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Agrawal M, Welshhans K. Local Translation Across Neural Development: A Focus on Radial Glial Cells, Axons, and Synaptogenesis. Front Mol Neurosci 2021; 14:717170. [PMID: 34434089 PMCID: PMC8380849 DOI: 10.3389/fnmol.2021.717170] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2021] [Accepted: 07/20/2021] [Indexed: 11/13/2022] Open
Abstract
In the past two decades, significant progress has been made in our understanding of mRNA localization and translation at distal sites in axons and dendrites. The existing literature shows that local translation is regulated in a temporally and spatially restricted manner and is critical throughout embryonic and post-embryonic life. Here, recent key findings about mRNA localization and local translation across the various stages of neural development, including neurogenesis, axon development, and synaptogenesis, are reviewed. In the early stages of development, mRNAs are localized and locally translated in the endfeet of radial glial cells, but much is still unexplored about their functional significance. Recent in vitro and in vivo studies have provided new information about the specific mechanisms regulating local translation during axon development, including growth cone guidance and axon branching. Later in development, localization and translation of mRNAs help mediate the major structural and functional changes that occur in the axon during synaptogenesis. Clinically, changes in local translation across all stages of neural development have important implications for understanding the etiology of several neurological disorders. Herein, local translation and mechanisms regulating this process across developmental stages are compared and discussed in the context of function and dysfunction.
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Affiliation(s)
- Manasi Agrawal
- School of Biomedical Sciences, Kent State University, Kent, OH, United States
| | - Kristy Welshhans
- Department of Biological Sciences, University of South Carolina, Columbia, SC, United States
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Cruz-Correa MR, Sala AC, Cintrón B, Hernández J, Olivera M, Cora A, Moore CM, Luciano CA, Soto-Salgado M, Giardiello FM, Hooper SR. Ubiquitous neurocognitive dysfunction in familial adenomatous polyposis: proof-of-concept of the role of APC protein in neurocognitive function. Hered Cancer Clin Pract 2020; 18:4. [PMID: 32123549 PMCID: PMC7041079 DOI: 10.1186/s13053-020-0135-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Accepted: 01/26/2020] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Familial adenomatous polyposis (FAP) is an autosomal dominant disorder caused by germline mutations in the APC gene. Patients with FAP have multiple extraintestinal manifestations that follow a genotype-phenotype pattern; however, few data exist characterizing their cognitive abilities. Given the role of the APC protein in development of the central nervous system, we hypothesized that patients with FAP would show differences in cognitive functioning compared to controls. METHODS Matched case-control study designed to evaluate cognitive function using the Test of Nonverbal Intelligence-4, the Bateria III Woodcock-Munoz, and the Behavior Rating Inventory of Executive Functions-Adult. Twenty-six individuals with FAP (mean age = 34.2 ± 15.0 years) and 25 age-gender and educational level matched controls (mean age = 32.7 ± 13.8 years) were evaluated. RESULTS FAP-cases had significantly lower IQ (p = 0.005). Across all tasks of the Batería III Woodcock-Muñoz, FAP-cases performed significantly lower than controls, with all of the summary scores falling in the bottom quartile compared to controls (p < 0.0001). Patients with FAP scored within the deficient range for Long-Term Retrieval and Cognitive Fluency. CONCLUSION APC protein has an important role in neurocognitive function. The pervasive nature of the observed cognitive dysfunction suggests that loss or dysfunction of the APC protein impacts processes in cortical and subcortical brain regions. Additional studies examining larger ethnically diverse cohorts with FAP are warranted.
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Affiliation(s)
- Marcia Roxana Cruz-Correa
- Department of Medicine, University of Puerto Rico School of Medicine, UPR Medical Sciences Campus, PO BOX 365067, San Juan, 00936 Puerto Rico
- Department of Biochemistry, University of Puerto Rico School of Medicine, San Juan, Puerto Rico
- Division of Cancer Biology, University of Puerto Rico Comprehensive Cancer Center, San Juan, Puerto Rico
- Division of Gastroenterology, School of Medicine, Johns Hopkins University, Baltimore, MD USA
| | - Ana Cecilia Sala
- Department of Medicine, University of Puerto Rico School of Medicine, UPR Medical Sciences Campus, PO BOX 365067, San Juan, 00936 Puerto Rico
| | - Beatriz Cintrón
- Department of Medicine, University of Puerto Rico School of Medicine, UPR Medical Sciences Campus, PO BOX 365067, San Juan, 00936 Puerto Rico
| | - Jessica Hernández
- Department of Medicine, University of Puerto Rico School of Medicine, UPR Medical Sciences Campus, PO BOX 365067, San Juan, 00936 Puerto Rico
| | - Myrta Olivera
- Department of Medicine, University of Puerto Rico School of Medicine, UPR Medical Sciences Campus, PO BOX 365067, San Juan, 00936 Puerto Rico
| | - Adrian Cora
- Department of Medicine, University of Puerto Rico School of Medicine, UPR Medical Sciences Campus, PO BOX 365067, San Juan, 00936 Puerto Rico
| | | | - Carlos A. Luciano
- Department of Medicine, Neurology Section, University of Puerto Rico School of Medicine, San Juan, Puerto Rico
| | - Marievelisse Soto-Salgado
- Department of Medicine, University of Puerto Rico School of Medicine, UPR Medical Sciences Campus, PO BOX 365067, San Juan, 00936 Puerto Rico
| | - Francis M. Giardiello
- Division of Gastroenterology, School of Medicine, Johns Hopkins University, Baltimore, MD USA
| | - Stephen R. Hooper
- Department of Allied Health Sciences, School of Medicine, University of North Carolina-Chapel Hill, Chapel Hill, NC USA
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Samadder NJ, Baffy N, Giridhar KV, Couch FJ, Riegert-Johnson D. Hereditary Cancer Syndromes-A Primer on Diagnosis and Management, Part 2: Gastrointestinal Cancer Syndromes. Mayo Clin Proc 2019; 94:1099-1116. [PMID: 31171120 DOI: 10.1016/j.mayocp.2019.01.042] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Accepted: 01/15/2019] [Indexed: 12/16/2022]
Abstract
Hereditary causes due to mutations and defects in certain genes account for roughly 5% to 10% of all colorectal cancers. These inherited syndromes have been associated with a 60% to 100% lifetime risk for development of colorectal cancer, depending on the genetic syndrome, and many also carry an increased risk for multiple extracolonic malignancies. In this second part of a review series on hereditary cancer syndromes, the focus will be to provide guidance on the features and management of the most commonly encountered hereditary colorectal cancers and polyposis conditions including Lynch syndrome, familial adenomatous polyposis, MUTYH-associated polyposis, and hamartomatous polyposis.
