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Ma Q, Chen G, Li Y, Guo Z, Zhang X. The molecular genetics of PI3K/PTEN/AKT/mTOR pathway in the malformations of cortical development. Genes Dis 2024; 11:101021. [PMID: 39006182 PMCID: PMC11245990 DOI: 10.1016/j.gendis.2023.04.041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 04/07/2023] [Accepted: 04/30/2023] [Indexed: 07/16/2024] Open
Abstract
Malformations of cortical development (MCD) are a group of developmental disorders characterized by abnormal cortical structures caused by genetic or harmful environmental factors. Many kinds of MCD are caused by genetic variation. MCD is the common cause of intellectual disability and intractable epilepsy. With rapid advances in imaging and sequencing technologies, the diagnostic rate of MCD has been increasing, and many potential genes causing MCD have been successively identified. However, the high genetic heterogeneity of MCD makes it challenging to understand the molecular pathogenesis of MCD and to identify effective targeted drugs. Thus, in this review, we outline important events of cortical development. Then we illustrate the progress of molecular genetic studies about MCD focusing on the PI3K/PTEN/AKT/mTOR pathway. Finally, we briefly discuss the diagnostic methods, disease models, and therapeutic strategies for MCD. The information will facilitate further research on MCD. Understanding the role of the PI3K/PTEN/AKT/mTOR pathway in MCD could lead to a novel strategy for treating MCD-related diseases.
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Affiliation(s)
- Qing Ma
- NHC and CAMS Key Laboratory of Molecular Probe and Targeted Theranostics, Harbin Medical University, Harbin, Heilongjiang 150000, China
| | - Guang Chen
- Department of Urology, The Fourth Hospital of Harbin Medical University, Harbin, Heilongjiang 150000, China
| | - Ying Li
- NHC and CAMS Key Laboratory of Molecular Probe and Targeted Theranostics, Harbin Medical University, Harbin, Heilongjiang 150000, China
- Department of Child and Adolescent Health, School of Public Health, Harbin Medical University, Harbin, Heilongjiang 150000, China
| | - Zhenming Guo
- Institute for Regenerative Medicine, Shanghai East Hospital, Frontier Science Center for Stem Cell Research, School of Life Sciences and Technology, Tongji University, Shanghai 200120, China
| | - Xue Zhang
- NHC and CAMS Key Laboratory of Molecular Probe and Targeted Theranostics, Harbin Medical University, Harbin, Heilongjiang 150000, China
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2
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Man A, Di Scipio M, Grewal S, Suk Y, Trinari E, Ejaz R, Whitney R. The Genetics of Tuberous Sclerosis Complex and Related mTORopathies: Current Understanding and Future Directions. Genes (Basel) 2024; 15:332. [PMID: 38540392 PMCID: PMC10970281 DOI: 10.3390/genes15030332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Revised: 03/02/2024] [Accepted: 03/02/2024] [Indexed: 06/14/2024] Open
Abstract
The mechanistic target of rapamycin (mTOR) pathway serves as a master regulator of cell growth, proliferation, and survival. Upregulation of the mTOR pathway has been shown to cause malformations of cortical development, medically refractory epilepsies, and neurodevelopmental disorders, collectively described as mTORopathies. Tuberous sclerosis complex (TSC) serves as the prototypical mTORopathy. Characterized by the development of benign tumors in multiple organs, pathogenic variants in TSC1 or TSC2 disrupt the TSC protein complex, a negative regulator of the mTOR pathway. Variants in critical domains of the TSC complex, especially in the catalytic TSC2 subunit, correlate with increased disease severity. Variants in less crucial exons and non-coding regions, as well as those undetectable with conventional testing, may lead to milder phenotypes. Despite the assumption of complete penetrance, expressivity varies within families, and certain variants delay disease onset with milder neurological effects. Understanding these genotype-phenotype correlations is crucial for effective clinical management. Notably, 15% of patients have no mutation identified by conventional genetic testing, with the majority of cases postulated to be caused by somatic TSC1/TSC2 variants which present complex diagnostic challenges. Advancements in genetic testing, prenatal screening, and precision medicine hold promise for changing the diagnostic and treatment paradigm for TSC and related mTORopathies. Herein, we explore the genetic and molecular mechanisms of TSC and other mTORopathies, emphasizing contemporary genetic methods in understanding and diagnosing the condition.
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Affiliation(s)
- Alice Man
- Michael G. DeGroote School of Medicine, McMaster University, Hamilton, ON L8S 4L8, Canada
| | - Matteo Di Scipio
- Michael G. DeGroote School of Medicine, McMaster University, Hamilton, ON L8S 4L8, Canada
| | - Shan Grewal
- Michael G. DeGroote School of Medicine, McMaster University, Hamilton, ON L8S 4L8, Canada
| | - Yujin Suk
- Michael G. DeGroote School of Medicine, McMaster University, Hamilton, ON L8S 4L8, Canada
| | - Elisabetta Trinari
- Division of Developmental Pediatrics, Department of Pediatrics, McMaster Children’s Hospital, Hamilton, ON L8N 3Z5, Canada
| | - Resham Ejaz
- Division of Genetics, Department of Pediatrics, McMaster University, Hamilton, ON L8S 4L8, Canada
| | - Robyn Whitney
- Division of Neurology, Department of Pediatrics, McMaster University, Hamilton, ON L8S 4L8, Canada
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3
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Luca M, Piglionica M, Bagnulo R, Cardaropoli S, Carli D, Turchiano A, Coppo P, Pantaleo A, Iacoviello M, Ferrero GB, Mussa A, Resta N. The somatic p.T81dup variant in AKT3 gene underlies a mild cerebral phenotype and expands the spectrum including capillary malformation and lateralized overgrowth. Genes Chromosomes Cancer 2023; 62:703-709. [PMID: 37395289 DOI: 10.1002/gcc.23188] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2023] [Revised: 06/16/2023] [Accepted: 06/19/2023] [Indexed: 07/04/2023] Open
Abstract
Heterozygous germline or somatic variants in AKT3 gene can cause isolated malformations of cortical development (MCDs) such as focal cortical dysplasia, megalencephaly (MEG), Hemimegalencephaly (HME), dysplastic megalencephaly, and syndromic forms like megalencephaly-polymicrogyria-polydactyly-hydrocephalus syndrome, and megalencephaly-capillary malformation syndrome. This report describes a new case of HME and capillary malformation caused by a somatic AKT3 variant that differs from the common p.E17K variant described in literature. The patient's skin biopsy from the angiomatous region revealed an heterozygous likely pathogenic variant AKT3:c.241_243dup, p.(T81dup) that may affect the binding domain and downstream pathways. Compared to previously reported cases with a common E17K mosaic variant, the phenotype is milder and patients showed segmental overgrowth, an uncommon characteristic in AKT3 variant cases. These findings suggest that the severity of the disease may be influenced not only by the level of mosaicism but also by the type of variant. This report expands the phenotypic spectrum associated with AKT3 variants and highlights the importance of genomic analysis in patients with capillary malformation and MCDs.
