNA expression from the non-mutated TSC allele, or possibly from the mutated allele, play a part in modifying disease severity. Common genetic variants that regulate mRNA expression have previously been shown to play important roles in human phenotypic variability, including disease susceptibility. A prediction based on this idea is that common regulatory variants that influence disease severity in TSC should be detectable in non-affected individuals.

METHODS

A PCR/primer extension assay was used to measure allele specific expression of TSC1 and TSC2 mRNAs in leukocytes isolated from normal volunteers. This assay can be used to measure "allelic expression imbalance" (AEI) in individuals by making use of heterozygous "marker" single nucleotide polymorphisms (SNPs) located within their mRNA.

RESULTS

In this study we show for the first time that TSC1 and TSC2 genes exhibit allele-specific differences in mRNA expression in blood leukocytes isolated from normal individuals.

CONCLUSIONS

These results support the possibility that allele-specific variation in TSC mRNA expression contributes to the variable severity of symptoms in TSC patients.

[Characteristics of tuberous sclerosis in children]

Tuberous sclerosis complex is a genetic multisystem disease characterized by hamartic development of many organs, most notably the brain, heart, kidneys, lungs, and skin. This autosomic dominant disorder results from mutations in one of two genes, TSC1 and TSC2, coding for hamartin and tuberin, respectively. The hamartin-tuberin complex inhibits the mammalian target of rapamycin pathway, which controls cell growth and proliferation. The clinical presentation is highly variable and most features of tuberous sclerosis become evident only in childhood after the child is several years of age, limiting their usefulness for early diagnosis. The aim of this article is to define the pediatric clinical manifestations of tuberous sclerosis in correlation with patient age. Sometimes, a prenatal diagnosis can be made based on fetal ultrasound and MRI, which show cardiac and brain lesions. However, newborns are most often asymptomatic. In the 1st year, seizures are the most common symptoms, with a high incidence of infantile spasms. In children between 2 and 10 years of age, neurological symptoms are the most frequent with epilepsy, mental retardation, and autism, but extraneurological manifestations can be diagnosed. In adolescents, most features of tuberous sclerosis become evident and renal and pulmonary manifestations must be sought. The knowledge of age-dependent clinical features of tuberous sclerosis can provide an earlier diagnosis and improve the management of these patients with a special role for multidisciplinary consultation.

Arterial aneurysms and tuberous sclerosis: a classic but little known association

Tuberous sclerosis is a rare autosomal dominant syndrome in which aortic aneurysm is a classic but little known cause of sudden death. We report a 20-month-old boy with tuberous sclerosis and iliofemoral arterial aneurysms. This case highlights the importance of systematic screening for such vascular complications. Multislice CT or MRI is mandatory as a screening and diagnostic tool in this setting to complement US with Doppler examination.

Long-term outcome of transcatheter embolization of renal angiomyolipomas due to tuberous sclerosis complex

PURPOSE

Complications from renal angiomyolipomas (AMLs) are common in patients with tuberous sclerosis complex (TSC) and tumors greater than 4 cm are more likely to cause symptoms. AMLs are the most common cause of death in adults with TSC. We present our long-term experience with transcatheter tumor embolization as a definitive treatment for AMLs due to TSC.

MATERIALS AND METHODS

A total of 16 patients with TSC between 7.5 and 47.2 years old with symptomatic or large (4 to 21 cm) AMLs underwent embolization. Followup consisted of periodic physician visits or telephone contacts and renal imaging.

RESULTS

The 16 patients underwent 18 treatment sessions to embolize 27 tumors. There were no intraoperative complications. The post-embolization syndrome occurred in 11 individuals but all responded to medical management. Two individuals had an arterial aneurysm within a tumor. The AML size decreased in the 13 patients who were imaged 3 months after treatment, and the 7 patients who were imaged 3 to 9 years after treatment have shown no tumor regrowth. No renal failure or hemorrhage has developed in patients following embolization.