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Affiliation(s)
- N Jewel Samadder
- Division of Gastroenterology and Hepatology, Mayo Clinic, Scottsdale, AZ.
| | - Noemi Baffy
- Division of Gastroenterology and Hepatology, Mayo Clinic, Scottsdale, AZ
| | | | - Fergus J Couch
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN
| | - Douglas Riegert-Johnson
- Department of Clinical Genomics and Division of Gastroenterology and Hepatology, Mayo Clinic, Jacksonville, FL
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Talukdar S, Hawkes L, Hanson H, Kulkarni A, Brady AF, McMullan DJ, Ahn JW, Woodward E, Turnbull C. Structural Aberrations with Secondary Implications (SASIs): consensus recommendations for reporting of cancer susceptibility genes identified during analysis of Copy Number Variants (CNVs). J Med Genet 2019; 56:718-726. [DOI: 10.1136/jmedgenet-2018-105820] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Revised: 02/19/2019] [Accepted: 03/02/2019] [Indexed: 11/04/2022]
Abstract
Clinical testing with chromosomal microarray (CMA) is most commonly undertaken for clinical indications such as intellectual disability, dysmorphic features and/or congenital abnormalities. Identification of a structural aberration (SA) involving a cancer susceptibility gene (CSG) constitutes a type of incidental or secondary finding. Laboratory reporting, risk communication and clinical management of these structural aberrations with secondary implications (SASIs) is currently inconsistent. We undertake meta-analysis of 18 622 instances of CMA performed for unrelated indications in which 106 SASIs are identified involving in total 40 different CSGs. Here we present the recommendations of a joint UK working group representing the British Society of Genomic Medicine, UK Cancer Genetics Group and UK Association for Clinical Genomic Science. SASIs are categorised into four groups, defined by the type of SA and the cancer risk. For each group, recommendations are provided regarding reflex parental testing and cancer risk management.
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Kadiyska T, Tourtourikov I, Petrov A, Chavoushian A, Antalavicheva M, König EM, Klopocki E, Vessela N, Stanislavov R. Interstitial Deletion of 5q22.2q23.1 Including APC and TSSK1B in a Patient with Adenomatous Polyposis and Asthenoteratozoospermia. Mol Syndromol 2019; 9:235-240. [PMID: 30733657 DOI: 10.1159/000492516] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/17/2018] [Indexed: 11/19/2022] Open
Abstract
Interstitial 5q22 deletions are relatively rare and usually represented by severe clinical features such as developmental delay and growth retardation. Here, we report a 23-year-old male patient, referred to our laboratory for genetic confirmation of possible familial adenomatous polyposis. MLPA and the subsequent array CGH identified an approximately 8-Mb-sized deletion in the 5q22.2q23.1 locus. Further analysis of the deleted region and the genes within suggested a possible role for the TSSK1B (testis-specific serine/threonine kinase 1) gene in the patient's reproductive capacity. Semen analysis confirmed that the patient's reproductive capability was impaired, and that he suffered from asthenoteratozoospermia. Analysis of the azoospermia factor region on the Y chromosome revealed no microdeletions. Further sequencing tests could not find an alternative explanation for the patient's infertility. This case demonstrates a possible role of TSSK1B in male reproduction.
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Affiliation(s)
- Tanya Kadiyska
- Genetic Medico-Diagnostic Laboratory Genica, City Clinic Cancer Center, Sofia Medical University, Sofia, Bulgaria.,Department of Medical Chemistry and Biochemistry, Sofia Medical University, Sofia, Bulgaria
| | - Ivan Tourtourikov
- Genetic Medico-Diagnostic Laboratory Genica, City Clinic Cancer Center, Sofia Medical University, Sofia, Bulgaria
| | - Asen Petrov
- Department of Gastroenterology, City Clinic Cancer Center, Sofia Medical University, Sofia, Bulgaria
| | - Ani Chavoushian
- Department of Gastroenterology, City Clinic Cancer Center, Sofia Medical University, Sofia, Bulgaria
| | - Miglena Antalavicheva
- Department of Gastroenterology, City Clinic Cancer Center, Sofia Medical University, Sofia, Bulgaria
| | - Eva-Maria König
- Institute of Human Genetics, Biozentrum, University of Würzburg, Würzburg, Germany
| | - Eva Klopocki
- Institute of Human Genetics, Biozentrum, University of Würzburg, Würzburg, Germany
| | - Nikolova Vessela
- Genetic Medico-Diagnostic Laboratory Genica, City Clinic Cancer Center, Sofia Medical University, Sofia, Bulgaria
| | - Romil Stanislavov
- Genetic Medico-Diagnostic Laboratory Genica, City Clinic Cancer Center, Sofia Medical University, Sofia, Bulgaria
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Pirone A, Alexander J, Lau LA, Hampton D, Zayachkivsky A, Yee A, Yee A, Jacob MH, Dulla CG. APC conditional knock-out mouse is a model of infantile spasms with elevated neuronal β-catenin levels, neonatal spasms, and chronic seizures. Neurobiol Dis 2016; 98:149-157. [PMID: 27852007 DOI: 10.1016/j.nbd.2016.11.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Revised: 10/24/2016] [Accepted: 11/11/2016] [Indexed: 01/08/2023] Open
Abstract
Infantile spasms (IS) are a catastrophic childhood epilepsy syndrome characterized by flexion-extension spasms during infancy that progress to chronic seizures and cognitive deficits in later life. The molecular causes of IS are poorly defined. Genetic screens of individuals with IS have identified multiple risk genes, several of which are predicted to alter β-catenin pathways. However, evidence linking malfunction of β-catenin pathways and IS is lacking. Here, we show that conditional deletion in mice of the adenomatous polyposis coli gene (APC cKO), the major negative regulator of β-catenin, leads to excessive β-catenin levels and multiple salient features of human IS. Compared with wild-type littermates, neonatal APC cKO mice exhibit flexion-extension motor spasms and abnormal high-amplitude electroencephalographic discharges. Additionally, the frequency of excitatory postsynaptic currents is increased in layer V pyramidal cells, the major output neurons of the cerebral cortex. At adult ages, APC cKOs display spontaneous electroclinical seizures. These data provide the first evidence that malfunctions of APC/β-catenin pathways cause pathophysiological changes consistent with IS. Our findings demonstrate that the APC cKO is a new genetic model of IS, provide novel insights into molecular and functional alterations that can lead to IS, and suggest novel targets for therapeutic intervention.