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Affiliation(s)
- Maria Luca
- Department of Medical Sciences, University of Torino, Torino, Italy
| | - Marilidia Piglionica
- Department of Precision and Regenerative Medicine and Ionian Area (DiMePRe-J), Medical Genetics, University of Bari "Aldo Moro", Bari, Italy
| | - Rosanna Bagnulo
- Department of Precision and Regenerative Medicine and Ionian Area (DiMePRe-J), Medical Genetics, University of Bari "Aldo Moro", Bari, Italy
| | - Simona Cardaropoli
- Department of Public Health and Pediatric Sciences, University of Torino, Torino, Italy
| | - Diana Carli
- Department of Medical Sciences, University of Torino, Torino, Italy
| | - Antonella Turchiano
- Department of Precision and Regenerative Medicine and Ionian Area (DiMePRe-J), Medical Genetics, University of Bari "Aldo Moro", Bari, Italy
| | - Paola Coppo
- Pediatric Dermatology Unit, Regina Margherita Children's Hospital, Torino, Italy
| | - Antonino Pantaleo
- National Institute of Gastroenterology-IRCCS "Saverio de Bellis", Bari, Italy
| | - Matteo Iacoviello
- Department of Precision and Regenerative Medicine and Ionian Area (DiMePRe-J), Medical Genetics, University of Bari "Aldo Moro", Bari, Italy
| | | | - Alessandro Mussa
- Department of Public Health and Pediatric Sciences, University of Torino, Torino, Italy
- Pediatric Clinical Genetics, Regina Margherita Children Hospital, Torino, Italy
| | - Nicoletta Resta
- Department of Precision and Regenerative Medicine and Ionian Area (DiMePRe-J), Medical Genetics, University of Bari "Aldo Moro", Bari, Italy
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4
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Shelkowitz E, Stence NV, Neuberger I, Park KL, Saenz MS, Pao E, Oyama N, Friedman SD, Shaw DWW, Mirzaa GM. Variants in PTEN Are Associated With a Diverse Spectrum of Cortical Dysplasia. Pediatr Neurol 2023; 147:154-162. [PMID: 37619436 DOI: 10.1016/j.pediatrneurol.2023.06.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 04/12/2023] [Accepted: 06/16/2023] [Indexed: 08/26/2023]
Abstract
BACKGROUND Inactivating mutations in PTEN are among the most common causes of megalencephaly. Activating mutations in other nodes of the PI3K/AKT/MTOR signaling pathway are recognized as a frequent cause of cortical brain malformations. Only recently has PTEN been associated with cortical malformations, and analyses of their prognostic significance have been limited. METHODS Retrospective neuroimaging analysis and detailed chart review were conducted on 20 participants identified with pathogenic or likely pathogenic mutations in PTEN and a cortical brain malformation present on brain magnetic resonance imaging. RESULTS Neuroimaging analysis revealed four main cerebral phenotypes-hemimegalencephaly, focal cortical dysplasia, polymicrogyria (PMG), and a less severe category, termed "macrocephaly with complicated gyral pattern" (MCG). Although a high proportion of participants (90%) had neurodevelopmental findings on presentation, outcomes varied and were favorable in over half of participants. Consistent with prior work, 39% of participants had autism spectrum disorder and 19% of participants with either pure-PMG or pure-MCG phenotypes had epilepsy. Megalencephaly and systemic overgrowth were common, but other systemic features of PTEN-hamartoma tumor syndrome were absent in over one-third of participants. CONCLUSIONS A spectrum of cortical dysplasias is present in individuals with inactivating mutations in PTEN. Future studies are needed to clarify the prognostic significance of each cerebral phenotype, but overall, we conclude that despite a high burden of neurodevelopmental disease, long-term outcomes may be favorable. Germline testing for PTEN mutations should be considered in cases of megalencephaly and cortical brain malformations even in the absence of other findings, including cognitive impairment.
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Affiliation(s)
- Emily Shelkowitz
- Department of Pediatrics, University of Washington, Seattle, Washington.
| | | | - Ilana Neuberger
- Department of Radiology, University of Colorado, Aurora, Colorado
| | - Kristen L Park
- Department of Pediatrics, University of Colorado, Aurora, Colorado
| | | | - Emily Pao
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington
| | - Nora Oyama
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington
| | - Seth D Friedman
- Department of Radiology, Seattle Children's Hospital, University of Washington, Seattle, Washington
| | - Dennis W W Shaw
- Department of Radiology, Seattle Children's Hospital, University of Washington, Seattle, Washington
| | - Ghayda M Mirzaa
- Department of Pediatrics, University of Washington, Seattle, Washington; Brotman Baty Institute for Precision Medicine, Seattle, Washington.
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5
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Yoh Y, Shiohama T, Uchida T, Ebata R, Kobayashi H, Okunushi K, Kato M, Watanabe K, Nakashima M, Saitsu H, Hamada H. Case report: Progressive pulmonary artery hypertension in a case of megalencephaly-capillary malformation syndrome. Front Genet 2023; 14:1221745. [PMID: 37614820 PMCID: PMC10442816 DOI: 10.3389/fgene.2023.1221745] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Accepted: 07/24/2023] [Indexed: 08/25/2023] Open
Abstract
Megalencephaly-capillary malformation syndrome (MCAP, OMIM # 602501) is caused by hyperactivity of the thephosphoinositide-3-kinase (PI3K)-Vakt murine thymoma viral oncogene homolog (AKT)-mammalian target of rapamycin (mTOR) pathway, which results in megalencephaly, capillary malformations, asymmetrical overgrowth, and connective tissue dysplasia. Herein, we report the case of a 7-month-old girl with MCAP due to a PIK3CA somatic mosaic variant who presented with atrial tachycardia, finally diagnosed as pulmonary arterial hypertension (PAH). Oxygen therapy and sildenafil decreased pulmonary blood pressure and improved atrial tachycardia. Previous studies reported an association between the PI3K/AKT/mTOR pathway and abnormal pulmonary arterial smooth muscle cell proliferation, which may be associated with PAH. PAH should be considered a potentially lethal complication in MCAP patients, even when no structural cardiac abnormalities are identified in the neonatal period.
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Affiliation(s)
- Yuri Yoh
- Department of Pediatrics, Chiba University Hospital, Chiba, Japan
| | - Tadashi Shiohama
- Department of Pediatrics, Chiba University Hospital, Chiba, Japan
| | - Tomoko Uchida
- Department of Pediatrics, Chiba University Hospital, Chiba, Japan
| | - Ryota Ebata
- Department of Pediatrics, Chiba University Hospital, Chiba, Japan
| | | | - Kentaro Okunushi
- Department of Pediatrics, Chiba University Hospital, Chiba, Japan
| | - Mitsuhiro Kato
- Department of Pediatrics, Showa University School of Medicine, Tokyo, Japan
| | - Kazuki Watanabe
- Department of Biochemistry, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Mitsuko Nakashima
- Department of Biochemistry, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Hirotomo Saitsu
- Department of Biochemistry, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Hiromichi Hamada
- Department of Pediatrics, Chiba University Hospital, Chiba, Japan
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6
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Sarma K, Nayak MK, Mishra B, Gaikwad SB. Megalencephaly-Capillary Malformation-Polymicrogyria Syndrome (MCAP): A Rare Dynamic Genetic Disorder. Cureus 2022; 14:e25123. [PMID: 35733479 PMCID: PMC9205759 DOI: 10.7759/cureus.25123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/18/2022] [Indexed: 12/03/2022] Open
Abstract
Megalencephaly-capillary malformation-polymicrogyria syndrome (MCAP) is an uncommon malformation syndrome, characterized by primary megalencephaly, capillary malformations of the midline face and body, or distal limb anomalies such as syndactyly and polymicrogyria. Herein, we report a young male child, who presented with complaints of increasing head size, delay in speech, and one episode of focal seizure with distinctive morphological and neuroradiological manifestations which led to the diagnosis of MCAP. We have also reviewed recently published literature and the various diagnostic criteria proposed by authors to achieve the early clinical diagnosis of these patients in the outpatient department.
