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Green TE, MacGregor D, Carden SM, Harris RV, Hewitt CA, Berkovic SF, Penington AJ, Scheffer IE, Hildebrand MS. Identification of a recurrent mosaic KRAS variant in brain tissue from an individual with nevus sebaceous syndrome. Cold Spring Harb Mol Case Stud 2021; 7:mcs.a006133. [PMID: 34649968 PMCID: PMC8751419 DOI: 10.1101/mcs.a006133] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2021] [Accepted: 09/29/2021] [Indexed: 11/24/2022] Open
Abstract
Nevus sebaceous syndrome (NSS) is a rare, multisystem neurocutaneous disorder, characterized by a congenital nevus, and may include brain malformations such as hemimegalencephaly or focal cortical dysplasia, ocular, and skeletal features. It has been associated with several eponyms including Schimmelpenning and Jadassohn. The isolated skin lesion, nevus sebaceous, is associated with postzygotic variants in HRAS or KRAS in all individuals studied. The RAS proteins encode a family of GTPases that form part of the RAS/MAPK signaling pathway, which is critical for cell cycle regulation and differentiation during development. We studied an individual with nevus sebaceous syndrome with an extensive nevus sebaceous, epilepsy, intellectual disability, and hippocampal sclerosis without pathological evidence of a brain malformation. We used high-depth gene panel sequencing and droplet digital polymerase chain reaction (PCR) to detect and quantify RAS/MAPK gene variants in nevus sebaceous and temporal lobe tissue collected during plastic and epilepsy surgery, respectively. A mosaic KRAS c.34G > T; p.(Gly12Cys) variant, also known as G12C, was detected in nevus sebaceous tissue at 25% variant allele fraction (VAF), at the residue most commonly substituted in KRAS. Targeted droplet digital PCR validated the variant and quantified the mosaicism in other tissues. The variant was detected at 33% in temporal lobe tissue but was absent from blood and healthy skin. We provide molecular confirmation of the clinical diagnosis of NSS. Our data extends the histopathological spectrum of KRAS G12C mosaicism beyond nevus sebaceous to involve brain tissue and, more specifically, hippocampal sclerosis.
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Affiliation(s)
| | - Duncan MacGregor
- Anatomical Pathology, Royal Children's Hospital, Parkville, Victoria, Australia
| | - Susan M Carden
- Department of Ophthalmology, The Royal Children's Hospital, Parkville, Victoria, Australia; Department of Ophthalmology, The Royal Victorian Eye and Ear Hospital, East Melbourne, Victoria, Australia ; Department of Paediatrics, University of Melbourne,
| | - Rebekah V Harris
- Epilepsy Research Centre, Department of Medicine (Austin Hospital), University of Melbourne, Heidelberg, Victoria, Australia
| | - Chelsee A Hewitt
- Department of Pathology, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - Samuel F Berkovic
- Epilepsy Research Centre, Department of Medicine (Austin Hospital), University of Melbourne, Heidelberg, Victoria, Australia
| | - Anthony J Penington
- Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Murdoch Children's Research Institute ; Plastic and Maxillofacial Surgery Department, The Royal Children's Hospital
| | - Ingrid E Scheffer
- Epilepsy Research Centre, Department of Medicine (Austin Hospital), University of Melbourne, Heidelberg, Victoria, Australia ; Departments of Paediatrics and Neurology, Austin Health, Heidelberg, Victoria, Australia
| | - Michael S Hildebrand
- Epilepsy Research Centre, Department of Medicine (Austin Hospital), University of Melbourne, Heidelberg, Victoria, Australia; Murdoch Children Research Institute, Parkville, Victoria, Australia
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The Role of KRAS Mutations in Cortical Malformation and Epilepsy Surgery: A Novel Report of Nevus Sebaceous Syndrome and Review of the Literature. Brain Sci 2021; 11:brainsci11060793. [PMID: 34208656 PMCID: PMC8234150 DOI: 10.3390/brainsci11060793] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 05/27/2021] [Accepted: 06/11/2021] [Indexed: 12/12/2022] Open
Abstract
The rare nevus sebaceous (NS) syndrome (NSS) includes cortical malformations and drug-resistant epilepsy. Somatic RAS-pathway genetic variants are pathogenetic in NS, but not yet described within the brain of patients with NSS. We report on a 5-year-old boy with mild psychomotor delay. A brown-yellow linear skin lesion suggestive of NS in the left temporo-occipital area was evident at birth. Epileptic spasms presented at aged six months. EEG showed continuous left temporo-occipital epileptiform abnormalities. Brain MRI revealed a similarly located diffuse cortical malformation with temporal pole volume reduction and a small hippocampus. We performed a left temporo-occipital resection with histopathological diagnosis of focal cortical dysplasia type Ia in the occipital region and hippocampal sclerosis type 1. Three years after surgery, he is seizure-and drug-free (Engel class Ia) and showed cognitive improvement. Genetic examination of brain and skin specimens revealed the c.35G > T (p.Gly12Val) KRAS somatic missense mutation. Literature review suggests epilepsy surgery in patients with NSS is highly efficacious, with 73% probability of seizure freedom. The few histological analyses reported evidenced disorganized cortex, occasionally with cytomegalic neurons. This is the first reported association of a KRAS genetic variant with cortical malformations associated with epilepsy, and suggests a possible genetic substrate for hippocampal sclerosis.