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Affiliation(s)
- Antonella Pirone
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA 02111, United States
| | - Jonathan Alexander
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA 02111, United States; Neuroscience Program, Tufts Sackler School of Biomedical Sciences, Boston, MA 02111, United States
| | - Lauren A Lau
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA 02111, United States; Neuroscience Program, Tufts Sackler School of Biomedical Sciences, Boston, MA 02111, United States
| | - David Hampton
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA 02111, United States
| | - Andrew Zayachkivsky
- Department of Neurosurgery, Yale University School of Medicine, New Haven, CT 06520, United States
| | - Amy Yee
- Department of Developmental, Molecular, and Chemical Biology, Tufts University School of Medicine, Boston, MA 02111, United States
| | - Audrey Yee
- VA Eastern Colorado Health System, Golden, CO 80401, United States
| | - Michele H Jacob
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA 02111, United States.
| | - Chris G Dulla
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA 02111, United States.
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Differences in neuropsychological and behavioral parameters and brain structure in patients with familial adenomatous polyposis: a sibling-paired study. Hered Cancer Clin Pract 2016; 14:20. [PMID: 27777639 PMCID: PMC5057475 DOI: 10.1186/s13053-016-0060-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 10/01/2016] [Indexed: 11/13/2022] Open
Abstract
Background Familial adenomatous polyposis (FAP) is an autosomal dominant hereditary colon cancer syndrome caused by mutations in adenomatous polyposis coli (APC) with both colonic and extra-colonic manifestations. Case reports have noted an association with FAP and intellectual disability and animal studies have shown that APC is implicated in neural development and function, but no studies have investigated neuropsychological, behavioral, or structural brain characteristics of patients with FAP. Methods We undertook a pilot, sibling-pair study comparing three patients with FAP to their sex-matched siblings without FAP. Each sibling pair underwent neuropsychological testing by a blinded examiner, high resolution brain MRI scans, and the mother of each pair rated her children’s adaptive life skills and behavioral and emotional characteristics. Given the small number of study participants in this pilot study, quantitative comparisons of results were made by subtracting the score of the non-FAP sibling from the FAP patient on the various neuropsychological tests and parent rating questionnaires to calculate a difference, which was then divided by the standard deviation for each individual test to determine the difference, corrected for the standard deviation. Diffusion numbers in multiple regions of the brain as assessed by MRI were calculated for each study participant. Results We found similarity between siblings in all three pairs on a wide range of neuropsychological measures (general intelligence, executive function, and basic academic skills) as tested by the psychologist as well as in descriptions of adaptive life skills as rated by mothers. However, mothers’ ratings of behavioral and emotional characteristics of two of the three pairs showed differences between the siblings, specifically that the patients with FAP were found to have more behavioral and emotional problems compared to their siblings. No differences in brain structure were identified by MRI. Conclusion We report the first study exploring neuropsychological, behavioral, emotional, and structural brain characteristics of patients with FAP and found subjective differences as assessed by maternal perception in behavioral and emotional characteristics in patients with FAP compared to their siblings. Larger studies are needed to elucidate the relationship, if any, between FAP and brain function.
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Rosenfeld JA, Patel A. Chromosomal Microarrays: Understanding Genetics of Neurodevelopmental Disorders and Congenital Anomalies. J Pediatr Genet 2016; 6:42-50. [PMID: 28180026 DOI: 10.1055/s-0036-1584306] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Accepted: 04/23/2016] [Indexed: 01/09/2023]
Abstract
Chromosomal microarray (CMA) testing, used to identify DNA copy number variations (CNVs), has helped advance knowledge about genetics of human neurodevelopmental disease and congenital anomalies. It has aided in discovering new CNV syndromes and uncovering disease genes. It has discovered CNVs that are not fully penetrant and/or cause a spectrum of phenotypes, including intellectual disability, autism, schizophrenia, and dysmorphisms. Such CNVs can pose challenges to genetic counseling. They also have helped increase knowledge of genetic risk factors for neurodevelopmental disease and raised awareness of possible shared etiologies among these variable phenotypes. Advances in CMA technology allow CNV identification at increasingly finer scales, improving detection of pathogenic changes, although these sometimes are difficult to distinguish from normal population variation. This paper confronts some of the challenges uncovered by CMA testing while reviewing advances in genetics and the clinical use of this test that has replaced standard karyotyping in most genetic evaluations.