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7
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Moloney PB, Cavalleri GL, Delanty N. Epilepsy in the mTORopathies: opportunities for precision medicine. Brain Commun 2021; 3:fcab222. [PMID: 34632383 PMCID: PMC8495134 DOI: 10.1093/braincomms/fcab222] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 08/23/2021] [Accepted: 08/30/2021] [Indexed: 01/16/2023] Open
Abstract
The mechanistic target of rapamycin signalling pathway serves as a ubiquitous regulator of cell metabolism, growth, proliferation and survival. The main cellular activity of the mechanistic target of rapamycin cascade funnels through mechanistic target of rapamycin complex 1, which is inhibited by rapamycin, a macrolide compound produced by the bacterium Streptomyces hygroscopicus. Pathogenic variants in genes encoding upstream regulators of mechanistic target of rapamycin complex 1 cause epilepsies and neurodevelopmental disorders. Tuberous sclerosis complex is a multisystem disorder caused by mutations in mechanistic target of rapamycin regulators TSC1 or TSC2, with prominent neurological manifestations including epilepsy, focal cortical dysplasia and neuropsychiatric disorders. Focal cortical dysplasia type II results from somatic brain mutations in mechanistic target of rapamycin pathway activators MTOR, AKT3, PIK3CA and RHEB and is a major cause of drug-resistant epilepsy. DEPDC5, NPRL2 and NPRL3 code for subunits of the GTPase-activating protein (GAP) activity towards Rags 1 complex (GATOR1), the principal amino acid-sensing regulator of mechanistic target of rapamycin complex 1. Germline pathogenic variants in GATOR1 genes cause non-lesional focal epilepsies and epilepsies associated with malformations of cortical development. Collectively, the mTORopathies are characterized by excessive mechanistic target of rapamycin pathway activation and drug-resistant epilepsy. In the first large-scale precision medicine trial in a genetically mediated epilepsy, everolimus (a synthetic analogue of rapamycin) was effective at reducing seizure frequency in people with tuberous sclerosis complex. Rapamycin reduced seizures in rodent models of DEPDC5-related epilepsy and focal cortical dysplasia type II. This review outlines a personalized medicine approach to the management of epilepsies in the mTORopathies. We advocate for early diagnostic sequencing of mechanistic target of rapamycin pathway genes in drug-resistant epilepsy, as identification of a pathogenic variant may point to an occult dysplasia in apparently non-lesional epilepsy or may uncover important prognostic information including, an increased risk of sudden unexpected death in epilepsy in the GATORopathies or favourable epilepsy surgery outcomes in focal cortical dysplasia type II due to somatic brain mutations. Lastly, we discuss the potential therapeutic application of mechanistic target of rapamycin inhibitors for drug-resistant seizures in GATOR1-related epilepsies and focal cortical dysplasia type II.
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Affiliation(s)
- Patrick B Moloney
- FutureNeuro, the Science Foundation Ireland Research Centre for Chronic and Rare Neurological Diseases, Royal College of Surgeons in Ireland, Dublin, D02 VN51, Ireland
| | - Gianpiero L Cavalleri
- FutureNeuro, the Science Foundation Ireland Research Centre for Chronic and Rare Neurological Diseases, Royal College of Surgeons in Ireland, Dublin, D02 VN51, Ireland
| | - Norman Delanty
- FutureNeuro, the Science Foundation Ireland Research Centre for Chronic and Rare Neurological Diseases, Royal College of Surgeons in Ireland, Dublin, D02 VN51, Ireland
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8
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Park GB, Jeong JY, Kim D. GLUT5 regulation by AKT1/3-miR-125b-5p downregulation induces migratory activity and drug resistance in TLR-modified colorectal cancer cells. Carcinogenesis 2021; 41:1329-1340. [PMID: 32649737 DOI: 10.1093/carcin/bgaa074] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 05/26/2020] [Accepted: 07/08/2020] [Indexed: 12/16/2022] Open
Abstract
In cancer, resistance to chemotherapy is one of the main reasons for therapeutic failure. Cells that survive after treatment with anticancer drugs undergo various changes, including in cell metabolism. In this study, we investigated the effects of AKT-mediated miR-125b-5p alteration on metabolic changes and examined how these molecules enhance migration and induce drug resistance in colon cancer cells. AKT1 and AKT3 activation in drug-resistant colon cancer cells caused aberrant downregulation of miR-125b-5p, leading to GLUT5 expression. Targeted inhibition of AKT1 and AKT3 restored miR-125b-5p expression and prevented glycolysis- and lipogenesis-related enzyme activation. In addition, restoring the level of miR-125b-5p by transfection with the mimic sequence not only significantly blocked the production of lactate and intracellular fatty acids but also suppressed the migration and invasion of chemoresistant colon cancer cells. GLUT5 silencing with small interfering RNA attenuated mesenchymal marker expression and migratory activity in drug-resistant colon cancer cells. Additionally, treatment with 2,5-anhydro-d-mannitol resensitized chemoresistant cancer cells to oxaliplatin and 5-fluorouracil. In conclusion, our findings suggest that changes in miR-125b-5p and GLUT5 expression after chemotherapy can serve as a new marker to indicate metabolic change-induced migration and drug resistance development.
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Affiliation(s)
- Ga-Bin Park
- Department of Biochemistry, Kosin University College of Medicine, Busan, Republic of Korea
| | - Jee-Yeong Jeong
- Department of Biochemistry, Kosin University College of Medicine, Busan, Republic of Korea
| | - Daejin Kim
- Department of Anatomy, Inje University College of Medicine, Busan, Republic of Korea
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Pirozzi F, Lee B, Horsley N, Burkardt DD, Dobyns WB, Graham JM, Dentici ML, Cesario C, Schallner J, Porrmann J, Di Donato N, Sanchez-Lara PA, Mirzaa GM. Proximal variants in CCND2 associated with microcephaly, short stature, and developmental delay: A case series and review of inverse brain growth phenotypes. Am J Med Genet A 2021; 185:2719-2738. [PMID: 34087052 DOI: 10.1002/ajmg.a.62362] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 04/30/2021] [Accepted: 05/04/2021] [Indexed: 01/28/2023]
Abstract
Cyclin D2 (CCND2) is a critical cell cycle regulator and key member of the cyclin D2-CDK4 (DC) complex. De novo variants of CCND2 clustering in the distal part of the protein have been identified as pathogenic causes of brain overgrowth (megalencephaly, MEG) and severe cortical malformations in children including the megalencephaly-polymicrogyria-polydactyly-hydrocephalus (MPPH) syndrome. Megalencephaly-associated CCND2 variants are localized to the terminal exon and result in accumulation of degradation-resistant protein. We identified five individuals from three unrelated families with novel variants in the proximal region of CCND2 associated with microcephaly, mildly simplified cortical gyral pattern, symmetric short stature, and mild developmental delay. Identified variants include de novo frameshift variants and a dominantly inherited stop-gain variant segregating with the phenotype. This is the first reported association between proximal CCND2 variants and microcephaly, to our knowledge. This series expands the phenotypic spectrum of CCND2-related disorders and suggests that distinct classes of CCND2 variants are associated with reciprocal effects on human brain growth (microcephaly and megalencephaly due to possible loss or gain of protein function, respectively), adding to the growing paradigm of inverse phenotypes due to dysregulation of key brain growth genes.
