201
|
|
202
|
Mühler MR, Rake A, Schwabe M, Schmidt S, Kivelitz D, Chaoui R, Hamm B. Value of fetal cerebral MRI in sonographically proven cardiac rhabdomyoma. Pediatr Radiol 2007; 37:467-74. [PMID: 17357805 DOI: 10.1007/s00247-007-0436-y] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2007] [Revised: 02/16/2007] [Accepted: 02/18/2007] [Indexed: 11/26/2022]
Abstract
BACKGROUND Tuberous sclerosis complex (TSC) is an autosomal dominant phakomatosis associated with intracardiac rhabdomyomas. OBJECTIVE The aim of our study was to examine the value of cerebral MRI in diagnosing TSC in fetuses with intracardiac rhabdomyomas, applying the TSC Consensus Conference (TSCCC) criteria. MATERIALS AND METHODS In a prospective manner six consecutive fetuses with cardiac rhabdomyomas (21-34 weeks' gestation) underwent cerebral MRI. The MRI results were correlated with clinical follow-up at 10-34 months after birth, histology, and genetic data. RESULTS In five of the six fetuses the diagnosis of TSC was established. In two of five fetuses MRI demonstrated cerebral manifestations of TSC that correlated well with severe epilepsy manifesting during the follow-up period. In another two of five fetuses MRI as well as clinical follow-up were normal. One of five pregnancies was terminated and histology demonstrated microscopically small subependymal nodules not demonstrated by MRI. CONCLUSION The results of our study agree with the available literature that fetal MRI is sufficient for the detection of cerebral lesions in TSC and should be better promoted. The TSCCC criteria can also be applied to fetal MRI.
Collapse
Affiliation(s)
- Matthias R Mühler
- Department of Radiology, Charité Universitätsmedizin Berlin, Campus Mitte, Charitéplatz 1, 10117, Berlin, Germany.
| | | | | | | | | | | | | |
Collapse
|
203
|
D'Armiento J, Imai K, Schiltz J, Kolesnekova N, Sternberg D, Benson K, Pardo A, Selman M, Smolarek T, Vundavalli M, Sonnet J, Szabolcs M, Chada K. Identification of the benign mesenchymal tumor gene HMGA2 in lymphangiomyomatosis. Cancer Res 2007; 67:1902-9. [PMID: 17332316 DOI: 10.1158/0008-5472.can-06-1122] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The normal expression pattern of HMGA2, an architectural transcription factor, is primarily restricted to cells of the developing mesenchyme before their overt differentiation during organogenesis. A detailed in situ hybridization analysis showed that the undifferentiated mesoderm of the embryonic lung expressed Hmga2 but it was not expressed in the newborn or adult lung. Previously, HMGA2 was shown to be misexpressed in a number of benign, differentiated mesenchymal tumors including lipomas, uterine leiomyomas, and pulmonary chondroid hamartomas. Here, we show that HMGA2 is misexpressed in pulmonary lymphangiomyomatosis (LAM), a severe disorder of unknown etiology consisting of lymphatic smooth muscle cell proliferation that results in the obstruction of airways, lymphatics, and vessels. Immunohistochemistry was done with antibodies to HMGA2 and revealed expression in lung tissue samples obtained from 21 patients with LAM. In contrast, HMGA2 was not expressed in sections of normal adult lung or other proliferative interstitial lung diseases, indicating that the expression of HMGA2 in LAM represents aberrant gene activation and is not due solely to an increase in cellular proliferation. In vivo studies in transgenic mice show that misexpression of HMGA2 in smooth muscle cells resulted in increased proliferation of these cells in the lung surrounding the epithelial cells. Therefore, similar to the other mesenchymal neoplasms, HMGA2 misexpression in the smooth muscle cell leads to abnormal proliferation and LAM tumorigenesis. These results suggest that HMGA2 plays a central role in the pathogenesis of LAM and is a potential candidate as a therapeutic target.
Collapse
Affiliation(s)
- Jeanine D'Armiento
- Department of Medicine, Surgery, and Pathology, College of Physicians and Surgeons, Columbia University, 630 West 168th Street, New York, NY, USA.
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
204
|
Abstract
Tuberous sclerosis complex (TSC) is a congenital syndrome characterized by the widespread development of benign tumors in multiple organs, caused by mutations in one of the tumor suppressor genes, TSC1 or TSC2. About 80% of affected patients have a new mutation, and the remaining 20% have inherited a TSC gene mutation from a parent. The disorder affects approximately 1 in 6000 individuals. Cortical tubers are the neuropathological hallmark of TSC. The most common neurological manifestations of TSC are epilepsy, mental retardation, and autistic behavior. Epilepsy occurs in up to 80-90% of patients and is often intractable, with a poor response to anticonvulsant medications. While the molecular basis of TSC is well established, far less is known about the mechanisms of epilepsy in this disorder. In this article, we first summarize known clinical aspects of TSC with emphasis on its neurological features. Then, based on the molecular, pathological, immunohistochemical, neurochemical, and physiological properties of tubers in patients with TSC and in animal models, we discuss possible mechanisms of seizures and epileptogenesis in TSC. Finally, we provide an updated literature review and a consensus statement from the Tuberous Sclerosis Complex Working Group for future research into the mechanisms of epilepsy in TSC.
Collapse
Affiliation(s)
- Gregory L Holmes
- Neuroscience Center at Dartmouth, Section of Neurology, Dartmouth Medical School, Hanover, New Hampshire, USA.
| | | |
Collapse
|
205
|
Abstract
Tuberous sclerosis complex (TSC) is an autosomal dominant disorder caused by mutations of either of the two tumor suppressor genes, TSC1 and TSC2, encoding hamartin and tuberin, respectively. TSC is pathologically characterized by the occurrence of multiple hamartias (focal dysplasias) and hamartomas (benign tumors) in the brain and many other organs. Cortical tubers are hamartias in the cerebral cortex responsible for many neuropsychiatric symptoms of TSC. Unlike TSC-associated hamartomas, cortical tubers do not result from second somatic mutations of the TSC gene, and the mechanism by which they occur remains obscure. Histologically, the most conspicuous feature of cortical tubers is the presence of abnormal giant cells, which show abnormal size and differentiation. Recent studies on human TSC and its animal models have elucidated the critical roles of hamartin and tuberin regulating the growth and differentiation of neural cells.
Collapse
Affiliation(s)
- Masashi Mizuguchi
- Department of Pediatrics, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
| |
Collapse
|
206
|
Devlin LA, Shepherd CH, Crawford H, Morrison PJ. Tuberous sclerosis complex: clinical features, diagnosis, and prevalence within Northern Ireland. Dev Med Child Neurol 2007. [PMID: 16700943 DOI: 10.1111/j.1469-8749.2006.tb01302.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Lisa A Devlin
- Immunology Day Centre, Royal Victoria Hospital, Belfast, UK.
| | | | | | | |
Collapse
|
207
|
Kozlowski P, Roberts P, Dabora S, Franz D, Bissler J, Northrup H, Au KS, Lazarus R, Domanska-Pakiela D, Kotulska K, Jozwiak S, Kwiatkowski DJ. Identification of 54 large deletions/duplications in TSC1 and TSC2 using MLPA, and genotype-phenotype correlations. Hum Genet 2007; 121:389-400. [PMID: 17287951 DOI: 10.1007/s00439-006-0308-9] [Citation(s) in RCA: 126] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2006] [Accepted: 11/23/2006] [Indexed: 10/23/2022]
Abstract
Tuberous sclerosis (TSC) is an autosomal dominant disorder caused by mutations in either of two genes, TSC1 and TSC2. Point mutations and small indels account for most TSC1 and TSC2 mutations. We examined 261 TSC DNA samples (209 small-mutation-negative and 52 unscreened) for large deletion/duplication mutations using multiplex ligation-dependent probe amplification (MLPA) probe sets designed to permit interrogation of all TSC1/2 exons, as well as 15-50 kb of flanking sequence. Large deletion/duplication mutations in TSC1 and TSC2 were identified in 54 patients, of which 50 were in TSC2, and 4 were in TSC1. All but two mutations were deletions. Only 13 deletions were intragenic in TSC2, and one in TSC1, so that 39 (73%) deletions extended beyond the 5', 3' or both ends of TSC1 or TSC2. Mutations were identified in 24% of small-mutation-negative and 8% of unscreened samples. Eight of 54 (15%) mutations were mosaic, affecting 34-62% of cells. All intragenic mutations were confirmed by LR-PCR. Genotype/phenotype analysis showed that all (21 of 21) patients with TSC2 deletions extending 3' into the PKD1 gene had kidney cysts. Breakpoints of intragenic deletions were randomly distributed along the TSC2 sequence, and did not preferentially involve repeat sequence elements. Our own 20-plex probe sets gave more robust performance than the 40-plex probe sets from MRC-Holland. We conclude that large deletions in TSC1 and TSC2 account for about 0.5 and 6% of mutations seen in TSC patients, respectively, and MLPA is a highly sensitive and accurate detection method, including for mosaicism.