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Affiliation(s)
- Jill A Rosenfeld
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States; Baylor Miraca Genetics Laboratories, Baylor College of Medicine, Houston, Texas, United States
| | - Ankita Patel
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States; Baylor Miraca Genetics Laboratories, Baylor College of Medicine, Houston, Texas, United States
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Chrobak AA, Soltys Z. Bergmann Glia, Long-Term Depression, and Autism Spectrum Disorder. Mol Neurobiol 2016; 54:1156-1166. [PMID: 26809583 PMCID: PMC5310553 DOI: 10.1007/s12035-016-9719-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 01/12/2016] [Indexed: 12/22/2022]
Abstract
Bergmann glia (BG), a specific type of radial astrocytes in the cerebellum, play a variety of vital functions in the development of this structure. However, the possible role of BG in the development of abnormalities observed in individuals with autism spectrum disorder (ASD) seems to be underestimated. One of the most consistent findings observed in ASD patients is loss of Purkinje cells (PCs). Such a defect may be caused by dysregulation of glutamate homeostasis, which is maintained mainly by BG. Moreover, these glial cells are involved in long-term depression (LTD), a form of plasticity which can additionally subserve neuroprotective functions. The aim of presented review is to summarize the current knowledge about interactions which occur between PC and BG, with special emphasis on those which are relevant to the survival and proper functioning of cerebellar neurons.
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Affiliation(s)
- Adrian Andrzej Chrobak
- Department of Neuroanatomy, Institute of Zoology, Jagiellonian University, Gronostajowa St. 9, Cracow, 30-387, Poland. .,Faculty of Medicine, Jagiellonian University Medical College, Kopernika St. 21A, Cracow, 31-501, Poland.
| | - Zbigniew Soltys
- Department of Neuroanatomy, Institute of Zoology, Jagiellonian University, Gronostajowa St. 9, Cracow, 30-387, Poland
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Sahnane N, Bernasconi B, Carnevali I, Furlan D, Viel A, Sessa F, Tibiletti MG. Disruption of the APC gene by t(5;7) translocation in a Turcot family. Cancer Genet 2015; 209:107-11. [PMID: 26797314 DOI: 10.1016/j.cancergen.2015.12.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Revised: 12/04/2015] [Accepted: 12/09/2015] [Indexed: 01/12/2023]
Abstract
Turcot syndrome (TS) refers to the combination of colorectal polyps and primary tumours of the central nervous system. TS is a heterogeneous genetic condition due to APC and/or mismatch repair germline mutations. When APC is involved the vast majority of mutations are truncating, but in approximately 20%-30% of patients with familial polyposis no germline mutation can be found. A 30-year-old Caucasian woman with a positive pedigree for TS was referred to our Genetic Counselling Service. She was negative for APC and MUTYH but showed a reciprocal balanced translocation t(5;7)(q22;p15) at chromosome analysis. FISH analysis using specific BAC probes demonstrated that 5q22 breakpoint disrupted the APC gene. Transcript analysis by MLPA and digital PCR revealed that the cytogenetic rearrangement involving the 3' end of the APC gene caused a defective expression of a truncated transcript. This result allowed cytogenetic analysis to be offered to all the other family members and segregation analysis clearly demonstrated that all the carriers were affected, whereas non-carriers did not have the polyposis. A cytogenetic approach permitted the identification of the mutation-causing disease in this family, and the segregation analysis together with the transcript study supported the pathogenetic role of this mutation. Karyotype analysis was used as a predictive test in all members of this family. This family suggests that clinically positive TS and FAP cases, which test negative with standard molecular analysis, could be easily and cost-effectively resolved by a classical and molecular cytogenetic approach.
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Affiliation(s)
- Nora Sahnane
- Department of Surgical and Morphological Sciences, University of Insubria, via O. Rossi 9, IT-21100 Varese, Italy.
| | - Barbara Bernasconi
- Department of Surgical and Morphological Sciences, University of Insubria, via O. Rossi 9, IT-21100 Varese, Italy
| | - Ileana Carnevali
- Ospedale di Circolo di Varese, Unit of Pathology, via O. Rossi 9, IT-21100 Varese, Italy
| | - Daniela Furlan
- Department of Surgical and Morphological Sciences, University of Insubria, via O. Rossi 9, IT-21100 Varese, Italy
| | - Alessandra Viel
- CRO Aviano National Cancer Institute, Unit of Experimental Oncology 1, via F. Gallini 2, IT-33081 Aviano, PN, Italy
| | - Fausto Sessa
- Department of Surgical and Morphological Sciences, University of Insubria, via O. Rossi 9, IT-21100 Varese, Italy
| | - Maria Grazia Tibiletti
- Ospedale di Circolo di Varese, Unit of Pathology, via O. Rossi 9, IT-21100 Varese, Italy
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Adenomatous Polyposis Coli Protein Deletion in Efferent Olivocochlear Neurons Perturbs Afferent Synaptic Maturation and Reduces the Dynamic Range of Hearing. J Neurosci 2015; 35:9236-45. [PMID: 26085645 DOI: 10.1523/jneurosci.4384-14.2015] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
UNLABELLED Normal hearing requires proper differentiation of afferent ribbon synapses between inner hair cells (IHCs) and spiral ganglion neurons (SGNs) that carry acoustic information to the brain. Within individual IHCs, presynaptic ribbons show a size gradient with larger ribbons on the modiolar face and smaller ribbons on the pillar face. This structural gradient is associated with a gradient of spontaneous rates and threshold sensitivity, which is essential for a wide dynamic range of hearing. Despite their importance for hearing, mechanisms that direct ribbon differentiation are poorly defined. We recently identified adenomatous polyposis coli protein (APC) as a key regulator of interneuronal synapse maturation. Here, we show that APC is required for ribbon size heterogeneity and normal cochlear function. Compared with wild-type littermates, APC conditional knock-out (cKO) mice exhibit decreased auditory brainstem responses. The IHC ribbon size gradient is also perturbed. Whereas the normal-developing IHCs display ribbon size gradients before hearing onset, ribbon sizes are aberrant in APC cKOs from neonatal ages on. Reporter expression studies show that the CaMKII-Cre used to delete the floxed APC gene is present in efferent olivocochlear (OC) neurons, not IHCs or SGNs. APC loss led to increased volumes and numbers of OC inhibitory dopaminergic boutons on neonatal SGN fibers. Our findings identify APC in efferent OC neurons as essential for regulating ribbon heterogeneity, dopaminergic terminal differentiation, and cochlear sensitivity. This APC effect on auditory epithelial cell synapses resembles interneuronal and nerve-muscle synapses, thereby defining a global role for APC in synaptic maturation in diverse cell types. SIGNIFICANCE STATEMENT This study identifies novel molecules and cellular interactions that are essential for the proper maturation of afferent ribbon synapses in sensory cells of the inner ear, and for normal hearing.