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Gröppel G, von Oertzen TJ. Okzipitallappenepilepsie und Parietallappenepilepsie – eine Maskerade. ZEITSCHRIFT FÜR EPILEPTOLOGIE 2021; 34:93-97. [DOI: 10.1007/s10309-020-00383-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 12/02/2020] [Indexed: 08/30/2023]
Abstract
ZusammenfassungWir berichten über ein 7‑jähriges Mädchen mit therapierefraktärer Okzipitallappenepilepsie, welche zu Beginn als Migräne fehlinterpretiert wurde. In weiterer Folge diskutieren wir die klinische Semiologie, die Elektrophysiologie und die Bildgebung v. a. im Hinblick auf die Differenzialdiagnose zur Parietallappenepilepsie.
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De Vito A, Taranath A, Dahmoush H, Ganapathy SS, Sudhakar S, Mankad K. Neuroimaging manifestations of epidermal nevus syndrome. Quant Imaging Med Surg 2021; 11:415-422. [PMID: 33392041 DOI: 10.21037/qims-20-634] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Epidermal nevus syndrome (ENS) represents a diverse group of rare neurocutaneous diseases associated with the presence of characteristic epidermal nevi (EN) in the skin and extracutaneous manifestations in the eyes, skeletal, urogenital and central nervous systems. We present a case series of 7 children with ENS, with specific attention to the neuroradiological characteristics of this entity.
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Affiliation(s)
- Andrea De Vito
- Department of Neuroradiology, H. S. Gerardo Monza, Monza, Italy
| | - Ajay Taranath
- Department of Radiology, Women's and Children's Hospital, North Adelaide, South Australia, Australia
| | - Hisham Dahmoush
- Department of Radiology, Lucile Packard Children's Hospital, Stanford University School of Medicine, Stanford, CA, USA
| | | | - Sniya Sudhakar
- Department of Radiology, Great Ormond Street Hospital, London, UK
| | - Kshitij Mankad
- Department of Radiology, Great Ormond Street Hospital, London, UK
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Chacon‐Camacho OF, Lopez‐Moreno D, Morales‐Sanchez MA, Hofmann E, Pacheco‐Quito M, Wieland I, Cortes‐Gonzalez V, Villanueva‐Mendoza C, Zenker M, Zenteno JC. Expansion of the phenotypic spectrum and description of molecular findings in a cohort of patients with oculocutaneous mosaic RASopathies. Mol Genet Genomic Med 2019; 7:e625. [PMID: 30891959 PMCID: PMC6503218 DOI: 10.1002/mgg3.625] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 02/08/2019] [Accepted: 02/11/2019] [Indexed: 02/01/2023] Open
Abstract
BACKGROUND Postzygotic KRAS, HRAS, NRAS, and FGFR1 mutations result in a group of mosaic RASopathies characterized by related developmental anomalies in eye, skin, heart, and brain. These oculocutaneous disorders include oculoectodermal syndrome (OES) encephalo-cranio-cutaneous lipomatosis (ECCL), and Schimmelpenning-Feuerstein-Mims syndrome (SFMS). Here, we report the results of the clinical and molecular characterization of a novel cohort of patients with oculocutaneous mosaic RASopathies. METHODS Two OES, two ECCL, and two SFMS patients were ascertained in the study. In addition, two subjects with unilateral isolated epibulbar dermoids were also enrolled. Molecular analysis included PCR amplification and Sanger sequencing of KRAS, HRAS, NRAS, and FGFR1 genes in DNA obtained from biopsies (skin/epibulbar dermoids), buccal mucosa, and blood leukocytes. Massive parallel sequencing was employed in two cases with low-level mosaicism. RESULTS In DNA from biopsies, mosaicism for pathogenic variants, including KRAS p.Ala146Thr in two OES subjects, FGFR1 p.Asn546Lys and KRAS p.Ala146Val in ECCL patients, and KRAS p.Gly12Asp in both SFMS patients, was demonstrated. No mutations were shown in DNA from conjunctival lesions in two subjects with isolated epibubar dermoids. CONCLUSION Our study allowed the expansion of the clinical spectrum of mosaic RASopathies and supports that mosaicism for recurrent mutations in KRAS and FGFR1 is a commonly involved mechanism in these rare oculocutaneous anomalies.