Collapse
Affiliation(s)
- Piotr Kozlowski
- Genetics Laboratory, Division of Translational Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
208
|
Au KS, Williams AT, Roach ES, Batchelor L, Sparagana SP, Delgado MR, Wheless JW, Baumgartner JE, Roa BB, Wilson CM, Smith-Knuppel TK, Cheung MYC, Whittemore VH, King TM, Northrup H. Genotype/phenotype correlation in 325 individuals referred for a diagnosis of tuberous sclerosis complex in the United States. Genet Med 2007; 9:88-100. [PMID: 17304050 DOI: 10.1097/gim.0b013e31803068c7] [Citation(s) in RCA: 257] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Tuberous sclerosis complex is an autosomal dominant neurocutaneous disorder marked by hamartoma growth in multiple organ systems. We performed mutational analyses on 325 individuals with definite tuberous sclerosis complex diagnostic status. We identified mutations in 72% (199/257) of de novo and 77% (53/68) of familial cases, with 17% of mutations in the TSC1 gene and 50% in the TSC2 gene. There were 4% unclassified variants and 29% with no mutation identified. Genotype/phenotype analyses of all observed tuberous sclerosis complex findings in probands were performed, including several clinical features not analyzed in two previous large studies. We showed that patients with TSC2 mutations have significantly more hypomelanotic macules and learning disability in contrast to those with TSC1 mutations, findings not noted in previous studies. We also observed results consistent with two similar studies suggesting that individuals with mutations in TSC2 have more severe symptoms. On performing meta-analyses of our data and the other two largest studies in the literature, we found significant correlations for several features that individual studies did not have sufficient power to conclude. Male patients showed more frequent neurologic and eye symptoms, renal cysts, and ungual fibromas. Correlating genotypes with phenotypes should facilitate the disease management of tuberous sclerosis complex.
Collapse
Affiliation(s)
- Kit Sing Au
- Department of Pediatrics, The University of Texas Medical School at Houston, 77030, USA.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
209
|
|
210
|
Jeong IC, Kim JT, Hwang YS, Kim JA, Lee JS. Renal manifestations in tuberous sclerosis complex. KOREAN JOURNAL OF PEDIATRICS 2007. [DOI: 10.3345/kjp.2007.50.2.178] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Il Cheon Jeong
- Department of Pediatrics, The Institute of Kidney Disease, Yonsei University College of Medicine Seoul, Korea
| | - Ji Tae Kim
- Department of Pediatrics, The Institute of Kidney Disease, Yonsei University College of Medicine Seoul, Korea
| | - You Sik Hwang
- Department of Pediatrics, The Institute of Kidney Disease, Yonsei University College of Medicine Seoul, Korea
| | - Jung A Kim
- Department of Pediatrics, The Institute of Kidney Disease, Yonsei University College of Medicine Seoul, Korea
| | - Jae Seung Lee
- Department of Pediatrics, The Institute of Kidney Disease, Yonsei University College of Medicine Seoul, Korea
| |
Collapse
|
211
|
Juvet SC, McCormack FX, Kwiatkowski DJ, Downey GP. Molecular pathogenesis of lymphangioleiomyomatosis: lessons learned from orphans. Am J Respir Cell Mol Biol 2006; 36:398-408. [PMID: 17099139 PMCID: PMC2176113 DOI: 10.1165/rcmb.2006-0372tr] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Lymphangioleiomyomatosis (LAM) is a rare progressive cystic lung disease affecting young women. The pivotal observation that LAM occurs both spontaneously and as part of the tuberous sclerosis complex (TSC) led to the hypothesis that these disorders share common genetic and pathogenetic mechanisms. In this review we describe the evolution of our understanding of the molecular and cellular basis of LAM and TSC, beginning with the discovery of the TSC1 and TSC2 genes and the demonstration of their involvement in sporadic (non-TSC) LAM. This was followed by rapid delineation of the signaling pathways in Drosophila melanogaster with confirmation in mice and humans. This knowledge served as the foundation for novel therapeutic approaches that are currently being used in human clinical trials.
Collapse
Affiliation(s)
- Stephen C Juvet
- National Jewish Medical and Research Center, 1400 Jackson Street, Denver, CO 80206, USA
| | | | | | | |
Collapse
|
212
|
Jansen AC, Sancak O, D'Agostino MD, Badhwar A, Roberts P, Gobbi G, Wilkinson R, Melanson D, Tampieri D, Koenekoop R, Gans M, Maat-Kievit A, Goedbloed M, van den Ouweland AMW, Nellist M, Pandolfo M, McQueen M, Sims K, Thiele EA, Dubeau F, Andermann F, Kwiatkowski DJ, Halley DJJ, Andermann E. Unusually mild tuberous sclerosis phenotype is associated with TSC2 R905Q mutation. Ann Neurol 2006; 60:528-539. [PMID: 17120248 DOI: 10.1002/ana.21037] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
OBJECTIVE To report the clinical manifestations and functional aspects of Tuberous Sclerosis Complex (TSC), resulting from Codon 905 mutations in TSC2 gene. METHODS We performed a detailed study of the TSC phenotype and genotype in a large French-Canadian kindred (Family A). Subsequently, clinical and molecular data on 18 additional TSC families with missense mutations at the same codon of TSC2 were collected. Functional studies were performed on the different missense changes and related to the phenotype. RESULTS A 2714G>A (R905Q) mutation was identified in Family A. The TSC phenotype in this family was unusually mild and characterized by hypomelanotic macules or focal seizures that remitted spontaneously or were easily controlled with medication. Diagnostic criteria were met in only a minority of mutation carriers. Other families with the R905Q mutation were found to have a similar mild phenotype. In contrast, patients with a 2713C>T (R905W) or a 2713C>G (R905G) mutation had more severe phenotypes. Although all three amino acid substitutions were pathogenic, the R905W and R905G substitutions affected tuberin function more severely than R905Q. INTERPRETATION Codon 905 missense mutations in TSC2 are relatively common. The TSC2 R905Q mutation is associated with unusually mild disease, consistent with functional studies. Combined with previous reports, it is apparent that certain TSC2 missense mutations are associated with a mild form of tuberous sclerosis, which in many patients does not meet standard diagnostic criteria. These findings have implications for the large number of patients with limited clinical features of TSC and for genetic counseling in these families.
Collapse
Affiliation(s)
- An C Jansen
- Neurogenetics Unit, Montreal Neurological Hospital and Institute, McGill University, Montreal, Quebec, Canada
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
213
|
Rakowski SK, Winterkorn EB, Paul E, Steele DJR, Halpern EF, Thiele EA. Renal manifestations of tuberous sclerosis complex: Incidence, prognosis, and predictive factors. Kidney Int 2006; 70:1777-82. [PMID: 17003820 DOI: 10.1038/sj.ki.5001853] [Citation(s) in RCA: 333] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Tuberous sclerosis complex is a genetic disorder characterized by hamartomatous lesions in multiple organs, frequently involving the kidney. We conducted a retrospective review of the clinical and radiographic records of 167 patients with tuberous sclerosis to determine the frequency of renal disease, the likelihood of significant renal morbidity, and the effects of genotype (TSC1 vs TSC2) and gender on renal phenotype. Renal lesions were seen in 57.5% of patients. Of these, angiomyolipoma (AML) occurred in 85.4%, cysts in 44.8%, and renal cell carcinoma in 4.2%. Both AML and cysts were significantly more common and more numerous in TSC2 than in TSC1. AML was significantly more common in female than in male patients, but cysts showed no correlation with gender. Eleven patients developed renal abnormalities during their care in this practice at an average age of onset of 11.3 years (range 3.8-23 years). The frequency and number of renal lesions were positively correlated with age. Interventions, including arterial embolization and nephrectomy, were performed in 11 (6.6%) patients. Among female patients with lymphangioleiomyomatosis, renal AML was universally present. Our findings confirm a high rate of renal involvement; a low rate of serious complications; significant associations between renal involvement, genotype, and gender; and a significant association between renal and pulmonary involvement in female patients.