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Affiliation(s)
- Filomena Pirozzi
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA
| | - Benson Lee
- Division of Medical Genetics, Department of Medicine, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California, USA
| | - Nicole Horsley
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA
| | - Deepika D Burkardt
- National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - William B Dobyns
- Division of Genetics and Metabolism, Department of Pediatrics, University of Minnesota, Minneapolis, Minnesota, USA
| | - John M Graham
- Medical Genetics Institute, Cedars-Sinai Medical Center, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - Maria L Dentici
- Medical Genetics Unit, Academic Department of Pediatrics, Bambino Gesù Children's Hospital, IRCSS, Rome, Italy.,Genetics and Rare Diseases Research Division, Bambino Gesù Children's Hospital, IRCSS, Rome, Italy
| | - Claudia Cesario
- Translational Cytogenomics Research Unit, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Jens Schallner
- Department of Neuropediatrics, School of Medicine, Carl Gustav Carus, TU Dresden, Dresden, Germany
| | - Joseph Porrmann
- Institute for Clinical Genetics, University Hospital, TU Dresden, Dresden, Germany
| | - Nataliya Di Donato
- Institute for Clinical Genetics, University Hospital, TU Dresden, Dresden, Germany
| | - Pedro A Sanchez-Lara
- Medical Genetics Institute, Cedars-Sinai Medical Center, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - Ghayda M Mirzaa
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA.,Division of Medical Genetics, Department of Pediatrics, University of Washington, Seattle, Washington, USA.,Brotman-Baty Institute for Precision Medicine, Seattle, Washington, USA.,Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington, USA
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10
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Wang Y, Peng J, Bai S, Yu H, He H, Fan C, Hao Y, Guan Y. A PIK3R2 Mutation in Familial Temporal Lobe Epilepsy as a Possible Pathogenic Variant. Front Genet 2021; 12:596709. [PMID: 34040629 PMCID: PMC8141861 DOI: 10.3389/fgene.2021.596709] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 04/06/2021] [Indexed: 11/13/2022] Open
Abstract
Temporal lobe epilepsy (TLE), the most common form of medically refractory focal epilepsy in adults, often requires surgery to alleviate seizures. By using next-generation sequencing, we identified a PIK3R2 mutation (NM_005027.4: c.265C > T; NP_005018.2: p.Arg89Cys) in a family with mesial temporal lobe epilepsy. PIK3R2 encodes p85β, the regulatory subunit of Class IA phosphoinositide 3-kinase (PI3K) and the mutation we identified in PIK3R2 seems to function unexpectedly as a possible pathogenic variant. The mutation is predicted to be potentially pathogenic by multiple bioinformatics tools. Through a functional assay, we verified that the mutation enhances the function of PI3K in induced pluripotent stem cells (iPSCs) derived from peripheral blood mononuclear cells (PBMCs) of the proband. Finally, pathological testing of the resected temporal lobe cortex showed that the expression of PIK3R2 was significantly higher in patients with refractory temporal lobe epilepsy than in those of non-epileptic diseases as a control group. It can be inferred that PIK3R2 might play an important role in the development of TLE.
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Affiliation(s)
- Yishu Wang
- Department of Neurology, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Jing Peng
- Department of Neurology, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Shuwei Bai
- Department of Neurology, The Second Affiliated Hospital of Xinjiang Medical University, Ürümqi, China
| | - Haojun Yu
- Department of Neurology, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Hong He
- School of Medical Instrument and Food Engineering, University of Shanghai for Science and Technology, Shanghai, China
| | - Chunxiang Fan
- TCM Department, Shanghai Punan Hospital of Pudong New District, Shanghai, China
| | - Yong Hao
- Department of Neurology, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Department of Neurology, Ningbo Hangzhou Bay Hospital, Ningbo, China
| | - Yangtai Guan
- Department of Neurology, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
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11
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Prenatal diagnosis and molecular cytogenetic characterization of a chromosome 1q42.3-q44 deletion in a fetus associated with ventriculomegaly on prenatal ultrasound. Taiwan J Obstet Gynecol 2021; 59:598-603. [PMID: 32653137 DOI: 10.1016/j.tjog.2020.05.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/20/2020] [Indexed: 11/21/2022] Open
Abstract
OBJECTIVE We present prenatal diagnosis and molecular cytogenetic characterization of a chromosome 1q42.3-q44 deletion in a fetus associated with ventriculomegaly on prenatal ultrasound, and we discuss the genotype-phenotype correlation. CASE REPORT A 36-year-old woman underwent amniocentesis at 17 weeks of gestation because of advanced maternal age. Amniocentesis revealed a karyotype of 46,XX,del(1) (q42.3q44). Simultaneous array comparative genomic hybridization analysis on uncultured amniocytes revealed arr 1q42.3q44 (234,747,397-246,081,267) × 1 [GRCh37 (hg19)] with an 11.33-Mb 1q42.3-q44 deletion encompassing RGS7, FH, CEP170, AKT3, ZBTB18 and HNRNPU. The parental karyotypes were normal. Prenatal ultrasound at 20 weeks of gestation revealed bilateral ventriculomegaly and dilation of the third ventricle. The pregnancy was subsequently terminated, and a malformed female fetus was delivered with characteristic facial dysmorphism. Postnatal conventional and molecular cytogenetic analyses confirmed the prenatal diagnosis. Polymorphic DNA marker analysis showed a paternal origin of the distal 1q deletion in the fetus. CONCLUSION Fetuses with a chromosome 1q42.3-q44 deletion may present ventriculomegaly on prenatal ultrasound. Prenatal diagnosis of ventriculomegaly should include a differential diagnosis of chromosome 1q distal deletions, and aCGH is useful under such a circumstance.
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Shi X, Lim Y, Myers AK, Stallings BL, Mccoy A, Zeiger J, Scheck J, Cho G, Marsh ED, Mirzaa GM, Tao T, Golden JA. PIK3R2/Pik3r2 Activating Mutations Result in Brain Overgrowth and EEG Changes. Ann Neurol 2020; 88:1077-1094. [PMID: 32856318 PMCID: PMC8176885 DOI: 10.1002/ana.25890] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Revised: 08/23/2020] [Accepted: 08/24/2020] [Indexed: 01/23/2023]
Abstract
OBJECTIVE Mutations in phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) complex have been associated with a broad spectrum of brain and organ overgrowth syndromes. For example, mutations in phosphatidylinositol-3-kinase regulatory subunit 2 (PIK3R2) have been identified in human patients with megalencephaly polymicrogyria polydactyly hydrocephalus (MPPH) syndrome, which includes brain overgrowth. To better understand the pathogenesis of PIK3R2-related mutations, we have developed and characterized a murine model. METHODS We generated a knock-in mouse model for the most common human PIK3R2 mutation, p.G373R (p.G367R in mice) using CRISPR/Cas9. The mouse phenotypes, including brain size, seizure activity, cortical lamination, cell proliferation/size/density, interneuron migration, and PI3K pathway activation, were analyzed using standard methodologies. For human patients with PIK3R2 mutations, clinical data (occipitofrontal circumference [OFC] and epilepsy) were retrospectively obtained from our clinical records (published / unpublished). RESULTS The PI3K-AKT pathway was hyperactivated in these mice, confirming the p.G367R mutation is an activating mutation in vivo. Similar to human patients with PIK3R2 mutations, these mice have enlarged brains. We found cell size to be increased but not cell numbers. The embryonic brain showed mild defects in cortical lamination, although not observed in the mature brain. Furthermore, electroencephalogram (EEG) recordings from mutant mice showed background slowing and rare seizures, again similar to our observations in human patients. INTERPRETATION We have generated a PIK3R2 mouse model that exhibits megalencephaly and EEG changes, both of which overlap with human patients. Our data provide novel insight into the pathogenesis of the human disease caused by PIK3R2 p.G373R mutation. We anticipate this model will be valuable in testing therapeutic options for human patients with MPPH. ANN NEUROL 2020;88:1077-1094.