CONCLUSIONS

Transcatheter embolization of symptomatic or large AMLs due to TSC prevents hemorrhage and renal loss. The treatment is minimally invasive, preserves renal function, and can be performed multiple times. All of the patients who underwent followup renal imaging after embolization showed decreased AML size, and none of the 16 patients has developed renal loss or renal insufficiency in these individuals. Embolization should be considered the initial treatment of choice for large or symptomatic AMLs.

Proton spectroscopic findings in children with epilepsy owing to tuberous sclerosis complex

Tuberous sclerosis complex is an autosomal dominant disorder that often causes refractory seizures. The presence of multiple lesions makes it difficult to identify a single lesion responsible for the epilepsy. Our purpose is to assess the single-voxel proton spectroscopic findings of the tubers in 11 children with tuberous sclerosis complex. Prior to age 4 years, all of the patients had presented with epileptic seizures and multiple bilateral tubers in magnetic resonance images. Single-voxel proton spectroscopy was performed from the tubers especially showing epileptogenic activity using both the long and short echo time and in 14 controls. The results were analyzed using the Mann-Whitney U-test. Compared with the control group, the spectroscopic findings of tubers were characterized by decreased N-acetylaspartate to creatine ratios (1.43 +/- 0.33; P < .001) in both the long and short echo time spectra, increased choline to creatine ratios (0.91 +/- 0.082; P < .05), and myo-inositol to creatine ratios (0.97 +/- 0.19; P < .01) in the short echo time spectra. A lactate peak was detected in the regions corresponding to an epileptic focus on electroencephalography in six patients. Single-voxel proton spectroscopy could be a useful noninvasive method to evaluate epileptogenic tubers.

Genetic insights into familial tumors of the nervous system

Nervous system tumors represent unique neoplasms that arise within the central and peripheral nervous system. While the vast majority of nervous system neoplasm occur sporadically, most of the adult and pediatric forms have a hereditary equivalent. In a little over a decade, we have seen a tremendous increase in knowledge of the primary genetic basis of many of the familial cancer syndromes that involve the nervous system, syndromes that are mostly inherited as autosomal dominant traits. In this review, we discuss the most recent findings on the genetic basis of hereditary nervous system tumors. The identification of genes associated with familial cancer syndromes has in some families enabled a "molecular diagnosis" that complements clinical assessment and allows directed cancer surveillance for those individuals determined to be at-risk for disease.

Diagnosis of tuberous sclerosis complex

Tuberous sclerosis complex is a dominantly inherited disorder affecting multiple organs; because of its phenotypic variability, the diagnosis of tuberous sclerosis complex can be difficult in the young or in individuals with subtle findings. Recently revised consensus diagnostic criteria for tuberous sclerosis complex reflect an improved understanding of its clinical manifestations and its genetic and molecular mechanisms. The diagnostic criteria are based on the premise that there are probably no truly pathognomonic clinical signs for tuberous sclerosis complex; signs that were once regarded as specific occur as isolated findings in individuals with no other clinical or genetic evidence of tuberous sclerosis complex. Consequently, the revised criteria require tuberous sclerosis complex-associated lesions of two or more organ systems or at least two dissimilar lesions of the same organ to confirm the diagnosis. The addition of DNA testing complements clinical diagnosis and allows more precise genetic counseling and, in some individuals, prenatal diagnosis. Nevertheless, the 15% false-negative rate for DNA testing and the occurrence of germline mosaicism in about 2% of individuals with tuberous sclerosis complex make it difficult to exclude the diagnosis of tuberous sclerosis complex in family members.

Renal and adrenal tumors in children

Survival rates for children with kidney tumors approach 90% for even the most advanced stages of disease, but the surgical management of large lesions remains challenging. With the development of additional chemotherapeutic regimens and the use of radiation therapy, survival rates have improved dramatically. The National Wilms' Tumor Study has conducted four long-term studies addressing how adjunctive therapy may be tailored optimally to maximize survival and minimize the exposure to chemotherapy and radiation therapy.