Collapse
Affiliation(s)
- S K Rakowski
- Department of Neurology, Massachusetts General Hospital, Boston, Massachusetts, USA
| | | | | | | | | | | |
Collapse
|
214
|
Affiliation(s)
- Peter B Crino
- Department of Neurology, University of Pennsylvania Medical Center, Philadelphia 19104, USA.
| | | | | |
Collapse
|
215
|
Hung CC, Su YN, Chien SC, Liou HH, Chen CC, Chen PC, Hsieh CJ, Chen CP, Lee WT, Lin WL, Lee CN. Molecular and clinical analyses of 84 patients with tuberous sclerosis complex. BMC MEDICAL GENETICS 2006; 7:72. [PMID: 16981987 PMCID: PMC1592085 DOI: 10.1186/1471-2350-7-72] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2006] [Accepted: 09/18/2006] [Indexed: 11/10/2022]
Abstract
BACKGROUND Tuberous sclerosis complex (TSC) is an autosomal dominant disease characterized by the development of multiple hamartomas in many internal organs. Mutations in either one of 2 genes, TSC1 and TSC2, have been attributed to the development of TSC. More than two-thirds of TSC patients are sporadic cases, and a wide variety of mutations in the coding region of the TSC1 and TSC2 genes have been reported. METHODS Mutational analysis of TSC1 and TSC2 genes was performed in 84 Taiwanese TSC families using denaturing high-performance liquid chromatography (DHPLC) and direct sequencing. RESULTS Mutations were identified in a total of 64 (76 %) cases, including 9 TSC1 mutations (7 sporadic and 2 familial cases) and 55 TSC2 mutations (47 sporadic and 8 familial cases). Thirty-one of the 64 mutations found have not been described previously. The phenotype association is consistent with findings from other large studies, showing that disease resulting from mutations to TSC1 is less severe than disease due to TSC2 mutation. CONCLUSION This study provides a representative picture of the distribution of mutations of the TSC1 and TSC2 genes in clinically ascertained TSC cases in the Taiwanese population. Although nearly half of the mutations identified were novel, the kinds and distribution of mutation were not different in this population compared to that seen in larger European and American studies.
Collapse
Affiliation(s)
- Chia-Cheng Hung
- Institute of Biomedical Engineering, College of Medicine and College of Engineering, National Taiwan University, Taipei, Taiwan
| | - Yi-Ning Su
- Department of Medical Genetics, National Taiwan University Hospital, Taipei, Taiwan
- Graduate Institute of Clinical Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Shu-Chin Chien
- Departments of Medical Genetics and Obstetrics and Gynecology, China Medical University Hospital, Taichung, Taiwan
| | - Horng-Huei Liou
- Department of Neurology, National Taiwan University Hospital, Taipei, Taiwan
- Department of Pharmacology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Chih-Chuan Chen
- Department of Neurology, National Taiwan University Hospital, Taipei, Taiwan
| | - Pau-Chung Chen
- Institute of Occupational Medicine and Industrial Hygiene, National Taiwan University College of Public Health, Taipei, Taiwan
| | - Chia-Jung Hsieh
- Institute of Occupational Medicine and Industrial Hygiene, National Taiwan University College of Public Health, Taipei, Taiwan
| | - Chih-Ping Chen
- Department of Obstetrics and Gynecology, Mackay Memorial Hospital, Taipei, Taiwan
| | - Wang-Tso Lee
- Department of Pediatrics, National Taiwan University Hospital, Taipei, Taiwan
| | - Win-Li Lin
- Institute of Biomedical Engineering, College of Medicine and College of Engineering, National Taiwan University, Taipei, Taiwan
| | - Chien-Nan Lee
- Department of Obstetrics and Gynecology, National Taiwan University Hospital, Taipei, Taiwan
| |
Collapse
|
216
|
Zaroff CM, Barr WB, Carlson C, LaJoie J, Madhavan D, Miles DK, Nass R, Devinsky O. Mental retardation and relation to seizure and tuber burden in tuberous sclerosis complex. Seizure 2006; 15:558-62. [PMID: 16935530 DOI: 10.1016/j.seizure.2006.06.010] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2006] [Revised: 06/10/2006] [Accepted: 06/26/2006] [Indexed: 12/18/2022] Open
Abstract
In patients with tuberous sclerosis complex (TSC), the high rates of mental retardation are associated with cortical tubers, seizure activity, and genetic factors. The goal of the study was to investigate the relationship between bilateral cortical tubers and seizure variables and mental retardation in individuals with TSC. The records of 27 patients with TSC (age 6 months to 33 years) undergoing neuropsychological assessment and the following clinical variables were examined: bilateral versus non-bilateral cortical tubers, the age of seizure onset, and presence of infantile spasms. Results were statistically analyzed. Bilateral cortical tubers (p=0.02) and early age of seizure onset (p=0.04) were significantly related to impaired cognitive functioning. Only one of the seven patients with normal cognitive functioning had bilateral tubers, whereas 13/21 patients with intellectual impairment had bilateral tubers. Patients with normal cognitive functioning experienced a mean age of seizure onset after 6 years. A trend was observed between infantile spasms and cognitive functioning (p=0.06); the lack of statistical significance likely reflects the small sample size. Neither age nor gender was related to cognitive status. Further investigation incorporating additional neuroimaging factors, antiepileptic treatment effects, and genetic variables, is needed.
Collapse
Affiliation(s)
- Charles M Zaroff
- NYU Medical Center, Neurology, 403 East 34th St, 4th Floor, New York, NY 10016, USA.
| | | | | | | | | | | | | | | |
Collapse
|
217
|
Jozwiak J, Jozwiak S. Giant Cells: Contradiction to Two-Hit Model of Tuber Formation? Cell Mol Neurobiol 2006; 27:251-61. [PMID: 16897363 DOI: 10.1007/s10571-006-9106-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2005] [Accepted: 03/08/2005] [Indexed: 12/25/2022]
Abstract
Tuberous sclerosis (TSC) is an autosomal dominant disease characterized by the formation of hamartomatous lesions in many organs, including brain, heart or kidneys. It has been found that TSC is caused by the mutation in one of the two tumor suppressor genes: TSC1 or TSC2, encoding hamartin and tuberin, respectively. According to Knudson's two-hit model of tumorigenesis, second-hit mutation and resulting loss of heterozygosity (LOH) of a tumor suppressor gene is necessary for tumor formation. In fact, LOH is commonly found in several types of hamartomas formed in the process of tuberous sclerosis, but, interestingly, not in brain lesions, containing characteristic giant cells. In this paper, we review literature covering origination of giant cells and present several hypotheses explaining why in spite of the presence of hamartin and tuberin, brain lesions form in TSC patients.
Collapse
Affiliation(s)
- Jaroslaw Jozwiak
- Department of Histology and Embryology, Center for Biostructure Research, Medical University of Warsaw ul., Chalubinskiego, Warsaw, Poland.
| | | |
Collapse
|
218
|
Choi JE, Chae JH, Hwang YS, Kim KJ. Mutational analysis of TSC1 and TSC2 in Korean patients with tuberous sclerosis complex. Brain Dev 2006; 28:440-6. [PMID: 16554133 DOI: 10.1016/j.braindev.2006.01.006] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2005] [Revised: 01/19/2006] [Accepted: 01/22/2006] [Indexed: 11/27/2022]
Abstract
Tuberous sclerosis complex (TSC) is an autosomal dominant disorder characterized by a broad phenotypic spectrum that includes seizures, mental retardation, renal dysfunction and dermatological abnormalities. TSC is caused by mutations affecting either of the tumor-suppressor genes TSC1 and TSC2. At least 495 mutations of TSC1 and TSC2 have been reported. Twenty-two males and 22 females who were diagnosed with TSC at the Seoul National University Children's Hospital between 1982 and 2002 were enrolled in the study. Forty-four patients were from different families and included nine familial cases and 35 sporadic cases. Denaturing high performance liquid chromatography and DNA sequencing analysis of TSC1 and TSC2 revealed 13 types of mutations (30%). One novel mutation of TSC1 and nine novel mutations of TSC2 were identified. The TSC1 mutation and one of the nine TSC2 mutations were missense mutations and seven of the nine TSC2 mutations caused truncation of proteins. One novel single nucleotide substitution was identified at the consensus splicing donor site of exon 39 (c.5,069-1G>A). This mutation is predicted to cause a splicing error. Of the TSC2 mutation loci, the correlation with cardiac rhabdomyoma was more significant when the mutation was in the C-terminal part of tuberin than the N-terminal part. This is the first extensive mutational analysis of TSC1 and TSC2 in Korean TSC patients.
Collapse
Affiliation(s)
- Ji-Eun Choi
- Department of Pediatrics, Borame Hospital affiliated to Seoul National University Hospital, 395 shindaebang-2-dong, Dongjak-gu, 156-707 Seoul, South Korea.
| | | | | | | |
Collapse
|
219
|
Abstract
Tuberous sclerosis is a serious inherited disease which poses major challenges for affected families and those caring for them. Identification of the genes causing the condition and study of their protein products has shed light on the pathogenesis of the disease and provided valuable new information about signalling pathways regulating protein synthesis and cell growth. There is now the exciting possibility of drug therapy for some of the manifestations of the disease.