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Affiliation(s)
- Xiuyu Shi
- State Key Laboratory of Stress Cell Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, 361005, China
- Department of Pathology, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Youngshin Lim
- Department of Pathology, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Abigail K. Myers
- Department of Pathology, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Brenna L. Stallings
- Department of Pathology, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Almedia Mccoy
- Departments of Neurology and Pediatrics, Division of Child Neurology, Children’s Hospital of Philadelphia, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Jordan Zeiger
- Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, WA 98101, USA
| | - Joshua Scheck
- Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, WA 98101, USA
| | - Ginam Cho
- Department of Pathology, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Eric D. Marsh
- Departments of Neurology and Pediatrics, Division of Child Neurology, Children’s Hospital of Philadelphia, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Ghayda M. Mirzaa
- Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, WA 98101, USA
- Department of Pediatrics, University of Washington, Seattle, WA 98195, USA
- Brotman Baty Institute for Precision Medicine, Seattle, WA 98195, USA
| | - Tao Tao
- State Key Laboratory of Stress Cell Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, 361005, China
| | - Jeffrey A. Golden
- Department of Pathology, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115, USA
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13
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Szalai R, Melegh BI, Till A, Ripszam R, Csabi G, Acharya A, Schrauwen I, Leal SM, Komoly S, Kosztolanyi G, Hadzsiev K. Maternal mosaicism underlies the inheritance of a rare germline AKT3 variant which is responsible for megalencephaly-polymicrogyria-polydactyly-hydrocephalus syndrome in two Roma half-siblings. Exp Mol Pathol 2020; 115:104471. [DOI: 10.1016/j.yexmp.2020.104471] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 04/03/2020] [Accepted: 05/18/2020] [Indexed: 10/24/2022]
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Dobyns WB, Mirzaa GM. Megalencephaly syndromes associated with mutations of core components of the PI3K-AKT-MTOR pathway: PIK3CA, PIK3R2, AKT3, and MTOR. AMERICAN JOURNAL OF MEDICAL GENETICS PART C-SEMINARS IN MEDICAL GENETICS 2019; 181:582-590. [PMID: 31441589 DOI: 10.1002/ajmg.c.31736] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Revised: 07/15/2019] [Accepted: 07/16/2019] [Indexed: 11/09/2022]
Abstract
Megalencephaly (MEG) is a developmental abnormality of brain growth characterized by early onset, often progressive, brain overgrowth. Focal forms of megalencephaly associated with cortical dysplasia, such as hemimegalencephaly and focal cortical dysplasia, are common causes of focal intractable epilepsy in children. The increasing use of high throughput sequencing methods, including high depth sequencing to more accurately detect and quantify mosaic mutations, has allowed us to identify the molecular etiologies of many MEG syndromes, including most notably the PI3K-AKT-MTOR related MEG disorders. Thorough molecular and clinical characterization of affected individuals further allow us to derive preliminary genotype-phenotype correlations depending on the gene, mutation, level of mosaicism, and tissue distribution. Our review of published data on these disorders so far shows that mildly activating variants (that are typically constitutional or germline) are associated with diffuse megalencephaly with intellectual disability and/or autism spectrum disorder; moderately activating variants (that are typically high-level mosaic) are associated with megalencephaly with pigmentary abnormalities of the skin; and strongly activating variants (that are usually very low-level mosaic) are associated with focal brain malformations including hemimegalencephaly and focal cortical dysplasia. Accurate molecular diagnosis of these disorders is undoubtedly crucial to more optimally treat children with these disorders using PI3K-AKT-MTOR pathway inhibitors.
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Affiliation(s)
- William B Dobyns
- University of Washington School of Medicine, Seattle, Washington.,Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington
| | - Ghayda M Mirzaa
- University of Washington School of Medicine, Seattle, Washington.,Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington
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15
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Dornan GL, Burke JE. Molecular Mechanisms of Human Disease Mediated by Oncogenic and Primary Immunodeficiency Mutations in Class IA Phosphoinositide 3-Kinases. Front Immunol 2018; 9:575. [PMID: 29616047 PMCID: PMC5868324 DOI: 10.3389/fimmu.2018.00575] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 03/07/2018] [Indexed: 12/13/2022] Open
Abstract
The signaling lipid phosphatidylinositol 3,4,5, trisphosphate (PIP3) is an essential mediator of many vital cellular processes, including growth, survival, and metabolism. PIP3 is generated through the action of the class I phosphoinositide 3-kinases (PI3K), and their activity is tightly controlled through interactions with regulatory proteins and activating stimuli. The class IA PI3Ks are composed of three distinct p110 catalytic subunits (p110α, p110β, and p110δ), and they play different roles in specific tissues due to disparities in both expression and engagement downstream of cell-surface receptors. Disruption of PI3K regulation is a frequent driver of numerous human diseases. Activating mutations in the PIK3CA gene encoding the p110α catalytic subunit of class IA PI3K are frequently mutated in several cancer types, and mutations in the PIK3CD gene encoding the p110δ catalytic subunit have been identified in primary immunodeficiency patients. All class IA p110 subunits interact with p85 regulatory subunits, and mutations/deletions in different p85 regulatory subunits have been identified in both cancer and primary immunodeficiencies. In this review, we will summarize our current understanding for the molecular basis of how class IA PI3K catalytic activity is regulated by p85 regulatory subunits, and how activating mutations in the PI3K catalytic subunits PIK3CA and PIK3CD (p110α, p110δ) and regulatory subunits PIK3R1 (p85α) mediate PI3K activation and human disease.
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Affiliation(s)
- Gillian L Dornan
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC, Canada
| | - John E Burke
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC, Canada
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16
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Alcantara D, Timms AE, Gripp K, Baker L, Park K, Collins S, Cheng C, Stewart F, Mehta SG, Saggar A, Sztriha L, Zombor M, Caluseriu O, Mesterman R, Van Allen MI, Jacquinet A, Ygberg S, Bernstein JA, Wenger AM, Guturu H, Bejerano G, Gomez-Ospina N, Lehman A, Alfei E, Pantaleoni C, Conti V, Guerrini R, Moog U, Graham Jr. JM, Hevner R, Dobyns WB, O’Driscoll M, Mirzaa GM. Mutations of AKT3 are associated with a wide spectrum of developmental disorders including extreme megalencephaly. Brain 2017; 140:2610-2622. [PMID: 28969385 PMCID: PMC6080423 DOI: 10.1093/brain/awx203] [Citation(s) in RCA: 87] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 06/13/2017] [Accepted: 07/04/2017] [Indexed: 11/12/2022] Open
Abstract
Mutations of genes within the phosphatidylinositol-3-kinase (PI3K)-AKT-MTOR pathway are well known causes of brain overgrowth (megalencephaly) as well as segmental cortical dysplasia (such as hemimegalencephaly, focal cortical dysplasia and polymicrogyria). Mutations of the AKT3 gene have been reported in a few individuals with brain malformations, to date. Therefore, our understanding regarding the clinical and molecular spectrum associated with mutations of this critical gene is limited, with no clear genotype-phenotype correlations. We sought to further delineate this spectrum, study levels of mosaicism and identify genotype-phenotype correlations of AKT3-related disorders. We performed targeted sequencing of AKT3 on individuals with these phenotypes by molecular inversion probes and/or Sanger sequencing to determine the type and level of mosaicism of mutations. We analysed all clinical and brain imaging data of mutation-positive individuals including neuropathological analysis in one instance. We performed ex vivo kinase assays on AKT3 engineered with the patient mutations and examined the phospholipid binding profile of pleckstrin homology domain localizing mutations. We identified 14 new individuals with AKT3 mutations with several phenotypes dependent on the type of mutation and level of mosaicism. Our comprehensive clinical characterization, and review of all previously published patients, broadly segregates individuals with AKT3 mutations into two groups: patients with highly asymmetric cortical dysplasia caused by the common p.E17K mutation, and patients with constitutional AKT3 mutations exhibiting more variable phenotypes including bilateral cortical malformations, polymicrogyria, periventricular nodular heterotopia and diffuse megalencephaly without cortical dysplasia. All mutations increased kinase activity, and pleckstrin homology domain mutants exhibited enhanced phospholipid binding. Overall, our study shows that activating mutations of the critical AKT3 gene are associated with a wide spectrum of brain involvement ranging from focal or segmental brain malformations (such as hemimegalencephaly and polymicrogyria) predominantly due to mosaic AKT3 mutations, to diffuse bilateral cortical malformations, megalencephaly and heterotopia due to constitutional AKT3 mutations. We also provide the first detailed neuropathological examination of a child with extreme megalencephaly due to a constitutional AKT3 mutation. This child has one of the largest documented paediatric brain sizes, to our knowledge. Finally, our data show that constitutional AKT3 mutations are associated with megalencephaly, with or without autism, similar to PTEN-related disorders. Recognition of this broad clinical and molecular spectrum of AKT3 mutations is important for providing early diagnosis and appropriate management of affected individuals, and will facilitate targeted design of future human clinical trials using PI3K-AKT pathway inhibitors.