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Affiliation(s)
| | - Daniel Lopez‐Moreno
- Department of GeneticsInstitute of Ophthalmology “Conde de Valenciana”Mexico CityMexico
| | | | - Enriqueta Hofmann
- Department of GlaucomaInstitute of Ophthalmology “Conde de Valenciana”Mexico CityMexico
| | | | - Ilse Wieland
- Institute of Human Genetics, University HospitalMagdeburgGermany
| | - Vianney Cortes‐Gonzalez
- Department of GeneticsHospital "Dr. Luis Sanchez Bulnes", Asociación para Evitar la Ceguera en MéxicoMexico CityMexico
| | - Cristina Villanueva‐Mendoza
- Department of GeneticsHospital "Dr. Luis Sanchez Bulnes", Asociación para Evitar la Ceguera en MéxicoMexico CityMexico
| | - Martin Zenker
- Institute of Human Genetics, University HospitalMagdeburgGermany
| | - Juan Carlos Zenteno
- Department of GeneticsInstitute of Ophthalmology “Conde de Valenciana”Mexico CityMexico
- Department of Biochemistry, Faculty of MedicineUNAMMexico CityMexico
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Kasinathan A, Padmanabh H, Gupta K, Sankhyan N, Singh P, Singhi P. Unusual Cause of West Syndrome. J Pediatr Neurosci 2017; 12:288-290. [PMID: 29204211 PMCID: PMC5696673 DOI: 10.4103/jpn.jpn_24_17] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Schimmelpenning-Feuerstein-Mims syndrome is a congenital neurocutaneous disorder, comprising of organoid epidermal nevus with a broad spectrum of multiorgan dysfunction (neurologic, skeletal, cardiovascular, ophthalmic, and urologic) secondary to postzygotic mutation in the early embryonic period. Predominant neurological manifestations include epilepsy, intellectual impairment, and focal deficits. Here, we report a 3-year-old girl who presented with epileptic spasms and had a characteristic linear sebaceous nevus. This report not only highlights the importance of early diagnosis of this condition but also emphasizes the need for multiorgan screening in children with seizures and nevi.
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Affiliation(s)
| | - Hansashree Padmanabh
- Department of Pediatrics, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Kirti Gupta
- Department of Pathology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Naveen Sankhyan
- Department of Pediatrics, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Paramjeet Singh
- Department of Radiodiagnosis, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Pratibha Singhi
- Department of Pediatrics, Postgraduate Institute of Medical Education and Research, Chandigarh, India
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Ullah W, Abdullah HMA, Shahzad MA, Sadiq MA, Ahmad E, Khan S. First Reported Case of 'Epidermal Nevus Syndrome' with a Triad of Central Nervous System Deformities. Cureus 2016; 8:e916. [PMID: 28083460 PMCID: PMC5218882 DOI: 10.7759/cureus.916] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Epidermal nevus syndrome (ENS) is a term used to describe the occurrence of an epidermal nevus in association with other extra-cutaneous developmental anomalies, most commonly involving the nervous and musculoskeletal systems. The nevus is classified on the basis of the main component which may be keratinocytic, sebaceous, follicular, apocrine, or eccrine. Most patients who present with ENS is at the time of birth, though some become apparent later in life. This case describes a young female who presented with seizures and cognitive impairment along with a linear epidermal nevus on the midline of her face. The presence of the nevus prompted brain imaging which showed cortical dysplasia, multiple hamartomas in the temporal lobe, thalamus, and periventricular regions along with cerebellar atrophy and Dandy-Walker variant. To our knowledge, this is the first case in which three different types of brain lesions were found in the same patient.