Collapse
Affiliation(s)
- John R W Yates
- Department of Medical Genetics, University of Cambridge, Cambridge, UK.
| |
Collapse
|
220
|
Rendtorff ND, Bjerregaard B, Frödin M, Kjaergaard S, Hove H, Skovby F, Brøndum-Nielsen K, Schwartz M. Analysis of 65 tuberous sclerosis complex (TSC) patients by TSC2 DGGE, TSC1/TSC2 MLPA, and TSC1 long-range PCR sequencing, and report of 28 novel mutations. Hum Mutat 2006; 26:374-83. [PMID: 16114042 DOI: 10.1002/humu.20227] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Tuberous sclerosis complex (TSC) is a severe autosomal-dominant disorder characterized by the development of benign tumors (hamartomas) in many organs. It can lead to intellectual handicap, epilepsy, autism, and renal or heart failure. An inactivating mutation in either of two tumor-suppressor genes-TSC1 and TSC2-is the cause of this syndrome, with TSC2 mutations accounting for 80-90% of all mutations. Molecular diagnosis of TSC is challenging, since TSC1 and TSC2 consist of 21 and 41 coding exons, respectively, and the mutation spectrum is very heterogeneous. Here we report a new approach for detecting mutations in TSC: a denaturing gradient gel electrophoresis (DGGE) analysis for small TSC2 mutations, a multiplex ligation-dependent probe amplification (MLPA) analysis for large deletions and duplications in TSC1 or TSC2, and a long-range PCR/sequencing-based analysis for small TSC1 mutations. When applied in this order, the three methods provide a new sensitive and time- and cost-efficient strategy for the molecular diagnosis of TSC. We analyzed 65 Danish patients who had been clinically diagnosed with TSC, and identified pathogenic mutations in 51 patients (78%). These included 36 small TSC2 mutations, four large deletions involving TSC2, and 11 small TSC1 mutations. Twenty-eight of the small mutations are novel. For the missense mutations, we established a functional assay to demonstrate that the mutations impair TSC2 protein function. In conclusion, the strategy presented may greatly help small- and medium-sized laboratories in the pre- and postnatal molecular diagnosis of TSC.
Collapse
Affiliation(s)
- Nanna D Rendtorff
- Department of Medical Genetics, John F. Kennedy Institute, Glostrup, Denmark.
| | | | | | | | | | | | | | | |
Collapse
|
221
|
von der Brelie C, Waltereit R, Zhang L, Beck H, Kirschstein T. Impaired synaptic plasticity in a rat model of tuberous sclerosis. Eur J Neurosci 2006; 23:686-92. [PMID: 16487150 DOI: 10.1111/j.1460-9568.2006.04594.x] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Tuberous sclerosis complex (TSC) is a common hereditary disorder caused by mutations in either the TSC1 or TSC2 genes, and characterized by severe epilepsy, cerebral hamartomas and mental retardation. We have used rats that are heterozygous for an autosomal-dominant germline mutation in the TSC2 gene (TSC2+/- rats) to examine the consequences of TSC2 mutations for hippocampal synaptic plasticity. While basal synaptic transmission in the Schaffer collateral-CA1 synapse was not altered, paired-pulse plasticity was significantly enhanced in TSC2+/- rats (interpulse intervals 20-200 ms). Moreover, TSC2+/- rats exhibited a marked reduction of different forms of synaptic plasticity. Long-term potentiation (LTP) elicited following high-frequency tetanization of Schaffer collaterals was significantly decreased from 1.45 +/- 0.05-fold potentiation to 1.15 +/- 0.04 (measured after 60 min). This difference in LTP levels between TSC2+/- and wild-type rats also persisted in the presence of the gamma-aminobutyric acid (GABA)(A) receptor antagonist bicuculline. In addition to changed LTP, the level of long-term depression (LTD) elicited by different forms of low-frequency stimulation was significantly less in TSC2+/- rats. These results suggest that TSC2 mutations may cause hippocampal synapses to lose much of their potential for activity-dependent synaptic modification. An understanding of the underlying molecular pathways may suggest new therapeutic approaches aimed at inhibiting the development of the profound mental retardation in TSC.
Collapse
Affiliation(s)
- Christian von der Brelie
- Department of Epileptology, University of Bonn Medical Center, Sigmund-Freud-Strasse 25, 53105 Bonn, Germany
| | | | | | | | | |
Collapse
|
222
|
Becker AJ, Blümcke I, Urbach H, Hans V, Majores M. Molecular neuropathology of epilepsy-associated glioneuronal malformations. J Neuropathol Exp Neurol 2006; 65:99-108. [PMID: 16462201 DOI: 10.1097/01.jnen.0000199570.19344.33] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Glioneuronal malformations (malformations of cortical development [MCD]) include focal cortical dysplasias (FCD) as well as highly differentiated glioneuronal tumors (i.e. gangliogliomas) and constitute frequent findings in patients with pharmacoresistent focal epilepsies. Tailored resection strategies evolved as promising treatment options and allow a systematic neuropathologic and molecular biologic examination of the epileptogenic area in these patients. The histopathologic appearance and immunophenotype of glioneuronal lesions are, however, characterized by numerous similarities and suggest impaired proliferation, migration, and differentiation of neural precursor cells to play a pathogenetic role. Recent studies point toward molecular alterations within a variety of genes and pathways involved in development of the central nervous system, neuronal growth, and maturation. Compromised signaling within insulin- or reelin-transduction cascades are common findings and were associated with specific MCD entities. Unraveling pathogenic mechanisms may advance refined classification systems for epilepsy-associated malformations and open new avenues for the development of targeted treatment strategies in pharmacoresistent focal epilepsies associated with cortical malformations.
Collapse
Affiliation(s)
- Albert J Becker
- Department of Neuropathology, Bonn University Medical Center, Sigmund-Freud Strasse 25, D-53105 Bonn, Germany.
| | | | | | | | | |
Collapse
|
223
|
Abstract
There has been increasing awareness that there are behavioral phenotypes in tuberous sclerosis complex with neuropsychiatric symptom complex such as autistic disorder and attention-deficit hyperactivity disorder (ADHD). However, the neurobiologic basis of autistic disorder in tuberous sclerosis complex is still unknown. We studied two cohorts of children followed up since 1986 until 2003, one cohort with tuberous sclerosis complex and another cohort with autistic disorder, to determine the incidence of autistic disorder in tuberous sclerosis complex and the incidence of tuberous sclerosis complex in autistic disorder respectively. We established a Tuberous Sclerosis Complex Registry in 1985 at the University of Hong Kong. In 2004, 44 index cases (the male to female ratio was 0.75:1) were registered. Three had a positive family history of tuberous sclerosis complex. Thus, the total number of tuberous sclerosis complex cases was 47. We adopted the diagnostic criteria of tuberous sclerosis complex for case ascertainment. The period prevalence rate of tuberous sclerosis complex for children and adolescents aged < 20 years is 3.5 per 10,000 (on Hong Kong island, excluding the eastern region with 125,100 aged < 20 years in 2003). Of 44 cases with tuberous sclerosis complex, 7 had autistic disorder. Thus, the incidence of autistic disorder in tuberous sclerosis complex is 16%. During the 17-year period (1986-2003), we collected a database of 753 children (668 boys and 84 girls; male to female ratio 8:1) with autistic disorder and pervasive developmental disorders. For all children with autistic disorder or pervasive developmental disorders, we routinely examined for any features of tuberous sclerosis complex by looking for neurocutaneous markers such as depigmented spots, which appear in 50% of children with tuberous sclerosis complex by the age of 2 years. For those with infantile spasm or epilepsy, the clinical features of tuberous sclerosis complex were monitored regularly during follow-up. Of these, seven had tuberous sclerosis complex. Thus, the incidence of tuberous sclerosis complex in autistic disorder is 0.9%. All of these children are mentally retarded, with moderate to severe grades in an intellectual assessment conducted by a clinical psychologist. Future studies should be directed toward looking at the various behavioral phenotypes in tuberous sclerosis complex and defining these with standardized criteria to look for any real association with the underlying genetic mutation of TSC1 or TSC2 gene or even the site of tubers in the brain.
Collapse
Affiliation(s)
- Virginia Wong
- Division of Neurodevelopmental Paediatrics, Department of Paediatrics and Adolescent Medicine, The University of Hong Kong, Hong Kong, China.
| |
Collapse
|
224
|
Abstract
Tuberous sclerosis complex (TSC) is a multiorgan genetic disease caused by inactivation of either the TSC1 or TSC2 genes. The disorder typically has profound neurologic involvement and often presents early in life with epilepsy, developmental delay, mental retardation, and autism. These features are generally accepted to result from structural brain abnormalities that are found in patients with TSC. Although much progress has recently been made in discerning the function(s) of the TSC genes, many questions remain as to the role of these genes in brain development and homeostasis. This review will summarize recent progress and suggest future avenues of basic science research.