Tuberous sclerosis complex in a young woman diagnosed incidentally on the basis of pregnancy ultrasonography

Tuberous sclerosis complex (TSC) is more prevalent than previously believed and most cases result from new mutations and, hence, do not have affected relatives. Many patients who meet the new diagnostic criteria have unrecognized skin lesions and/or occult lesions in internal organs. As early diagnosis and appropriate intervention can reduce morbidity and mortality from the neurologic. renal, and pulmonary complications of TSC, physicians should be alert for the dermatological signs of the condition and for the incidental finding of TSC lesions during diagnostic testing. Patients with TSC may be asymptomatic and of normal intelligence. We report a case of TSC diagnosed by the incidental finding of renal lesions in a young woman during pregnancy ultrasonic examination.

Hereditary kidney cancer

Significant advances have been made in the understanding of the genetic basis of familial renal neoplasia. Identification of key genes in the pathogenesis of various hereditary renal cancer syndromes has provided opportunities to screen family members at risk and to explore the significance of these genetic abnormalities in the development and genesis of much more common sporadic counterparts. As researchers continue to delineate critical carcinogenic pathways and accumulate expansive knowledge on oncogenic mechanisms driving cancer initiation and progression at the cellular and molecular levels, this information will be integrated and translated into effective diagnostic and therapeutic strategies that will dictate clinical management of all renal cancers.

Tuberous sclerosis: a presentation of less-commonly encountered stigmata

The protean manifestations of the tuberous sclerosis complex have lent this condition to extensive review in textbooks and in the medical literature. This condition generally presents by virtue of its neurological manifestations. Osseous stigmata, when encountered, are generally asymptomatic and do not require specific treatment owing to their benignity. We present the case of a young man with a slowly enlarging facial swelling for whom cosmetic surgery was considered. The swelling, present since childhood, had in time assumed disfiguring proportions. In what was hitherto considered an isolated facial deformity, a skull radiograph followed by CT revealed neurological stigmata of tuberous sclerosis. A large cerebellar hamartoma, proliferative soft tissue in the scalp adjacent to focal hyperostosis of the calvarium and the accompanying hemifacial changes seen in this patient constitute less commonly described features of tuberous sclerosis.

Genetic insights into familial cancers-- update and recent discoveries

While the vast majority of cancers are believed to occur sporadically, most forms of cancer, both adult and paediatric, have a hereditary equivalent. In the case of adult malignancies, these include hereditary breast and ovarian cancer and syndromes such as the multiple endocrine neoplasias types 1 and 2 characterised by specific tumours of the endocrine gland system. In the case of paediatric malignancies, these include syndromes such as retinoblastoma and Wilms tumour. In a little over a single decade, we have seen a tremendous increase in the knowledge of the primary genetic basis of many of the familial cancer syndromes. The majority of familial syndromes are inherited as autosomal dominant traits including hereditary colon cancer and familial malignant melanoma, however, the genetics behind autosomal recessive disorders such as Bloom syndrome and Fanconi anaemia are also being elucidated. A third mode of inheritance less well understood in the setting of familial cancer is that of imprinting recently observed in a subset of families with inherited paraganglioma. In this review, we discuss 31 genes inherited in an autosomal dominant manner associated with 20 familial cancer syndromes. Genes inherited in an autosomal recessive manner linked to familial cancer syndromes are also discussed. The identification of genes associated with familial cancer syndromes has in some families enabled a 'molecular diagnosis' that complements clinical assessment and allows directed cancer surveillance for those individuals determined to be at-risk of disease.

Use of CO2 laser in the treatment of periungual fibromas associated with tuberous sclerosis

BACKGROUND

Tuberous sclerosis complex is an autosomal dominant disorder with variable clinical expression. In severe forms it may involve almost any organ system. Periungual fibromas are a common cutaneous manifestation and a frequent source of cosmetic and functional concern. Current treatment involves surgical excision of the lesions.