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Adenomatous polyposis coli protein deletion leads to cognitive and autism-like disabilities. Mol Psychiatry 2014; 19:1133-42. [PMID: 24934177 PMCID: PMC4317257 DOI: 10.1038/mp.2014.61] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Revised: 04/16/2014] [Accepted: 04/25/2014] [Indexed: 12/14/2022]
Abstract
Intellectual disabilities (IDs) and autism spectrum disorders link to human APC inactivating gene mutations. However, little is known about adenomatous polyposis coli's (APC's) role in the mammalian brain. This study is the first direct test of the impact of APC loss on central synapses, cognition and behavior. Using our newly generated APC conditional knock-out (cKO) mouse, we show that deletion of this single gene in forebrain neurons leads to a multisyndromic neurodevelopmental disorder. APC cKO mice, compared with wild-type littermates, exhibit learning and memory impairments, and autistic-like behaviors (increased repetitive behaviors, reduced social interest). To begin to elucidate neuronal changes caused by APC loss, we focused on the hippocampus, a key brain region for cognitive function. APC cKO mice display increased synaptic spine density, and altered synaptic function (increased frequency of miniature excitatory synaptic currents, modestly enhanced long-term potentiation). In addition, we found excessive β-catenin levels and associated changes in canonical Wnt target gene expression and N-cadherin synaptic adhesion complexes, including reduced levels of presenilin1. Our findings identify some novel functional and molecular changes not observed previously in other genetic mutant mouse models of co-morbid cognitive and autistic-like disabilities. This work thereby has important implications for potential therapeutic targets and the impact of their modulation. We provide new insights into molecular perturbations and cell types that are relevant to human ID and autism. In addition, our data elucidate a novel role for APC in the mammalian brain as a hub that links to and regulates synaptic adhesion and signal transduction pathways critical for normal cognition and behavior.
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Valle L. Genetic predisposition to colorectal cancer: Where we stand and future perspectives. World J Gastroenterol 2014; 20:9828-9849. [PMID: 25110415 PMCID: PMC4123366 DOI: 10.3748/wjg.v20.i29.9828] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2013] [Revised: 02/10/2014] [Accepted: 04/03/2014] [Indexed: 02/06/2023] Open
Abstract
The development of colorectal cancer (CRC) can be influenced by genetic factors in both familial cases and sporadic cases. Familial CRC has been associated with genetic changes in high-, moderate- and low-penetrance susceptibility genes. However, despite the availability of current gene-identification techniques, the genetic causes of a considerable proportion of hereditary cases remain unknown. Genome-wide association studies of CRC have identified a number of common low-penetrance alleles associated with a slightly increased or decreased risk of CRC. The accumulation of low-risk variants may partly explain the familial risk of CRC, and some of these variants may modify the risk of cancer in patients with mutations in high-penetrance genes. Understanding the predisposition to develop CRC will require investigators to address the following challenges: the identification of genes that cause uncharacterized hereditary cases of CRC such as familial CRC type X and serrated polyposis; the classification of variants of unknown significance in known CRC-predisposing genes; and the identification of additional cancer risk modifiers that can be used to perform risk assessments for individual mutation carriers. We performed a comprehensive review of the genetically characterized and uncharacterized hereditary CRC syndromes and of low- and moderate-penetrance loci and variants identified through genome-wide association studies and candidate-gene approaches. Current challenges and future perspectives in the field of CRC predisposition are also discussed.
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Fancy SPJ, Harrington EP, Baranzini SE, Silbereis JC, Shiow LR, Yuen TJ, Huang EJ, Lomvardas S, Rowitch DH. Parallel states of pathological Wnt signaling in neonatal brain injury and colon cancer. Nat Neurosci 2014; 17:506-12. [PMID: 24609463 PMCID: PMC3975168 DOI: 10.1038/nn.3676] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2013] [Accepted: 02/13/2014] [Indexed: 02/07/2023]
Abstract
In colon cancer, mutation of the Wnt repressor Adenomatous polyposis coli (APC) leads to a state of aberrant and unrestricted “high-activity” signaling. However, relevance of high Wnt tone in non-genetic human disease is unknown. Here we demonstrate that distinct Wnt activity functional states determine oligodendrocyte precursor (OPC) differentiation and myelination. Murine OPCs with genetic Wnt dysregulation (high tone) express multiple genes in common with colon cancer including Lef1, SP5, Ets2, Rnf43 and Dusp4. Surprisingly, we find that OPCs in lesions of hypoxic human neonatal white matter injury upregulate markers of high Wnt activity and lack expression of APC. Finally, we show lack of Wnt repressor tone promotes permanent white matter injury after mild hypoxic insult. These findings suggest a state of pathological high-activity Wnt signaling in human disease tissues that lack pre-disposing genetic mutation.