Collapse
Affiliation(s)
- Kevin C Ess
- Departments of Neurology and Pediatrics, Washington University School of Medicine, St Louis, MO, USA.
| |
Collapse
|
225
|
Nellist M, Sancak O, Goedbloed MA, van Veghel-Plandsoen M, Maat-Kievit A, Lindhout D, Eussen BH, de Klein A, Halley DJJ, van den Ouweland AMW. Large deletion at the TSC1 locus in a family with tuberous sclerosis complex. ACTA ACUST UNITED AC 2006; 9:226-30. [PMID: 16225402 DOI: 10.1089/gte.2005.9.226] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Tuberous sclerosis complex (TSC) is an autosomal dominant disorder characterized by seizures, mental retardation and the development of hamartomas in a variety of organs and tissues. The disease is caused by mutations in either the TSC1 gene on chromosome 9q34, or the TSC2 gene on chromosome 16p13.3. Here we describe a deletion encompassing the TSC1 gene and two neighboring transcripts on chromosome 9q34 in six affected individuals from a family with TSC. To our knowledge, this is the first report of such a large deletion at the TSC1 locus and indicates that screening for similar mutations at the TSC1 locus is warranted in individuals with TSC.
Collapse
Affiliation(s)
- M Nellist
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
| | | | | | | | | | | | | | | | | | | |
Collapse
|
226
|
Goncharova EA, Goncharov DA, Spaits M, Noonan DJ, Talovskaya E, Eszterhas A, Krymskaya VP. Abnormal growth of smooth muscle-like cells in lymphangioleiomyomatosis: Role for tumor suppressor TSC2. Am J Respir Cell Mol Biol 2006; 34:561-72. [PMID: 16424383 PMCID: PMC2644221 DOI: 10.1165/rcmb.2005-0300oc] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The TSC1 and TSC2 proteins, which function as a TSC1/TSC2 tumor suppressor complex, are associated with lymphangioleiomyomatosis (LAM), a genetic disorder characterized by the abnormal growth of smooth muscle-like cells in the lungs. The precise molecular mechanisms that modulate LAM cell growth remain unknown. We demonstrate that TSC2 regulates LAM cell growth. Cells dissociated from LAM nodules from the lungs of five different patients with LAM have constitutively activated S6K1, hyperphosphorylated ribosomal protein S6, activated Erk, and increased DNA synthesis compared with normal cells from the same patients. These effects were augmented by PDGF stimulation. Akt activity was unchanged in LAM cells. Rapamycin, a specific S6K1 inhibitor, abolished increased LAM cell growth. The full-length TSC2 was necessary for inhibition of S6 hyperphosphorylation and DNA synthesis in LAM cells, as demonstrated by co-microinjection of the C-terminus, which contains the GTPase activating protein homology domain, and the N-terminus, which binds TSC1. Our data demonstrate that increased LAM cell growth is associated with constitutive S6K1 activation, which is extinguishable by TSC2 expression. Loss of TSC2 GAP activity or disruption of the TSC1/TSC2 complex dysregulates S6K1 activation, which leads to abnormal cell proliferation associated with LAM disease.
Collapse
Affiliation(s)
- Elena A Goncharova
- Pulmonary, Allergy and Critical Care Division, Department of Medicine, University of Pennsylvania, 421 Curie Boulevard, BRB II/III, Philadelphia, PA 19104-6160, USA.
| | | | | | | | | | | | | |
Collapse
|
227
|
McCall T, Chin SS, Salzman KL, Fults DW. Tuberous sclerosis: a syndrome of incomplete tumor suppression. Neurosurg Focus 2006; 20:E3. [PMID: 16459993 DOI: 10.3171/foc.2006.20.1.4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Tuberous sclerosis (TS) is a congenital neurocutaneous syndrome (or phacomatosis) characterized by widespread development of hamartomas in multiple organs. For affected individuals, neurological and psychiatric complications are the most disabling and lethal features. Although the clinical phenotype of TS is complex, only three lesions characterize the neuropathological features of the disease: cortical tubers, subependymal nodules, and subependymal giant cell astrocytomas. The latter is a benign brain tumor of mixed neuronal and glial origin. Tuberous sclerosis is caused by loss-of-function mutations in one of two genes, TSC1 or TSC2. The normal cellular proteins encoded by these genes, hamartin and tuberin, respectively, form a heterodimer that suppresses cell growth in the central nervous system by dampening the phosphatidylinositol 3–kinase signal transduction pathway. The authors review the clinical and neuropathological features of TS as well as recent research into the molecular biology of this disease. Through this work, investigators are beginning to resolve the paradoxical findings that malignant cancers seldom arise in patients with TS, even though the signaling molecules involved are key mediators of cancer cell growth.
Collapse
Affiliation(s)
- Todd McCall
- Department of Neurosurgery, University of Utah School of Medicine, Salt Lake City, Utah 84132-2303, USA
| | | | | | | |
Collapse
|
228
|
Chen CP, Su YN, Hung CC, Shih JC, Wang W. Novel Mutation in the TSC2 Gene Associated with Prenatally Diagnosed Cardiac Rhabdomyomas and Cerebral Tuberous Sclerosis. J Formos Med Assoc 2006; 105:599-603. [PMID: 16877242 DOI: 10.1016/s0929-6646(09)60157-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Cardiac rhabdomyomas are prenatal echocardiographic markers for tuberous sclerosis complex (TSC). TSC is caused by mutations in the genes TSC1 and TSC2. We report a 28-year-old, gravida 5, para 2, woman with an uncomplicated pregnancy until prenatal ultrasound at 34 weeks' gestation revealed fetal cardiac tumors. Ultrafast magnetic resonance imaging (MRI) at 36 weeks' gestation showed cardiac rhabdomyomas and small subependymal tubers. At 39 weeks' gestation, a 2,262 g female infant was delivered uneventfully. Postnatal echocardiography confirmed cardiac rhabdomyomas and MRI verified small cerebral subependymal tubers. Mutational analysis of TSC1 and TSC2 genes using denaturing high-performance liquid chromatography and direct sequencing of the genes was performed and revealed that the parents had wildtype DNA, while the proband was heterozygous for a novel de novo nonsense mutation, c.4830G >A, in exon 36 of the TSC2 gene, resulting in a change of codon 1610 TGG (tryptophan) to TGA (stop codon). The mutation predicted a W1610X premature termination of the tuberin protein. These findings support an association between a TSC2 de novo nonsense mutation and prenatally detected cardiac rhabdomyomas and cerebral tuberous sclerosis. Familial molecular analysis of TSC1 and TSC2 in cases with prenatally diagnosed cardiac rhabdomyomas and cerebral tuberous sclerosis lesions is helpful in prenatal diagnosis and genetic counseling.
Collapse
Affiliation(s)
- Chih-Ping Chen
- Department of Obstetrics and Gynecology, Mackay Memorial Hospital, Institute of Clinical Nursing, School of Nursing, National Yang-Ming University, Taipei, Taiwan.
| | | | | | | | | |
Collapse
|
229
|
Astrinidis A, Henske EP. Tuberous sclerosis complex: linking growth and energy signaling pathways with human disease. Oncogene 2005; 24:7475-81. [PMID: 16288294 DOI: 10.1038/sj.onc.1209090] [Citation(s) in RCA: 157] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The most exciting advances in the tuberous sclerosis complex (TSC) field occurred in 1993 and 1997 with the cloning of the TSC2 and TSC1 genes, respectively, and in 2003 with the identification of Rheb as the target of tuberin's (TSC2) GTPase activating protein (GAP) domain. Rheb has a dual role: it activates mTOR and inactivates B-Raf. Activation of mTOR leads to increased protein synthesis through phosphorylation of p70S6K and 4E-BP1. Upon insulin or growth factor stimulation, tuberin is phosphorylated by several kinases, including AKT/PKB, thereby suppressing its GAP activity and activating mTOR. Phosphorylation of hamartin (TSC1) by CDK1 also negatively regulates the activity of the hamartin/tuberin complex. Despite these biochemical advances, exactly how mutations in TSC1 or TSC2 lead to the clinical manifestations of TSC is far from being understood. Two of the most unusual phenotypes in TSC are the apparent metastasis of benign cells carrying TSC1 and TSC2 mutations, resulting in pulmonary lymphangiomyomatosis, and the ability of cells with TSC1 or TSC2 mutations to differentiate into the separate components of renal angiomyolipomas (vessels, smooth muscle and fat). We will discuss how the TSC signaling pathways are affected by mutations in TSC1 or TSC2, focusing on how these mutations may lead to the renal and pulmonary manifestations of TSC.
Collapse
|
230
|
Ichikawa T, Wakisaka A, Daido S, Takao S, Tamiya T, Date I, Koizumi S, Niida Y. A case of solitary subependymal giant cell astrocytoma: two somatic hits of TSC2 in the tumor, without evidence of somatic mosaicism. J Mol Diagn 2005; 7:544-9. [PMID: 16237225 PMCID: PMC1888498 DOI: 10.1016/s1525-1578(10)60586-7] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Subependymal giant cell astrocytoma (SEGA) is a unique brain tumor arising in tuberous sclerosis complex (TSC), an autosomal dominant inherited phacomatosis. There are several case reports of solitary SEGA without any other manifestations of TSC. Usually these cases are thought to be forme fruste of TSC due to somatic mosaicism. However, no previous reports have used molecular methodology to fully investigate mutations in TSC genes or the possibility of somatic mosaicism. Here, we report a 20-year-old woman with a brain tumor. Pathological diagnosis was consistent with SEGA, but comprehensive clinical screening found no other lesions indicative of TSC. Molecular analysis of the tumor revealed loss of heterozygosity and allelic mutation (5228G>A, R1743Q) of TSC2. To detect the small fraction of mosaic mutation in somatic cells, we developed a highly sensitive new method: triple-nested polymerase chain reaction-restriction fragment length polymorphism. The identical TSC2 missense mutation was not detected in any other tissues from the same patient, including peripheral blood, buccal mucosa, urinary sediment, nail, and hair. According to these results, this patient should be considered as having SEGA that developed from two somatic hit mutations in TSC2, rather than being a TSC2 patient with a very small fraction of somatic mosaicism.