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Affiliation(s)
- Waqas Ullah
- Internal Medicine, University of Arizona, Tucson, AZ
| | | | | | | | - Ejaz Ahmad
- Internal Medicine, Nishtar Hospital, Multan, Pakistan
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Israni A, Dubey R, Chakrabarty B, Kumar A, Gulati S. Cutaneous and brain malformations of epidermal nevus syndrome: A classical image. J Pediatr Neurosci 2016; 11:285-286. [PMID: 27857810 PMCID: PMC5108144 DOI: 10.4103/1817-1745.193362] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Affiliation(s)
- Anil Israni
- Division of Child Neurology, Department of Pediatrics, All Institute of Medical Sciences, New Delhi, India
| | - Rachana Dubey
- Division of Child Neurology, Department of Pediatrics, All Institute of Medical Sciences, New Delhi, India
| | - Biswaroop Chakrabarty
- Division of Child Neurology, Department of Pediatrics, All Institute of Medical Sciences, New Delhi, India
| | - Atin Kumar
- Department of Radiodiagnosis, All Institute of Medical Sciences, New Delhi, India
| | - Sheffali Gulati
- Division of Child Neurology, Department of Pediatrics, All Institute of Medical Sciences, New Delhi, India
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Hammond CK, Shapson-Coe A, Govender R, van Toorn R, Ndondo A, Wieselthaler N, Eley B, Mubaiwa L, Wilmshurst JM. Moyamoya Syndrome in South African Children With HIV-1 Infection. J Child Neurol 2016; 31:1010-7. [PMID: 26961262 DOI: 10.1177/0883073816635747] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Accepted: 02/04/2016] [Indexed: 11/17/2022]
Abstract
A national multicenter study identified 17 South African children with vertically acquired HIV-1 infection and HIV-associated vasculopathy. Five of the children (all indigenous African ancestry) had progressive vascular disease, consistent with moyamoya syndrome. Median presentation age 5.8 years (range 2.2-11). The children with moyamoya syndrome presented with abnormal CD4 counts and raised viral loads. Clinical features included motor deficits, neuroregression, and intellectual disability. Neuroimaging supported progressive vascular disease with preceding clinically silent disease course. Neurologic recovery occurred in 1 patient with improved CD4 counts. Four of the 5 children presented during the era when access to antiretroviral therapy was limited, suggesting that with improved management of HIV-1, progressive vasculopathy is less prevalent. However the insidious disease course illustrated indicates that the syndrome can progress "silently," and manifest with misleading phenotypes such as cognitive delay or regression. Sub-Saharan Africa has limited access to neuroimaging and affected children may be underdiagnosed.
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Affiliation(s)
- Charles K Hammond
- Department of Paediatric Neurology, Department of Paediatrics and Child Health, Red Cross War Memorial Children's Hospital, University of Cape Town, Cape Town, South Africa
| | - Alexander Shapson-Coe
- Department of Paediatric Neurology, Department of Paediatrics and Child Health, Red Cross War Memorial Children's Hospital, University of Cape Town, Cape Town, South Africa
| | - Rajeshree Govender
- Department of Paediatric Neurology, University of Kwa-Zulu Natal, Inkosi Albert Luthuli Central Hospital, Durban, South Africa
| | - Ronald van Toorn
- Department of Paediatric Neurology, Department of Paediatrics and Child health, Stellenbosch University, Cape Town, South Africa
| | - Alvin Ndondo
- Department of Paediatric Neurology, Department of Paediatrics and Child Health, Red Cross War Memorial Children's Hospital, University of Cape Town, Cape Town, South Africa
| | - Nicky Wieselthaler
- Department Paediatric Radiology, Department of Paediatrics and Child Health, Red Cross War Memorial Children's Hospital, University of Cape Town, Cape Town, South Africa
| | - Brian Eley
- Paediatric Infectious Diseases Unit, Department of Paediatrics and Child Health, Red Cross War Memorial Children's Hospital, University of Cape Town, Cape Town, South Africa
| | - Lawrence Mubaiwa
- Department of Paediatric Neurology, University of Kwa-Zulu Natal, Inkosi Albert Luthuli Central Hospital, Durban, South Africa
| | - Jo M Wilmshurst
- Department of Paediatric Neurology, Department of Paediatrics and Child Health, Red Cross War Memorial Children's Hospital, University of Cape Town, Cape Town, South Africa
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Abstract
The term epidermal nevus syndrome (ENS) has been used to describe the association of epidermal hamartomas and extracutaneous abnormalities. Although many continue to use the term "ENS," it is now understood that this is not one disease, but rather a heterogeneous group with distinct genetic profiles defined by a common cutaneous phenotype: the presence of epidermal and adnexal hamartomas that are associated with other organ system involvement. One commonality is that epidermal nevi often follow the lines of Blaschko and it appears the more widespread the cutaneous manifestations, the greater the risk for extracutaneous manifestations. The majority of the extracutaneous manifestations involve the brain, eye, and skeletal systems. The CNS involvement is wide ranging and involves both clinical manifestations such as intellectual disability and seizures, as well as structural anomalies. Several subsets of ENS with characteristic features have been delineated including the nevus sebaceus syndrome, Proteus syndrome, CHILD syndrome, Becker's nevus syndrome, nevus comedonicus syndrome, and phakomatosis pigmentokeratotica. Advances in molecular biology have revealed that the manifestations of ENS are due to genomic mosaicism. It is likely that the varied clinical manifestations of ENS are due in great part to the functional effects of specific genetic defects. Optimal management of the patient with ENS involves an interdisciplinary approach given the potential for multisystem involvement. Of note, epidermal nevi have been associated with both benign and malignant neoplasms, and thus ongoing clinical follow-up is required.