OBJECTIVE

To evaluate laser vaporization of periungual fibromas and to compare results to the standard surgical treatment.

METHODS

A patient with tuberous sclerosis and recurrent periungual fibromas was treated with a continuous wave CO2 laser in sequential focused and defocused modes at 10-15 W.

RESULTS

Laser treatment required approximately 10 seconds per lesion and produced no intraoperative bleeding. The wounds healed well with good cosmetic results.

CONCLUSION

Though similar to conventional surgery in terms of cosmetic satisfaction, CO2 laser presents a viable alternative to surgery through significantly reduced treatment time and amount of bleeding.

Neurologic manifestations of tuberous sclerosis complex

Tuberous sclerosis complex (TSC) is a multiorgan disorder that primarily affects the brain, skin, and kidneys. Recent advances have elucidated the genetics of this complex, which has helped lead to an increased understanding of the basic neurobiology of this disorder. There is both phenotypic and geneotypic heterogeneity. The treatment of epilepsy remains a major challenge in these patients, and there is an increasing role for epileptic surgery. Many patients with TSC continue to have intractable seizures. Early identification to ensure proper monitoring and genetic counseling continue to be important clinically. The neurologist must be aware of other organ involvement, particularly the kidneys, and the lungs in female patients, to ensure appropriate monitoring for complications. It is also important to be aware of the marked variability of expression in all the clinical features of TSC.

Insulinoma in a patient with tuberous sclerosis: is there an association?

OBJECTIVE

To describe a patient with tuberous sclerosis who, on initial assessment, had neurologic symptoms, which were ultimately found to be caused by an insulinoma.

METHODS

We present a case report with clinical, laboratory, and radiologic data. The literature is reviewed relative to tuberous sclerosis and islet cell tumors, and a possible association is discussed.

RESULTS

A 43-year-old man with a history of tuberous sclerosis required medical attention because of mental confusion and slurred speech and was found to have hypoglycemia. Neuroradiologic imaging showed no new lesions to account for his symptoms. His physical examination was striking for a large abdominal mass, which showed increased uptake on octreotide scanning. After surgical resection, the mass measured 21 cm and was found to be an insulinoma. Blood glucose values were normal postoperatively and on follow-up, and the patient had no recurrence of the symptoms.

CONCLUSION

From this report, we emphasize two findings. First, we draw clinicians' attention to the possibility of an association between islet cell tumors and tuberous sclerosis and suggest consideration of this diagnosis in patients with tuberous sclerosis who have new or worsening neurologic symptoms. Second, the insulinoma we describe is, to our knowledge, the largest to be reported thus far in the literature.

Aortic aneurysms in children and young adults with tuberous sclerosis: report of two cases and review of the literature

Abdominal aortic aneurysms (AAAs) in children and young adults are rare; some have been observed in patients with tuberous sclerosis (TS). We report two cases and review the literature. A 9-year-old girl with TS was diagnosed with a 3-cm calcified AAA, and a 41-year-old man with TS was diagnosed with a 7.5-cm thoracic aortic aneurysm (TAA). Both patients underwent open repair with a tube polyester graft without complication. They are both doing well at 7 and 8 years after surgery. Pathologic evaluation revealed medial atrophy and focal medial disruption in the aortic wall in both patients. With our two cases, 15 patients with TS and aneurysms have been reported; 12 had AAA, and four had TAA (one patient had both). Three AAAs and two TAAs ruptured. Six patients died because of aneurysmal disease. There is an association between TS and aortic aneurysms. Patients should be screened for aortic aneurysms at the time TS is diagnosed and annually thereafter. Because of the high risk of rupture, early elective repair is suggested. New aortic aneurysms after repair may also develop.