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Affiliation(s)
- Stephen P J Fancy
- 1] Department of Pediatrics, University of California, San Francisco (UCSF), San Francisco, California, USA. [2] Department of Neurology, UCSF, San Francisco, California, USA. [3] Eli and Edythe Broad Institute for Stem Cell Research and Regeneration Medicine and Howard Hughes Medical Institute, UCSF, San Francisco, California, USA. [4]
| | - Emily P Harrington
- 1] Department of Pediatrics, University of California, San Francisco (UCSF), San Francisco, California, USA. [2] Eli and Edythe Broad Institute for Stem Cell Research and Regeneration Medicine and Howard Hughes Medical Institute, UCSF, San Francisco, California, USA. [3] Medical Scientist Training Program, UCSF, San Francisco, California, USA. [4]
| | | | - John C Silbereis
- 1] Department of Pediatrics, University of California, San Francisco (UCSF), San Francisco, California, USA. [2] Eli and Edythe Broad Institute for Stem Cell Research and Regeneration Medicine and Howard Hughes Medical Institute, UCSF, San Francisco, California, USA
| | - Lawrence R Shiow
- 1] Department of Pediatrics, University of California, San Francisco (UCSF), San Francisco, California, USA. [2] Eli and Edythe Broad Institute for Stem Cell Research and Regeneration Medicine and Howard Hughes Medical Institute, UCSF, San Francisco, California, USA
| | - Tracy J Yuen
- 1] Department of Pediatrics, University of California, San Francisco (UCSF), San Francisco, California, USA. [2] Eli and Edythe Broad Institute for Stem Cell Research and Regeneration Medicine and Howard Hughes Medical Institute, UCSF, San Francisco, California, USA
| | - Eric J Huang
- Department of Pathology, UCSF, San Francisco, California, USA
| | | | - David H Rowitch
- 1] Department of Pediatrics, University of California, San Francisco (UCSF), San Francisco, California, USA. [2] Eli and Edythe Broad Institute for Stem Cell Research and Regeneration Medicine and Howard Hughes Medical Institute, UCSF, San Francisco, California, USA
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15
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16
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Bruwer Z, Algar U, Vorster A, Fieggen K, Davidson A, Goldberg P, Wainwright H, Ramesar R. Predictive genetic testing in children: constitutional mismatch repair deficiency cancer predisposing syndrome. J Genet Couns 2013; 23:147-55. [PMID: 24122200 DOI: 10.1007/s10897-013-9659-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2013] [Accepted: 09/11/2013] [Indexed: 01/26/2023]
Abstract
Biallelic germline mutations in mismatch repair genes predispose to constitutional mismatch repair deficiency syndrome (CMMR-D). The condition is characterized by a broad spectrum of early-onset tumors, including hematological, brain and bowel and is frequently associated with features of Neurofibromatosis type 1. Few definitive screening recommendations have been suggested and no published reports have described predictive testing. We report on the first case of predictive testing for CMMR-D following the identification of two non-consanguineous parents, with the same heterozygous mutation in MLH1: c.1528C > T. The genetic counseling offered to the family, for their two at-risk daughters, is discussed with a focus on the ethical considerations of testing children for known cancer-causing variants. The challenges that are encountered when reporting on heterozygosity in a child younger than 18 years (disclosure of carrier status and risk for Lynch syndrome), when discovered during testing for homozygosity, are addressed. In addition, the identification of CMMR-D in a three year old, and the recommended clinical surveillance that was proposed for this individual is discussed. Despite predictive testing and presymptomatic screening, the sudden death of the child with CMMR-D syndrome occurred 6 months after her last surveillance MRI. This report further highlights the difficulty of developing guidelines, as a result of the rarity of cases and diversity of presentation.
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Panaccione I, Napoletano F, Forte AM, Kotzalidis GD, Del Casale A, Rapinesi C, Brugnoli C, Serata D, Caccia F, Cuomo I, Ambrosi E, Simonetti A, Savoja V, De Chiara L, Danese E, Manfredi G, Janiri D, Motolese M, Nicoletti F, Girardi P, Sani G. Neurodevelopment in schizophrenia: the role of the wnt pathways. Curr Neuropharmacol 2013; 11:535-58. [PMID: 24403877 PMCID: PMC3763761 DOI: 10.2174/1570159x113119990037] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Revised: 03/28/2013] [Accepted: 05/12/2013] [Indexed: 02/06/2023] Open
Abstract
OBJECTIVES To review the role of Wnt pathways in the neurodevelopment of schizophrenia. METHODS SYSTEMATIC PUBMED SEARCH, USING AS KEYWORDS ALL THE TERMS RELATED TO THE WNT PATHWAYS AND CROSSING THEM WITH EACH OF THE FOLLOWING AREAS: normal neurodevelopment and physiology, neurodevelopmental theory of schizophrenia, schizophrenia, and antipsychotic drug action. RESULTS Neurodevelopmental, behavioural, genetic, and psychopharmacological data point to the possible involvement of Wnt systems, especially the canonical pathway, in the pathophysiology of schizophrenia and in the mechanism of antipsychotic drug action. The molecules most consistently found to be associated with abnormalities or in antipsychotic drug action are Akt1, glycogen synthase kinase3beta, and beta-catenin. However, the extent to which they contribute to the pathophysiology of schizophrenia or to antipsychotic action remains to be established. CONCLUSIONS The study of the involvement of Wnt pathway abnormalities in schizophrenia may help in understanding this multifaceted clinical entity; the development of Wnt-related pharmacological targets must await the collection of more data.