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Affiliation(s)
- Diana Alcantara
- Genome Damage and Stability Centre, University of Sussex, Sussex, UK
| | - Andrew E Timms
- Center for Developmental Biology and Regenerative Medicine, Seattle Children’s Research Institute, Seattle, WA, USA
| | - Karen Gripp
- Department of Pediatrics, Sidney Kimmel Medical School, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
- Division of Medical Genetics, A.I. duPont Hospital for Children, Wilmington, Delaware, USA
| | - Laura Baker
- Department of Pediatrics, Sidney Kimmel Medical School, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
- Division of Medical Genetics, A.I. duPont Hospital for Children, Wilmington, Delaware, USA
| | - Kaylee Park
- Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, Washington, USA
| | - Sarah Collins
- Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, Washington, USA
| | - Chi Cheng
- Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, Washington, USA
| | - Fiona Stewart
- Belfast Health and Social Care Trust, Belfast, Northern Ireland, UK
| | - Sarju G Mehta
- East Anglian Medical Genetics Service, Addenbrookes Hospital, Cambridge, UK
| | - Anand Saggar
- South West Thames Regional Genetic Services, St. George’s NHS Trust and St. George’s Hospital Medical School, London, UK
| | - László Sztriha
- Department of Pediatrics, University of Szeged, Szeged, Hungary
| | - Melinda Zombor
- Department of Pediatrics, University of Szeged, Szeged, Hungary
| | - Oana Caluseriu
- Department of Medical Genetics, Department of Pediatrics, University of Alberta, Edmonton, AB, Canada
| | - Ronit Mesterman
- Division of Pediatric Neurology, Developmental Pediatric Rehabilitation and Autism Spectrum Disorder, McMaster University, Hamilton, ON, Canada
| | - Margot I Van Allen
- Department of Medical Genetics, University of British Columbia, Vancouver, Canada
- B.C. Children’s Hospital Research Centre, Vancouver, BC Canada
| | - Adeline Jacquinet
- Center for Human Genetics, Centre Hospitalier Universitaire and University of Liège, Liège, Belgium
| | - Sofia Ygberg
- Neuropediatric Unit and Centre for Inherited Metabolic Diseases (CMMS), Karolinska University Hospital, Stockholm, Sweden
| | - Jonathan A Bernstein
- Department of Pediatrics, Stanford University School of Medicine, Stanford, California, USA
| | - Aaron M Wenger
- Department of Pediatrics, Stanford University School of Medicine, Stanford, California, USA
| | - Harendra Guturu
- Department of Pediatrics, Stanford University School of Medicine, Stanford, California, USA
| | - Gill Bejerano
- Department of Pediatrics, Stanford University School of Medicine, Stanford, California, USA
- Department of Computer Science, School of Engineering, Stanford University School of Medicine, Stanford, California, USA
- Department of Developmental Biology, School of Medicine, Stanford University School of Medicine, Stanford, California, USA
| | - Natalia Gomez-Ospina
- Department of Pediatrics, Stanford University School of Medicine, Stanford, California, USA
| | - Anna Lehman
- Department of Medical Genetics, University of British Columbia, Vancouver, Canada
| | - Enrico Alfei
- Developmental Neurology Unit, Department of Pediatric Neurosciences, Carlo Besta Neurological Institute, IRCCS Foundation, Milan, Italy
| | - Chiara Pantaleoni
- Developmental Neurology Unit, Department of Pediatric Neurosciences, Carlo Besta Neurological Institute, IRCCS Foundation, Milan, Italy
| | - Valerio Conti
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, A. Meyer Children’s Hospital, Florence, Italy
| | - Renzo Guerrini
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, A. Meyer Children’s Hospital, Florence, Italy
- IRCCS Stella Maris, Pisa, Italy
| | - Ute Moog
- Institute of Human Genetics, Heidelberg University, Heidelberg, Germany
| | - John M Graham Jr.
- Department of Pediatrics, Cedars-Sinai Medical Center, Harbor-UCLA Medical Center, David Geffen School of Medicine Los Angeles, California, USA
| | - Robert Hevner
- Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, Washington, USA
- Department of Neurological Surgery, University of Washington, Seattle, Washington, USA
| | - William B Dobyns
- Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, Washington, USA
- Division of Genetic Medicine, Department of Pediatrics, University of Washington, Seattle, Washington, USA
| | - Mark O’Driscoll
- Genome Damage and Stability Centre, University of Sussex, Sussex, UK
| | - Ghayda M Mirzaa
- Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, Washington, USA
- Division of Genetic Medicine, Department of Pediatrics, University of Washington, Seattle, Washington, USA
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17
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Takagi M, Dobashi K, Nagahara K, Kato M, Nishimura G, Fukuzawa R, Narumi S, Hasegawa T. A novel de novo germline mutation Glu40Lys in AKT3 causes megalencephaly with growth hormone deficiency. Am J Med Genet A 2017; 173:1071-1076. [PMID: 28190287 DOI: 10.1002/ajmg.a.38099] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Accepted: 11/23/2016] [Indexed: 11/10/2022]
Abstract
Germline or somatic gain-of-function mutations in the v-akt murine thymoma viral oncogene homolog 3 (AKT3) have been reported to cause syndromic megalencephaly. We describe a novel germline mutation, p.Glu40Lys, in AKT3. Phenotypically, the patient presented with megalencephaly with hypotonia, apparent connective tissue laxity, and growth hormone (GH) deficiency. To our knowledge, this is the first instance of a patient with megalencephaly with GH deficiency, harboring a germline de novo mutation in AKT3. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Masaki Takagi
- Department of Pediatrics, Keio University School of Medicine, Tokyo, Japan
| | - Kazushige Dobashi
- Department of Pediatrics, Showa University School of Medicine, Tokyo, Japan
| | - Keiko Nagahara
- Department of Pediatrics, Showa University School of Medicine, Tokyo, Japan
| | - Mitsuhiro Kato
- Department of Pediatrics, Showa University School of Medicine, Tokyo, Japan
| | - Gen Nishimura
- Department of Radiology, Tokyo Metropolitan Children's Medical Center, Tokyo, Japan
| | - Ryuji Fukuzawa
- Department of Pathology and Laboratory Medicine, Tokyo Metropolitan Children's Medical Center, Tokyo, Japan
| | - Satoshi Narumi
- Department of Pediatrics, Keio University School of Medicine, Tokyo, Japan.,Department of Molecular Endocrinology, National Research Institute for Child Health and Development, Tokyo, Japan
| | - Tomonobu Hasegawa
- Department of Pediatrics, Keio University School of Medicine, Tokyo, Japan
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18
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Negishi Y, Miya F, Hattori A, Johmura Y, Nakagawa M, Ando N, Hori I, Togawa T, Aoyama K, Ohashi K, Fukumura S, Mizuno S, Umemura A, Kishimoto Y, Okamoto N, Kato M, Tsunoda T, Yamasaki M, Kanemura Y, Kosaki K, Nakanishi M, Saitoh S. A combination of genetic and biochemical analyses for the diagnosis of PI3K-AKT-mTOR pathway-associated megalencephaly. BMC MEDICAL GENETICS 2017; 18:4. [PMID: 28086757 PMCID: PMC5237172 DOI: 10.1186/s12881-016-0363-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2016] [Accepted: 12/21/2016] [Indexed: 11/10/2022]
Abstract
Background Constitutive activation of the PI3K-AKT-mTOR pathway (mTOR pathway) underlies megalencephaly in many patients. Yet, prevalence of the involvement of the PI3K-AKT-mTOR pathway in patients with megalencephaly remains to be elucidated, and molecular diagnosis is challenging. Here, we have successfully established a combination of genetic and biochemical methods for diagnosis of mTOR pathway-associated megalencephaly, and have attempted to delineate the clinical characteristics of the disorder. Methods Thirteen patients with an increased head circumference and neurological symptoms participated in the study. To evaluate the activation of the mTOR pathway, we performed western blot analysis to determine the expression levels of phosphorylated S6 ribosomal protein (phospho-S6 protein) in lymphoblastoid cell lines from 12 patients. Multiplex targeted sequencing analysis for 15 genes involved in the mTOR pathway was performed on 12 patients, and whole-exome sequencing was performed on one additional patient. Clinical features and MRI findings were also investigated. Results We identified pathogenic mutations in six (AKT3, 1 patient; PIK3R2, 2 patients; PTEN, 3 patients) of the 13 patients. Increased expression of phospho-S6 protein was demonstrated in all five mutation-positive patients in whom western blotting was performed, as well as in three mutation-negative patients. Developmental delay, dysmorphic facial features were observed in almost all patients. Syndactyly/polydactyly and capillary malformations were not observed, even in patients with AKT3 or PIK3R2 mutations. There were no common phenotypes or MRI findings among these patients. Conclusions A combination of genetic and biochemical methods successfully identified mTOR pathway involvement in nine of 13 (approximately 70%) patients with megalencephaly, indicating a major contribution of the pathway to the pathogenesis of megalencephaly. Our combined approach could be useful to identify patients who are suitable for future clinical trials using an mTOR inhibitor.