Collapse
Affiliation(s)
- Tomotsugu Ichikawa
- Department of Neurological Surgery, Okayama University Graduate School of Medicine and Dentistry, Japan
| | | | | | | | | | | | | | | |
Collapse
|
231
|
Kwiatkowski DJ, Manning BD. Tuberous sclerosis: a GAP at the crossroads of multiple signaling pathways. Hum Mol Genet 2005; 14 Spec No. 2:R251-8. [PMID: 16244323 DOI: 10.1093/hmg/ddi260] [Citation(s) in RCA: 307] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Tuberous sclerosis complex (TSC) is an autosomal dominant disorder that is characterized by benign tumors (hamartomas and hamartias) involving multiple organ systems, due to inactivating mutations in TSC1 or TSC2. Here, we review recent advances in our understanding of the growth and signaling functions of the TSC1 and TSC2 proteins. Led by seminal studies in Drosophila, the TSC1/TSC2 complex has been positioned in an ancestrally conserved signaling pathway that regulates cell growth. TSC1/TSC2 receives inputs from at least three major signaling pathways in the form of kinase-mediated phosphorylation events that regulate its function as a GTPase activating protein (GAP): the PI3K-Akt pathway, the ERK1/2-RSK1 pathway and the LKB1-AMPK pathway. TSC1/TSC2 functions as a GAP towards Rheb, which is a major regulator of the mammalian target of rapamycin (mTOR). In the absence of either TSC1 or TSC2, high levels of Rheb-GTP lead to constitutive activation of mTOR-raptor signaling, thereby leading to enhanced and deregulated protein synthesis and cell growth. As a specific inhibitor of mTOR, rapamycin has therapeutic potential for the treatment of TSC hamartomas.
Collapse
Affiliation(s)
- David J Kwiatkowski
- Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, One Blackfan Circle, 6th Floor, Room 216, Boston, MA 02115, USA.
| | | |
Collapse
|
232
|
Abstract
Neurocutaneous syndromes are disorders characterized by a neurological abnormality and cutaneous manifestations. Three of the more common neurocutaneous syndromes are Sturge-Weber syndrome, tuberous sclerosis, and neurofibromatosis. This review focuses on the cognitive and behavioral features of these syndromes.
Collapse
Affiliation(s)
- Charles M Zaroff
- Comprehensive Epilepsy Center, New York University, 403 East 34th Street, New York, NY 10016, USA.
| | | |
Collapse
|
233
|
Mak BC, Kenerson HL, Aicher LD, Barnes EA, Yeung RS. Aberrant beta-catenin signaling in tuberous sclerosis. THE AMERICAN JOURNAL OF PATHOLOGY 2005; 167:107-16. [PMID: 15972957 PMCID: PMC1603434 DOI: 10.1016/s0002-9440(10)62958-6] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The pathology associated with tuberous sclerosis complex (TSC) shows diverse phenotypes that suggest abnormal signaling of multiple pathways. Besides the negative regulatory role of the TSC1/TSC2 proteins on mTOR, we have reported an effect on beta-catenin signaling at the level of the degradation complex in vitro. The TSC1/TSC2 complex associates with GSK3 and Axin and promotes beta-catenin degradation to inhibit Wnt-stimulated TCF/LEF-dependent transcription. Here, we show that beta-catenin and its effectors, cyclin D1 and connexin 43, were up-regulated in TSC-related angiomyolipomas and lymphangioleiomyomatosis. This was supported by the failure of three disease-causing TSC2 missense mutants to inhibit Wnt signaling. Further, the interaction between TSC1/TSC2 and components of the beta-catenin degradation complex was dependent on Wnt stimulation such that binding of tuberin to GSK3 and Axin was reduced in the presence of Wnt whereas the tuberin-Dishevelled interaction was increased. GSK3 activity played a role in regulating the assembly/stability of the degradation complex. Inhibition of GSK3 by lithium chloride reduced its association with TSC1 whereas disruption of GSK3-phosphorylation sites in TSC1 reduced interaction between TSC2 and TSC1. Collectively, our data provide further evidence that beta-catenin signaling plays a role in TSC pathogenesis in vivo and suggest a novel role of GSK3 in modulating the TSC1/TSC2 complex through TSC1 phosphorylation.
Collapse
Affiliation(s)
- Baldwin C Mak
- Department of Surgery, University of Washington, 1959 NE Pacific St., Box 356410, Seattle, WA 98195, USA
| | | | | | | | | |
Collapse
|
234
|
Jozwiak J, Jozwiak S. Giant Cells: Contradiction to Two-Hit Model of Tuber Formation? Cell Mol Neurobiol 2005; 25:795-805. [PMID: 16133934 DOI: 10.1007/s10571-005-4932-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2005] [Accepted: 03/08/2005] [Indexed: 12/20/2022]
Abstract
1. Tuberous sclerosis (TSC) is an autosomal dominant disease characterized by the formation of hamartomatous lesions in many organs, including brain, heart or kidneys. It has been found that TSC is caused by the mutation in one of two tumor suppressor genes: TSC1 or TSC2, encoding hamartin and tuberin, respectively. 2. According to Knudson's two-hit model of tumorigenesis, second-hit mutation and resulting loss of heterozygosity (LOH) of a tumor suppressor gene is necessary for tumor formation. In fact, LOH is commonly found in several types of hamartomas formed in the process of tuberous sclerosis, but, interestingly, not in brain lesions, containing characteristic giant cells. 3. In the present paper we review literature covering origination of giant cells and present several hypotheses explaining why in spite of the presence of hamartin and tuberin, brain lesions form in TSC patients.
Collapse
Affiliation(s)
- Jaroslaw Jozwiak
- Department of Histology and Embryology, Center for Biostructure Research, Medical University of Warsaw, and Department of Pediatric Neurology, Children's Memorial Hospital, Warsaw, Poland.
| | | |
Collapse
|
235
|
Abstract
Hereditary origin of a tumor helps toward early discovery of its mutated gene; for example, it supports the compilation of a DNA panel from index cases to identify that gene by finding mutations in it. The gene for a hereditary tumor may contribute also to common tumors. For some syndromes, such as hereditary paraganglioma, several genes can cause a similar syndrome. For other syndromes, such as multiple endocrine neoplasia 2, one gene supports variants of a syndrome. Onset usually begins earlier and in more locations with hereditary than sporadic tumors. Mono- or oligoclonal ("clonal") tumor usually implies a postnatal delay, albeit less delay than for sporadic tumor, to onset and potential for cancer. Hormone excess from a polyclonal tissue shows onset at birth and no benefit from subtotal ablation of the secreting organ. Genes can cause neoplasms through stepwise loss of function, gain of function, or combinations of these. Polyclonal hormonal excess reflects abnormal gene dosage or effect, such as activation or haploinsufficiency. Polyclonal hyperplasia can cause the main endpoint of clinical expression in some syndromes or can be a precursor to clonal progression in others. Gene discovery is usually the first step toward clarifying the molecule and pathway mutated in a syndrome. Most mutated pathways in hormone excess states are only partly understood. The bases for tissue specificity of hormone excess syndromes are usually uncertain. In a few syndromes, tissue selectivity arises from mutation in the open reading frame of a regulatory gene (CASR, TSHR) with selective expression driven by its promoter. Polyclonal excess of a hormone is usually from a defect in the sensor system for an extracellular ligand (e.g., calcium, glucose, TSH). The final connections of any of these polyclonal or clonal pathways to hormone secretion have not been identified. In many cases, monoclonal proliferation causes hormone excess, probably as a secondary consequence of accumulation of cells with coincidental hormone-secretory ability.