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Affiliation(s)
- Sarah Asch
- Department of Dermatology, University of California San Francisco, San Francisco, CA, USA
| | - Jeffrey L Sugarman
- Departments of Dermatology and Community and Family Medicine, University of California San Francisco, Santa Rosa, CA, USA.
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Mirzaa GM, Poduri A. Megalencephaly and hemimegalencephaly: breakthroughs in molecular etiology. AMERICAN JOURNAL OF MEDICAL GENETICS PART C-SEMINARS IN MEDICAL GENETICS 2014; 166C:156-72. [PMID: 24888963 DOI: 10.1002/ajmg.c.31401] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Megalencephaly (MEG) is a developmental disorder characterized by brain overgrowth that occurs due to either increased number or size of neurons and glial cells. The former may be due to either increased neuronal proliferation or decreased apoptosis. The degree of brain overgrowth may be extensive, ranging from generalized MEG affecting the entire cortex-as with mutations in PTEN (phosphatase and tensin homolog on chromosome ten)-to unilateral hemispheric malformations-as in classic hemimegalencephaly (HME). On the other hand, some lesions are more focal or segmental. These developmental brain abnormalities may occur in isolation in some individuals, whereas others occur in the context of a syndrome involving dysmorphic features, skin findings, or other organ system involvement. Brain overgrowth disorders are often associated with malformations of cortical development, resulting in increased risk of epilepsy, intellectual disability, and autistic features, and some are associated with hydrocephalus. The past few years have witnessed a dramatic leap in our understanding of the molecular basis of brain overgrowth, particularly the identification of mosaic (or post-zygotic) mutations in core components of key cellular pathways such as the phosphatidylinositol 3-kinase (PI3K)-vakt murine thymoma viral oncogene homolog (AKT)-mTOR pathway. These molecular insights have broadened our view of brain overgrowth disorders that now appear to span a wide spectrum of overlapping phenotypic, neuroimaging, and neuropathologic features and molecular pathogenesis. These molecular advances also bring to light the possibility of pathway-based therapies for these often medically devastating developmental disorders.
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A child with epilepsy and skin lesions. J Pediatr 2013; 163:1522.e1. [PMID: 23810724 DOI: 10.1016/j.jpeds.2013.05.043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Accepted: 05/20/2013] [Indexed: 11/20/2022]
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Baek ST, Gibbs EM, Gleeson JG, Mathern GW. Hemimegalencephaly, a paradigm for somatic postzygotic neurodevelopmental disorders. Curr Opin Neurol 2013; 26:122-7. [PMID: 23449172 DOI: 10.1097/wco.0b013e32835ef373] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
PURPOSE OF REVIEW Combining human genomics and molecular biology, recent studies have made pivotal progress toward understanding the cause of hemimegalencephaly (HME) and other cerebral megalencephaly syndromes. The present article highlights recent advances of the genetic cause of these conditions, and considers the role of somatic postzygotic genetic lesions in brain maldevelopment. RECENT FINDINGS Studies over the past 12 months have identified de-novo somatic mutations as one possible cause in HME. The gene mutations involve components of the phosphatidylinositol 3-kinase (PI3K)-AKT (also known as protein kinase B)-mammalian target of rapamycin (mTOR) pathway and include PIK3CA, PIK3R2, AKT3, and MTOR. These mutations were identified by comparing genomic data obtained from surgically resected brain tissue with nondiseased tissue, and by single-neuron sequencing in combination with molecular biology techniques. The association between the somatic mutations and downstream activation of the PI3K-mTOR pathway suggests that HME is a neurodevelopmental disease caused by gain-of-function activation of the PI3K-AKT-mTOR pathway. SUMMARY The studies reviewed suggest that somatic mutations of the PI3K-AKT-mTOR pathway limited to the brain may represent one cause of HME. Dysregulation of this pathway has possible therapeutic potential in the identification of HME. Somatic mutations may be an important yet underappreciated disease mechanism in developmental neurological diseases.
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Affiliation(s)
- Seung Tae Baek
- Department of Neurosciences, Howard Hughes Medical Institute, University of California San Diego, La Jolla, California, USA
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