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Affiliation(s)
- Yutaka Negishi
- Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-Cho, Mizuho-Ku, Nagoya, 467-8601, Japan
| | - Fuyuki Miya
- Department of Medical Science Mathematics, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan.,Laboratory for Medical Science Mathematics, RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
| | - Ayako Hattori
- Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-Cho, Mizuho-Ku, Nagoya, 467-8601, Japan
| | - Yoshikazu Johmura
- Department of Cell Biology, Graduate School of Medical Sciences, Nagoya City University, Nagoya, Japan.,Present address: Division of Cancer Cell Biology, Department of Cancer Biology, Instuite of Medical Science, The University of Tokyo, Tokyo, Japan
| | - Motoo Nakagawa
- Department of Radiology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Naoki Ando
- Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-Cho, Mizuho-Ku, Nagoya, 467-8601, Japan
| | - Ikumi Hori
- Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-Cho, Mizuho-Ku, Nagoya, 467-8601, Japan
| | - Takao Togawa
- Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-Cho, Mizuho-Ku, Nagoya, 467-8601, Japan
| | - Kohei Aoyama
- Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-Cho, Mizuho-Ku, Nagoya, 467-8601, Japan
| | - Kei Ohashi
- Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-Cho, Mizuho-Ku, Nagoya, 467-8601, Japan
| | - Shinobu Fukumura
- Department of Pediatrics, Sapporo Medical University School of Medicine, Sapporo, Japan
| | - Seiji Mizuno
- Department of Pediatrics, Central Hospital, Aichi Human Service Center, Aichi, Japan
| | - Ayako Umemura
- Department of Pediatric Neurology, Central Hospital, Aichi Human Service Center, Aichi, Japan
| | - Yoko Kishimoto
- Department of Pediatrics, Shimada Ryoiku Center Hachiouji, Tokyo, Japan
| | - Nobuhiko Okamoto
- Department of Medical Genetics, Osaka Medical Center and Research Institute for Maternal and Child Health, Osaka, Japan
| | - Mitsuhiro Kato
- Department of Pediatrics, Yamagata University Faculty of Medicine, Yamagata, Japan.,Present address: Department of Pediatrics, Showa University School of Medicine, Tokyo, Japan
| | - Tatsuhiko Tsunoda
- Department of Medical Science Mathematics, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan.,Laboratory for Medical Science Mathematics, RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
| | - Mami Yamasaki
- Department of Neurosurgery, Takatsuki General Hospital, Osaka, Japan
| | - Yonehiro Kanemura
- Division of Regenerative Medicine, Institute for Clinical Research, Osaka National Hospital, National Hospital Organization, Osaka, Japan.,Department of Neurosurgery, Osaka National Hospital, National Hospital Organization, Osaka, Japan
| | - Kenjiro Kosaki
- Center for Medical Genetics, Keio University School of Medicine, Tokyo, Japan
| | - Makoto Nakanishi
- Laboratory for Medical Science Mathematics, RIKEN Center for Integrative Medical Sciences, Yokohama, Japan.,Present address: Division of Cancer Cell Biology, Department of Cancer Biology, Instuite of Medical Science, The University of Tokyo, Tokyo, Japan
| | - Shinji Saitoh
- Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-Cho, Mizuho-Ku, Nagoya, 467-8601, Japan.
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19
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Wang L, Zhou K, Fu Z, Yu D, Huang H, Zang X, Mo X. Brain Development and Akt Signaling: the Crossroads of Signaling Pathway and Neurodevelopmental Diseases. J Mol Neurosci 2016; 61:379-384. [PMID: 28025777 PMCID: PMC5344939 DOI: 10.1007/s12031-016-0872-y] [Citation(s) in RCA: 108] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2016] [Accepted: 11/25/2016] [Indexed: 12/12/2022]
Abstract
Neurodevelopmental biology, coupled with the application of advanced histological, imaging, molecular, cellular, biochemical, and genetic approaches, has provided new insights into these intricate genetic, cellular, and molecular events. During telencephalic development, specific neural progenitor cells (NPCs) proliferate, differentiate into numerous cell types, migrate to their apposite positions, and form an integrated circuitry. Critical disturbance to this dynamic process via genetic and environmental risk can cause neurological disorders and disability. The phosphatidylinositol-3-OH kinase (PI3K)-Akt-mammalian target of rapamycin (mTOR) signaling cascade contributes to mediate various cellular processes, including cell proliferation and growth, and nutrient uptake. In light of its critical function, dysregulation of this node has been regarded as a root cause of several neurodevelopmental diseases, such as megalencephaly ("big brain"), microcephaly ("small brain"), autism spectrum disorders, intellectual disability, schizophrenia, and epilepsy. In this review, particular emphasis will be given to the PI3K-Akt-mTOR signaling pathway and their paramount importance in neurodevelopment of the cerebral neocortex, because of its critical roles in complex cognition, emotional regulation, language, and behaviors.
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Affiliation(s)
- Long Wang
- Department of Cardiothoracic Surgery, Children's Hospital of Nanjing Medical University, Nanjing, 210008, China
| | - Kai Zhou
- Department of Cardiothoracic Surgery, Children's Hospital of Nanjing Medical University, Nanjing, 210008, China
| | - Zhi Fu
- Department of Cardiothoracic Surgery, Children's Hospital of Nanjing Medical University, Nanjing, 210008, China
| | - Di Yu
- Department of Cardiothoracic Surgery, Children's Hospital of Nanjing Medical University, Nanjing, 210008, China
| | - Hesuyuan Huang
- Department of Cardiothoracic Surgery, Children's Hospital of Nanjing Medical University, Nanjing, 210008, China
| | - Xiaodong Zang
- Department of Cardiothoracic Surgery, Children's Hospital of Nanjing Medical University, Nanjing, 210008, China
| | - Xuming Mo
- Department of Cardiothoracic Surgery, Children's Hospital of Nanjing Medical University, Nanjing, 210008, China.