Collapse
Affiliation(s)
- Stephen J Marx
- Metabolic Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases/NIH, Building 10, Room 9C-101, 10 Center Drive, MSC 1802, Bethesda, MD 20892-1802, USA.
| | | |
Collapse
|
236
|
Henske EP. Tuberous sclerosis and the kidney: from mesenchyme to epithelium, and beyond. Pediatr Nephrol 2005; 20:854-7. [PMID: 15856327 DOI: 10.1007/s00467-004-1795-3] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/24/2004] [Accepted: 11/30/2004] [Indexed: 01/14/2023]
Abstract
The renal manifestations of tuberous sclerosis complex (TSC) are remarkably diverse, including polycystic kidney disease, oncocytomas, renal cell carcinomas, and both benign and malignant angiomyolipomas. All of these occur in children as well as adults with TSC. Benign angiomyolipomas, which can cause spontaneous life-threatening hemorrhage, are by far the most prevalent and the greatest source of morbidity. What is particularly unusual about TSC, setting it apart from virtually all other inherited forms of renal disease, is the abnormalities of both mesenchymal cells (angiomyolipomas) and epithelial cells (cysts, oncocytomas, and carcinomas). Recently, the TSC1/TSC2 protein complex was shown to inhibit the kinase mTOR (mammalian target of rapamycin). This places TSC1/TSC2 at center stage in signaling pathways that regulate cell growth. Furthermore, recent advances in TSC1/TSC2 signaling open the door for targeted therapy for TSC patients. Here, we will address the genetic, cellular and biochemical mechanisms that may contribute to the unusually broad spectrum of renal disease in cells with TSC1 or TSC2 mutations, and consider how the TSC signaling pathways may be linked to other renal diseases such as polycystic kidney disease and renal cell carcinoma.
Collapse
|
237
|
Abstract
Neurofibromatoses and tuberous sclerosis have specific genetic epidemiology, diagnostic criteria and management. These diseases are autosomal dominant disorders linked to mutations on tumour suppressor genes. Their management is mainly clinically oriented and aimed at managing potential complications.
Collapse
Affiliation(s)
- P Wolkenstein
- Service de Dermatologie, Hôpital Henri-Mondor, 51 avenue du Maréchal de Lattre de Tassigny, 94010 Créteil
| |
Collapse
|
238
|
|
239
|
Wilson C, Idziaszczyk S, Parry L, Guy C, Griffiths DFR, Lazda E, Bayne RAL, Smith AJH, Sampson JR, Cheadle JP. A mouse model of tuberous sclerosis 1 showing background specific early post-natal mortality and metastatic renal cell carcinoma. Hum Mol Genet 2005; 14:1839-50. [PMID: 15888477 DOI: 10.1093/hmg/ddi190] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Tuberous sclerosis complex (TSC) is an autosomal dominant disorder caused by mutations in either the TSC1 or the TSC2 genes and characterized by the development of benign hamartomatous growths in multiple organ systems. We have inactivated Tsc1 in the mouse germ line by gene targeting in ES cells and confirmed that the mutant allele (Tsc1-) has a recessive embryonic lethal phenotype. We found that a significant number (approximately 27%) of heterozygous (Tsc1+/-) mice on the C57BL/6 background died before weaning (P = 0.014) and show that these mice die in the post-natal period (P = 0.033), normally at 1-2 days, from unknown causes. Forty-four percent (7/16) of Tsc1+/- mice on a C3H background developed macroscopically visible renal lesions as early as 3-6 months, increasing to 95% (37/39) by 15-18 months. Renal lesions progressed from cysts through cystadenomas to solid carcinomas. Eighty percent (16/20) of Tsc1+/- mice on a Balb/c background exhibited solid renal cell carcinomas (RCC) by 15-18 months and in 41%, RCCs were > or = 5 mm, resulting in grossly deformed kidneys. Some RCCs had a sarcomatoid morphology of spindle cells in whorled patterns and metastasized to the lungs. We detected loss of the wild-type Tsc1 allele and elevated levels of p-mTOR and p-S6 in lesions from Tsc1+/- mice. This new murine model of hamartin deficiency exhibits a more severe phenotype than existing models.
Collapse
Affiliation(s)
- Catherine Wilson
- Department of Medical Genetics, Cardiff University, Heath Park, Cardiff CF14 4XN, UK
| | | | | | | | | | | | | | | | | | | |
Collapse
|
240
|
Otsubo H, Iida K, Oishi M, Okuda C, Ochi A, Pang E, Weiss SK, Rutka JT, Chuang SH, Snead OC. Neurophysiologic findings of neuronal migration disorders: intrinsic epileptogenicity of focal cortical dysplasia on electroencephalography, electrocorticography, and magnetoencephalography. J Child Neurol 2005; 20:357-63. [PMID: 15921239 DOI: 10.1177/08830738050200041501] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We define specific neurophysiologic characteristics for focal cortical dysplasia, a neuronal migration disorder. We reviewed data from published reports and our patients with focal cortical dysplasia. Our patients underwent preoperative scalp video-electroencephalography (EEG), magnetic resonance imaging (MRI), magnetoencephalography, and intraoperative or extraoperative electrocorticography monitoring. Scalp EEG showed trains of rhythmic epileptiform spike or sharp waves. Positive spikes correlated with early seizure onset, MRI lesion around the rolandic fissure, hemiparesis, and a less favorable outcome. Interictal electrocorticography showed continuous epileptogenic discharges: repetitive electrographic seizures and bursting discharges or continuous or quasicontinuous rhythmic spiking. Ictal electrocorticography showed paroxysmal fast and/or repetitive spiking. Magnetoencephalography showed clustered spike sources within and extending from the lesion. Cortical stimulation gave more frequent, lower-threshold afterdischarges and higher-threshold primary motor function. Focal cortical dysplasias are highly and intrinsically epileptogenic. For surgical seizure control, EEG, electrocorticography, and magnetoencephalography must delineate the intrinsic epileptogenic zone within and extending from the focal cortical dysplasia identified by MRI.
Collapse
Affiliation(s)
- Hiroshi Otsubo
- Division of Neurology, The Hospital for Sick Children, Toronto, ON, Canada.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
241
|
Sancak O, Nellist M, Goedbloed M, Elfferich P, Wouters C, Maat-Kievit A, Zonnenberg B, Verhoef S, Halley D, van den Ouweland A. Mutational analysis of the TSC1 and TSC2 genes in a diagnostic setting: genotype – phenotype correlations and comparison of diagnostic DNA techniques in Tuberous Sclerosis Complex. Eur J Hum Genet 2005; 13:731-41. [PMID: 15798777 DOI: 10.1038/sj.ejhg.5201402] [Citation(s) in RCA: 309] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Tuberous sclerosis complex (TSC) is an autosomal dominant disorder characterised by the development of hamartomas in multiple organs and tissues. TSC is caused by mutations in either the TSC1 or TSC2 gene. We searched for mutations in both genes in a cohort of 490 patients diagnosed with or suspected of having TSC using a combination of denaturing gradient gel electrophoresis, single-strand conformational polymorphism, direct sequencing, fluorescent in situ hybridisation and Southern blotting. We identified pathogenic mutations in 362 patients, a mutation detection rate of 74%. Of these 362 patients, 276 had a definite clinical diagnosis of TSC and in these patients 235 mutations were identified, a mutation detection rate of 85%. The ratio of TSC2:TSC1 mutations was 3.4:1. In our cohort, both TSC1 mutations and mutations in familial TSC2 cases were associated with phenotypes less severe than de novo TSC2 mutations. Interestingly, consistent with other studies, the phenotypes of the patients in which no mutation was identified were, overall, less severe than those of patients with either a known TSC1 or TSC2 mutation.
Collapse
Affiliation(s)
- Ozgur Sancak
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
| | | | | | | | | | | | | | | | | | | |
Collapse
|
242
|
Abstract
We reviewed the epileptogenic cortical malformations for which a causative gene has been cloned or a linkage obtained. X-linked bilateral periventricular nodular heterotopia (BPNH) consists of typical BPNH with epilepsy in female patients and prenatal lethality in most males. About 90% of patients have focal epilepsy. Filamin A mutations have been reported in all families and in approximately 20% of sporadic patients. A rare recessive form of BPNH also has been reported. Most cases of lissencephaly-pachygyria are caused by mutations of LIS1 and XLIS genes. LIS1 mutations cause a more severe malformation posteriorly. Most children have isolated lissencephaly, with severe developmental delay and infantile spasms, but milder phenotypes have been recorded. XLIS usually causes anteriorly predominant lissencephaly in male patients and subcortical band heterotopia (SBH) in female patients. Thickness of the band and severity of pachygyria correlate with the likelihood of developing Lennox-Gastaut syndrome. Mutations of the coding region of XLIS are found in all reported pedigrees and in 50% of sporadic female patients with SBH. Autosomal recessive lissencephaly with cerebellar hypoplasia; accompanied by severe delay, hypotonia, and seizures, has been associated with mutations of the RELN gene. Schizencephaly has a wide anatomoclinical spectrum, including focal epilepsy in most patients. Familial occurrence is rare. Initial reports of heterozygous mutations in the EMX2 gene need confirmation. Among several syndromes featuring polymicrogyria, bilateral perisylvian polymicrogyria shows genetic heterogeneity, including linkage to Xq28 in some pedigrees, autosomal recessive inheritance in others, and association with 22q11.2 deletion in some patients. About 65% of patients have severe epilepsy, often Lennox-Gastaut syndrome. Recessive bilateral frontal polymicrogyria has been linked to chromosome 16q12.2-21.