Hamartin expression and interaction with tuberin in tumor cell lines and primary cultures

Tuberous sclerosis (TSC) is a neurocutaneous disorder characterized by multi-system hamartomatous lesions, and results from a mutation in TSC1, that encodes hamartin, or TSC2, that encodes tuberin. We have examined hamartin expression in a diverse range of human and rat cell lines and primary cultured cells derived from tissues that express hamartin in vivo. Strong hamartin signal was detected in every cell line of human origin examined, representing neuronal, epithelial, lymphoid, renal, vascular smooth muscle, liver, and prostatic cells. Primary cell cultures of oligodendroglioma, meningioma, and glioblastoma multiforme origin were also found to express hamartin. Hamartin was also detected in the rat PC12 cell line, as well as purified primary cultures of rat cortical neurons, astrocytes, and oligodendroglia, with a stronger signal found in astrocytes. Using co-immunoprecipitation, we have also confirmed the physical interaction of tuberin and hamartin in a diverse range of human and rat cell types. These findings demonstrate that hamartin is widely expressed in human and rat cell lines and cultures, and demonstrate that hamartin expression is not lost during the establishment of tumor cell lines or primary cultures. This suggests that the cell lines and cultures studied may serve as useful in vitro models for biochemical investigations involving hamartin and tuberin both individually and as a complex, as well as studies to elucidate the mechanisms underlying the organ-specific pathology of TSC.

Abnormal sudomotor function in the hypomelanotic macules of tuberous sclerosis complex

To investigate the integrity of sympathetic innervation in the hypomelanotic macules of tuberous sclerosis complex, we studied sudomotor function in nine patients with tuberous sclerosis complex. Postganglionic sudomotor function was assessed using the Silastic imprint test in nine patients with tuberous sclerosis complex who have at least one hypomelanotic macule greater than 2 cm in diameter. Sweating was induced by iontophoresis with 0.5% pilocarpine nitrate and sweat droplets were counted under a microscope using a 1 x 1 cm grid. Silastic imprint testing of an analogous skin area contralateral to the hypomelanotic macule was measured as a control. Sweat volume quantitation using sweat collectors was performed in five of the subjects. The sweat volume collected from the hypomelanotic macule was reduced compared to the control skin in four of the five subjects. Sweat droplet counts from the hypomelanotic macule were significantly reduced in only one of nine subjects. These data suggest that, although there is no difference in the number of functioning sweat glands in most hypomelanotic macules, the sweat glands produce less sweat (ie, decreased sweat volume) than in normal skin. We hypothesize that focal abnormalities of sympathetic innervation might be responsible for the hypomelanotic macules of tuberous sclerosis complex.

Tuberous sclerosis complex

Tuberous sclerosis complex is an autosomal dominant disorder that causes significant complications in multiple organ systems. Both basic science and clinical research on tuberous sclerosis complex have flourished in recent years, improving our understanding of its molecular genetics and pathophysiology. Two tuberous sclerosis complex genes cause nearly identical phenotypes, and great progress has been made towards understanding how each of these genes functions. The recognition of tuberous sclerosis complex improved with revised diagnostic criteria, and the management of many of the complications of tuberous sclerosis complex has improved.

Tuberous Sclerosis Consensus Conference: recommendations for diagnostic evaluation. National Tuberous Sclerosis Association

At the recent Tuberous Sclerosis Consensus Conference, a subcommittee proposed recommendations to guide the rational use of diagnostic studies in patients with tuberous sclerosis complex. Recommendations were made for diagnostic evaluation at the time of diagnosis, when testing helps both to establish the diagnosis and to identify potential complications. Additional guidelines were proposed for the ongoing surveillance of established patients to detect later complications of tuberous sclerosis complex. In the absence of comprehensive population studies to govern the use of diagnostic studies in individuals with tuberous sclerosis complex, the panel developed guidelines based on the disorder's natural history, concentrating on complications that are common, clinically significant, and more easily managed when found early. Finally, the group made suggestions for the use of diagnostic tests to identify family members who have tuberous sclerosis complex. Although these recommendations should standardize and improve our use of diagnostic studies in individuals with tuberous sclerosis complex, the clinical approach in a given patient must remain flexible enough to meet the needs of individual patients and families.