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Affiliation(s)
- Isabella Panaccione
- NESMOS Department (Neuroscience, Mental Health, and Sensory Organs), Sapienza University, School of Medicine and Psychology, Sant’Andrea Hospital, Rome, Italy
| | - Flavia Napoletano
- NESMOS Department (Neuroscience, Mental Health, and Sensory Organs), Sapienza University, School of Medicine and Psychology, Sant’Andrea Hospital, Rome, Italy
| | - Alberto Maria Forte
- NESMOS Department (Neuroscience, Mental Health, and Sensory Organs), Sapienza University, School of Medicine and Psychology, Sant’Andrea Hospital, Rome, Italy
| | - Giorgio D. Kotzalidis
- NESMOS Department (Neuroscience, Mental Health, and Sensory Organs), Sapienza University, School of Medicine and Psychology, Sant’Andrea Hospital, Rome, Italy
| | - Antonio Del Casale
- NESMOS Department (Neuroscience, Mental Health, and Sensory Organs), Sapienza University, School of Medicine and Psychology, Sant’Andrea Hospital, Rome, Italy
| | - Chiara Rapinesi
- NESMOS Department (Neuroscience, Mental Health, and Sensory Organs), Sapienza University, School of Medicine and Psychology, Sant’Andrea Hospital, Rome, Italy
| | - Chiara Brugnoli
- NESMOS Department (Neuroscience, Mental Health, and Sensory Organs), Sapienza University, School of Medicine and Psychology, Sant’Andrea Hospital, Rome, Italy
| | - Daniele Serata
- NESMOS Department (Neuroscience, Mental Health, and Sensory Organs), Sapienza University, School of Medicine and Psychology, Sant’Andrea Hospital, Rome, Italy
| | - Federica Caccia
- NESMOS Department (Neuroscience, Mental Health, and Sensory Organs), Sapienza University, School of Medicine and Psychology, Sant’Andrea Hospital, Rome, Italy
| | - Ilaria Cuomo
- NESMOS Department (Neuroscience, Mental Health, and Sensory Organs), Sapienza University, School of Medicine and Psychology, Sant’Andrea Hospital, Rome, Italy
| | - Elisa Ambrosi
- NESMOS Department (Neuroscience, Mental Health, and Sensory Organs), Sapienza University, School of Medicine and Psychology, Sant’Andrea Hospital, Rome, Italy
| | - Alessio Simonetti
- NESMOS Department (Neuroscience, Mental Health, and Sensory Organs), Sapienza University, School of Medicine and Psychology, Sant’Andrea Hospital, Rome, Italy
| | - Valeria Savoja
- NESMOS Department (Neuroscience, Mental Health, and Sensory Organs), Sapienza University, School of Medicine and Psychology, Sant’Andrea Hospital, Rome, Italy
| | - Lavinia De Chiara
- NESMOS Department (Neuroscience, Mental Health, and Sensory Organs), Sapienza University, School of Medicine and Psychology, Sant’Andrea Hospital, Rome, Italy
| | - Emanuela Danese
- NESMOS Department (Neuroscience, Mental Health, and Sensory Organs), Sapienza University, School of Medicine and Psychology, Sant’Andrea Hospital, Rome, Italy
| | - Giovanni Manfredi
- NESMOS Department (Neuroscience, Mental Health, and Sensory Organs), Sapienza University, School of Medicine and Psychology, Sant’Andrea Hospital, Rome, Italy
| | - Delfina Janiri
- NESMOS Department (Neuroscience, Mental Health, and Sensory Organs), Sapienza University, School of Medicine and Psychology, Sant’Andrea Hospital, Rome, Italy
| | | | - Ferdinando Nicoletti
- NEUROMED, Pozzilli, Isernia, Italy
- Department of Neuropharmacology, Sapienza University, School of Medicine and Pharmacy, Rome, Italy
| | - Paolo Girardi
- NESMOS Department (Neuroscience, Mental Health, and Sensory Organs), Sapienza University, School of Medicine and Psychology, Sant’Andrea Hospital, Rome, Italy
- Centro Lucio Bini, Rome, Italy
| | - Gabriele Sani
- NESMOS Department (Neuroscience, Mental Health, and Sensory Organs), Sapienza University, School of Medicine and Psychology, Sant’Andrea Hospital, Rome, Italy
- Centro Lucio Bini, Rome, Italy
- IRCCS Santa Lucia Foundation, Department of Clinical and Behavioural Neurology, Neuropsychiatry Laboratory, Rome, Italy
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Lohn Z, Adam S, Birch PH, Friedman JM. Incidental findings from clinical genome-wide sequencing: a review. J Genet Couns 2013; 23:463-73. [PMID: 23709124 DOI: 10.1007/s10897-013-9604-4] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2012] [Accepted: 05/02/2013] [Indexed: 12/11/2022]
Abstract
There are several unresolved challenges associated with the clinical application of genome-wide sequencing technologies. One of the most discussed issues is incidental findings (IF), which are defined as discoveries made as a result of genetic testing that are unrelated to the indication for the test. The discussion surrounding IF began in the context of research, which we have used to frame consideration of IF in the clinical context. There is growing consensus that analytically valid and medically actionable IF should be offered to patients, but whether and to what extent clinicians should disclose other kinds of IF is debated. While others have systematically reviewed the literature concerning genetic IF, previous reviews focus on ethical and research-related issues and do not consider the implications for the genetic counseling profession specifically. This review discusses the practical considerations, ethical concerns and genetic counseling issues related to IF, with a particular focus on clinical genome-wide sequencing. To date, the bulk of the literature with respect to IF in the clinical context consists of commentaries, reviews and case reports. There is a need for more empirical studies to provide a foundation for institutional protocols and evidence-based clinical practice standards.
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Affiliation(s)
- Z Lohn
- Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada,
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Ellison JW, Ravnan JB, Rosenfeld JA, Morton SA, Neill NJ, Williams MS, Lewis J, Torchia BS, Walker C, Traylor RN, Moles K, Miller E, Lantz J, Valentin C, Minier SL, Leiser K, Powell BR, Wilks TM, Shaffer LG. Clinical utility of chromosomal microarray analysis. Pediatrics 2012; 130:e1085-95. [PMID: 23071206 DOI: 10.1542/peds.2012-0568] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
OBJECTIVE To test the hypothesis that chromosomal microarray analysis frequently diagnoses conditions that require specific medical follow-up and that referring physicians respond appropriately to abnormal test results. METHODS A total of 46,298 postnatal patients were tested by chromosomal microarray analysis for a variety of indications, most commonly intellectual disability/developmental delay, congenital anomalies, dysmorphic features, and neurobehavioral problems. The frequency of detection of abnormalities associated with actionable clinical features was tallied, and the rate of physician response to a subset of abnormal tests results was monitored. RESULTS A total of 2088 diagnoses were made of more than 100 different disorders that have specific clinical features that warrant follow-up. The detection rate for these conditions using high-resolution whole-genome microarrays was 5.4%, which translates to 35% of all clinically significant abnormal test results identified in our laboratory. In a subset of cases monitored for physician response, appropriate clinical action was taken more than 90% of the time as a direct result of the microarray finding. CONCLUSIONS The disorders diagnosed by chromosomal microarray analysis frequently have clinical features that need medical attention, and physicians respond to the diagnoses with specific clinical actions, thus arguing that microarray testing provides clinical utility for a significant number of patients tested.