Collapse
Affiliation(s)
- Renzo Guerrini
- Epilepsy, Neurophysiology and Neurogenetics Unit, Division of Child Neurology and Psychiatry, University of Pisa and Research Institute Stella Maris Foundation, Pisa, Italy.
| |
Collapse
|
243
|
Bolton PF. Neuroepileptic correlates of autistic symptomatology in tuberous sclerosis. ACTA ACUST UNITED AC 2005; 10:126-31. [PMID: 15362169 DOI: 10.1002/mrdd.20024] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Tuberous sclerosis is a genetic condition that is strongly associated with the development of an autism spectrum disorder. However, there is marked variability in expression, and only a subset of children with tuberous sclerosis develop autism spectrum disorder. Clarification of the mechanisms that underlie the association and variability in expression will potentially throw light on the biological processes involved in the etiology of idiopathic forms of autism spectrum disorder. Current evidence indicates that the likelihood of a child with tuberous sclerosis developing an autism spectrum disorder is greater if the child has a mutation in the TSC2 gene, although autism can and does develop in children with TSC1 mutations. The likelihood is also greater if the child has early-onset infantile spasms that are difficult to control, especially if there is an epileptiform focus in the temporal lobes. The emerging evidence is consistent with the notion that early onset electrophysiological disturbances within the temporal lobes (and perhaps other locations) has a deleterious effect on the development and establishment of key social cognitive representations concerned with processing social information, perhaps especially from faces. However, alternative mechanisms to account for the findings cannot yet be ruled out. Future research will have to employ prospective longitudinal designs and treatment trials to clarify the processes involved.
Collapse
Affiliation(s)
- Patrick F Bolton
- Department of Child Psychiatry and Centre for Social, Genetic and Developmental Psychiatry, The Institute of Psychiatry, Kings College, Denmark Hill, London SE5 8AF, UK.
| |
Collapse
|
244
|
Milunsky A, Shim SH, Ito M, Jaekle RK, Bassett LL, Brumund MR, Milunsky JM. Precise prenatal diagnosis of tuberous sclerosis by sequencing the TSC2 gene. Prenat Diagn 2005; 25:582-5. [PMID: 16032769 DOI: 10.1002/pd.1197] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND The presumptive prenatal diagnosis of tuberous sclerosis (TSC) previously depended upon fetal imaging. Cloning of the two TSC genes (TSC1 and TSC2) now enables precise molecular diagnosis by gene sequencing. We used this approach for the prenatal diagnosis of a fetus showing multiple intracardiac tumors. METHODS DNA extracted from cultivated amniotic fluid cells underwent sequencing of all coding regions and exon-intron boundaries of the TSC1 and TSC2 genes. RESULTS A mutation (R611Q) was found in exon 16 of the TSC2 gene. Thus far, neither clinically unaffected parents has provided blood samples for mutation analysis. CONCLUSION For the first time, mutation analysis of a TSC gene enabled a precise prenatal diagnosis.
Collapse
Affiliation(s)
- Aubrey Milunsky
- Center for Human Genetics, Boston University School of Medicine, Boston, MA 02118, USA.
| | | | | | | | | | | | | |
Collapse
|
245
|
Abstract
The "phakomatosis" concept was formulated early in the twentieth century by the ophthalmologist van der Hoeve. He included 3 disorders in the group-neurofibromatosis, tuberous sclerosis complex, and von Hippel-Lindau syndrome--on the basis of the occurrence of patchy ophthalmologic manifestations in each disorder. Since the name was coined, much has been learned about the pathogenesis of these 3 disorders. It is clear that 2 of them--neurofibromatosis and tuberous sclerosis--are collective terms for multiple disorders. Each of the conditions is caused by distinct genetic defects, with little commonality in terms of protein function. Yet, in some respects, the disorders share a pathogenetic mechanism, that of the tumor suppressor gene. This review will briefly describe these disorders in light of what has been learned about underlying molecular pathogenesis. In each case, genetic testing is beginning to be available; principles of the use of genetic tests will be described.
Collapse
Affiliation(s)
- Bruce R Korf
- Department of Genetics, University of Alabama at Birmingham, Birmingham, AL 35294-0024, USA.
| |
Collapse
|
246
|
Abstract
The study of hereditary tumor syndromes has laid a solid foundation toward understanding the genetic basis of cancer. One of the latest examples comes from the study of tuberous sclerosis complex (TSC). As a member of the phakomatoses, TSC is characterized by the appearance of benign tumors, most notably in the central nervous system, kidney, heart, lung, and skin. While classically described as "hamartomas," the pathology of the lesions has features suggestive of abnormal cellular proliferation, size, differentiation, and migration. Occasionally, tumors progress to become malignant (i.e., renal cell carcinoma). The genetic basis of this disease has been attributed to mutations in one of two unlinked genes, TSC1 and TSC2. Cells undergo bi-allelic inactivation of either gene to give rise to tumors in a classic tumor suppressor "two-hit" paradigm. The functions of the TSC1 and TSC2 gene products, hamartin and tuberin, respectively, have remained ill defined until recently. Genetic, biochemical, and biologic analyses have highlighted their role as negative regulators of the mTOR signaling pathway. Tuberin, serving as a substrate of AKT and AMPK, mediates mTOR activity by coordinating inputs from growth factors and energy availability in the control of cell growth, proliferation, and survival. Emerging evidence also suggests that the TSC 1/2 complex may play a role in modulating the activity of beta-catenin and TGFbeta. These findings provide novel functional links between the TSC genes and other tumor suppressors responsible for Cowden's disease (PTEN), Peutz-Jeghers syndrome (LKB1), and familial polyposis (APC). Common sporadic cancers such as prostate, lung, colon, endometrium, and breast have ties to these genes, highlighting the potential role of the TSC proteins in human cancers. Rapamycin, a specific mTOR inhibitor, has potent antitumoral activities in preclinical models of TSC and is currently undergoing phase I/II clinical studies.
Collapse
Affiliation(s)
- Baldwin C Mak
- Department of Surgery, University of Washington, Seattle, Washington 98195, USA
| | | |
Collapse
|
247
|
Melean G, Sestini R, Ammannati F, Papi L. Genetic insights into familial tumors of the nervous system. AMERICAN JOURNAL OF MEDICAL GENETICS PART C-SEMINARS IN MEDICAL GENETICS 2004; 129C:74-84. [PMID: 15264275 DOI: 10.1002/ajmg.c.30022] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
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.
Collapse
Affiliation(s)
- German Melean
- Medical Genetics Unit, Department of Clinical Physiology, University of Florence, Viale Pieraccini 6, 50139 Florence, Italy
| | | | | | | |
Collapse
|
248
|
Abstract
The evolutionarily conserved checkpoint protein kinase, TOR (target of rapamycin), has emerged as a major effector of cell growth and proliferation via the regulation of protein synthesis. Work in the last decade clearly demonstrates that TOR controls protein synthesis through a stunning number of downstream targets. Some of the targets are phosphorylated directly by TOR, but many are phosphorylated indirectly. In this review, we summarize some recent developments in this fast-evolving field. We describe both the upstream components of the signaling pathway(s) that activates mammalian TOR (mTOR) and the downstream targets that affect protein synthesis. We also summarize the roles of mTOR in the control of cell growth and proliferation, as well as its relevance to cancer and synaptic plasticity.
Collapse
Affiliation(s)
- Nissim Hay
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, 60607, USA.
| | | |
Collapse
|
249
|
Abstract
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.
Collapse
Affiliation(s)
- E Steve Roach
- Department of Neurology, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA.
| | | |
Collapse
|
250
|
Au KS, Williams AT, Gambello MJ, Northrup H. Molecular genetic basis of tuberous sclerosis complex: from bench to bedside. J Child Neurol 2004; 19:699-709. [PMID: 15563017 DOI: 10.1177/08830738040190091101] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Tuberous sclerosis complex is an autosomal dominant disease of benign tumors occurring in multiple organ systems of the body. Either of two genes, TSC1 or TSC2, can be mutated, resulting in the tuberous sclerosis complex phenotype. The protein products of the tuberous sclerosis complex genes, hamartin (TSC1) and tuberin (TSC2), have been discovered to play important roles in several cell-signaling pathways. Knowledge regarding the function of the tuberin-hamartin complex has led to therapeutic intervention trials. Numerous pathogenic mutations have been elucidated in individuals affected with tuberous sclerosis complex. Information on the type and distribution of nearly 1000 mutations in the two genes is discussed. Mosaicism for tuberous sclerosis complex mutations has been documented, complicating provision of genetic counseling to families. Emerging genotype-phenotype correlations should provide guidance for better medical care of individuals with tuberous sclerosis complex.
Collapse
Affiliation(s)
- Kit-Sing Au
- Department of Pediatrics, Division of Medical Genetics, The University of Texas Medical School at Houston, Houston, TX 77030, USA
| | | | | | | |
Collapse
|