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Affiliation(s)
- Jay W Ellison
- Signature Genomic Laboratories, PerkinElmer, Inc, Spokane, Washington 99207, USA.
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Hogan J, Turner A, Tucker K, Warwick L. Unintended diagnosis of Von Hippel Lindau syndrome using Array Comparative Genomic Hybridization (CGH): counseling challenges arising from unexpected information. J Genet Couns 2012; 22:22-6. [PMID: 22895882 DOI: 10.1007/s10897-012-9520-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2011] [Accepted: 06/14/2012] [Indexed: 01/08/2023]
Abstract
Array Comparative Genomic Hybridization (array CGH) is a powerful tool for identifying genomic imbalances and providing a diagnosis in individuals with a normal karyotype. It has been particularly useful in the investigation of individuals with developmental delay +/-, dysmorphic features and/or multiple congenital abnormalities. However, this non-targeted method of scanning the whole genome can reveal unexpected information. We present a case where array CGH identified the cause of a proband's moderate mental retardation by discovery of a de novo deletion of chromosome 3p25.3. This deletion was shown to contain at least 25 genes including the VHL gene, the deletion or mutation of which leads to Von Hippel Lindau (VHL) syndrome. Presymptomatic testing for VHL is usually offered after appropriate genetic counseling about the implications of this condition. Therefore, scanning the genome by array CGH presents a number of challenges for the genetic counselor. We suggest that further understanding of the psychosocial effects of array CGH is needed in order for appropriate pre- and post-test counseling to be provided.
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Affiliation(s)
- Jennifer Hogan
- ACT Genetic Service The Canberra Hospital, Canberra, ACT, Australia.
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21
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Impact of genotype-first diagnosis: the detection of microdeletion and microduplication syndromes with cancer predisposition by aCGH. Genet Med 2009; 11:314-22. [DOI: 10.1097/gim.0b013e3181a028a5] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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22
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Ivaniutsin U, Chen Y, Mason JO, Price DJ, Pratt T. Adenomatous polyposis coli is required for early events in the normal growth and differentiation of the developing cerebral cortex. Neural Dev 2009; 4:3. [PMID: 19149881 PMCID: PMC2649069 DOI: 10.1186/1749-8104-4-3] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2008] [Accepted: 01/16/2009] [Indexed: 12/21/2022] Open
Abstract
Background Adenomatous polyposis coli (Apc) is a large multifunctional protein known to be important for Wnt/β-catenin signalling, cytoskeletal dynamics, and cell polarity. In the developing cerebral cortex, Apc is expressed in proliferating cells and its expression increases as cells migrate to the cortical plate. We examined the consequences of loss of Apc function for the early development of the cerebral cortex. Results We used Emx1Cre to inactivate Apc specifically in proliferating cerebral cortical cells and their descendents starting from embryonic day 9.5. We observed reduction in the size of the mutant cerebral cortex, disruption to its organisation, and changes in the molecular identity of its cells. Loss of Apc leads to a decrease in the size of the proliferative pool, disrupted interkinetic nuclear migration, and increased apoptosis. β-Catenin, pericentrin, and N-cadherin proteins no longer adopt their normal high concentration at the apical surface of the cerebral cortical ventricular zone, indicating that cell polarity is disrupted. Consistent with enhanced Wnt/β-catenin signalling resulting from loss of Apc we found increased levels of TCF/LEF-dependent transcription and expression of endogenous Wnt/β-catenin target genes (Axin2 (conductin), Lef1, and c-myc) in the mutant cerebral cortex. In the Apc mutant cerebral cortex the expression of transcription factors Foxg1, Pax6, Tbr1, and Tbr2 is drastically reduced compared to normal and many cells ectopically express Pax3, Wnt1, and Wt1 (but not Wnt2b, Wnt8b, Ptc, Gli1, Mash1, Olig2, or Islet1). This indicates that loss of Apc function causes cerebral cortical cells to lose their normal identity and redirect to fates normally found in more posterior-dorsal regions of the central nervous system. Conclusion Apc is required for multiple aspects of early cerebral cortical development, including the regulation of cell number, interkinetic nuclear migration, cell polarity, and cell type specification.
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Affiliation(s)
- Uladzislau Ivaniutsin
- Genes and Development Group, Centre for Integrative Physiology, School of Biomedical Sciences, The University of Edinburgh, Edinburgh, UK.
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Abstract
The development of microarray-based comparative genomic hybridization (array CGH) methods represents a critical new advance in molecular cytogenetics. This new technology has driven a technical convergence between molecular diagnostics and clinical cytogenetics, questioned our naïve understanding of the complexity of the human genome, revolutionized the practice of medical genetics, challenged conventional wisdom related to the genetic bases of multifactorial and sporadic conditions, and is poised to impact all areas of medicine. The use of contemporary molecular cytogenetic techniques in research and diagnostics has resulted in the identification of many new syndromes, expanded our knowledge about the phenotypic spectrum of recognizable syndromes, elucidated the genomic bases of well-established clinical conditions, and refined our view about the molecular mechanisms of some chromosomal aberrations. Newer methodologies are being developed, which will likely lead to a new understanding of the genome and its relationship to health and disease.
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Affiliation(s)
- Bassem A Bejjani
- Signature Genomic Laboratories, LLC, Spokane, Washington 99202, USA.
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