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20
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Abstract
Studies of syndromic hydrocephalus have led to the identification of >100 causative genes. Even though this work has illuminated numerous pathways associated with hydrocephalus, it has also highlighted the fact that the genetics underlying this phenotype are more complex than anticipated originally. Mendelian forms of hydrocephalus account for a small fraction of the genetic burden, with clear evidence of background-dependent effects of alleles on penetrance and expressivity of driver mutations in key developmental and homeostatic pathways. Here, we synthesize the currently implicated genes and inheritance paradigms underlying hydrocephalus, grouping causal loci into functional modules that affect discrete, albeit partially overlapping, cellular processes. These in turn have the potential to both inform pathomechanism and assist in the rational molecular classification of a clinically heterogeneous phenotype. Finally, we discuss conceptual methods that can lead to enhanced gene identification and dissection of disease basis, knowledge that will potentially form a foundation for the design of future therapeutics.
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Affiliation(s)
- Maria Kousi
- Center for Human Disease Modeling, Duke University School of Medicine, Durham, North Carolina 27701;
| | - Nicholas Katsanis
- Center for Human Disease Modeling, Duke University School of Medicine, Durham, North Carolina 27701;
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21
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Terrone G, Voisin N, Abdullah Alfaiz A, Cappuccio G, Vitiello G, Guex N, D'Amico A, James Barkovich A, Brunetti-Pierri N, Del Giudice E, Reymond A. De novo PIK3R2 variant causes polymicrogyria, corpus callosum hyperplasia and focal cortical dysplasia. Eur J Hum Genet 2016; 24:1359-62. [PMID: 26860062 DOI: 10.1038/ejhg.2016.7] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Revised: 12/08/2015] [Accepted: 12/16/2015] [Indexed: 11/09/2022] Open
Abstract
We report an 8-year-old boy with a complex cerebral malformation, intellectual disability, and complex partial seizures. Whole-exome sequencing revealed a yet unreported de novo variant in the PIK3R2 gene that was recently associated with megalencephaly-polymicrogyria-polydactyly-hydrocephalus (MPPH) syndrome and bilateral perisylvian polymicrogyria (BPP). Our patient showed cerebral abnormalities (megalencephaly, perisylvian polymicrogyria, and mega corpus callosum) that were consistent with these conditions. Imaging also showed right temporal anomalies suggestive of cortical dysplasia. Until now, only three variants (c.1117G>A (p.(G373R)), c.1126A>G (p.(K376E)) and c.1202T>C (p.(L401P))) affecting the SH2 domain of the PIK3R2 protein have been reported in MPPH and BPP syndromes. In contrast to the variants reported so far, the patient described herein exhibits the c.1669G>C (p.(D557H)) variant that affects a highly conserved residue at the interface with the PI3K catalytic subunit α. The phenotypic spectrum associated with variants in this gene and its pathway are likely to continue to expand as more cases are identified.
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Affiliation(s)
- Gaetano Terrone
- Department of Translational Medicine, Section of Pediatrics, Federico II University, Naples, Italy
| | - Norine Voisin
- Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland
| | - Ali Abdullah Alfaiz
- Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland.,Swiss Institute of Bioinformatics (SIB), Lausanne, Switzerland.,Bioinformatics Section, King Abdullah International Medical Research Center (KAIMRC), Riyadh, Kingdom of Saudi Arabia.,King Saud Bin Abdulaziz University for Health Sciences, Riyadh, Kingdom of Saudi Arabia
| | - Gerarda Cappuccio
- Department of Translational Medicine, Section of Pediatrics, Federico II University, Naples, Italy
| | - Giuseppina Vitiello
- Department of Translational Medicine, Section of Pediatrics, Federico II University, Naples, Italy
| | - Nicolas Guex
- Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland.,Swiss Institute of Bioinformatics (SIB), Lausanne, Switzerland
| | - Alessandra D'Amico
- Department of Diagnostic Imaging, Neuroradiology Unit, Federico II University, Naples, Italy
| | - A James Barkovich
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA, USA
| | - Nicola Brunetti-Pierri
- Department of Translational Medicine, Section of Pediatrics, Federico II University, Naples, Italy.,Telethon Institute of Genetics and Medicine, Pozzuoli, Naples, Italy
| | - Ennio Del Giudice
- Department of Translational Medicine, Section of Pediatrics, Federico II University, Naples, Italy
| | - Alexandre Reymond
- Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland
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22
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Mirzaa GM, Conti V, Timms AE, Smyser CD, Ahmed S, Carter M, Barnett S, Hufnagel RB, Goldstein A, Narumi-Kishimoto Y, Olds C, Collins S, Johnston K, Deleuze JF, Nitschké P, Friend K, Harris C, Goetsch A, Martin B, Boyle EA, Parrini E, Mei D, Tattini L, Slavotinek A, Blair E, Barnett C, Shendure J, Chelly J, Dobyns WB, Guerrini R. Characterisation of mutations of the phosphoinositide-3-kinase regulatory subunit, PIK3R2, in perisylvian polymicrogyria: a next-generation sequencing study. Lancet Neurol 2015; 14:1182-95. [PMID: 26520804 PMCID: PMC4672724 DOI: 10.1016/s1474-4422(15)00278-1] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Revised: 09/11/2015] [Accepted: 09/29/2015] [Indexed: 12/19/2022]
Abstract
Background Bilateral perisylvian polymicrogyria (BPP), the most common form of
regional polymicrogyria, causes the congenital bilateral perisylvian
syndrome, featuring oromotor dysfunction, cognitive impairment and epilepsy.
BPP is etiologically heterogeneous, but only a few genetic causes have been
reported. The aim of this study was to identify additional genetic
etiologies of BPP and delineate their frequency in this patient
population. Methods We performed child-parent (trio)-based whole exome sequencing (WES)
on eight children with BPP. Following the identification of mosaic
PIK3R2 mutations in two of these eight children, we
performed targeted screening of PIK3R2 in a cohort of 118
children with BPP who were ascertained from 1980 until 2015 using two
methods. First, we performed targeted sequencing of the entire
PIK3R2 gene by single molecule molecular inversion
probes (smMIPs) on 38 patients with BPP with normal-large head size. Second,
we performed amplicon sequencing of the recurrent PIK3R2
mutation (p.Gly373Arg) on 80 children with various types of polymicrogyria
including BPP. One additional patient underwent clinical WES independently,
and was included in this study given the phenotypic similarity to our
cohort. All patients included in this study were children (< 18 years of
age) with polymicrogyria enrolled in our research program. Findings Using WES, we identified a mosaic mutation (p.Gly373Arg) in the
regulatory subunit of the PI3K-AKT-MTOR pathway, PIK3R2, in
two children with BPP. Of the 38 patients with BPP and normal-large head
size who underwent targeted next generation sequencing by smMIPs, we
identified constitutional and mosaic PIK3R2 mutations in 17
additional children. In parallel, one patient was found to have the
recurrent PIK3R2 mutation by clinical WES. Seven patients
had BPP alone, and 13 had BPP in association with features of the
megalencephaly-polymicrogyria-polydactyly-hydrocephalus syndrome (MPPH).
Nineteen patients had the same mutation (Gly373Arg), and one had a nearby
missense mutation (p.Lys376Glu). Across the entire cohort, mutations were
constitutional in 12 and mosaic in eight patients. Among mosaic patients, we
observed substantial variation in alternate (mutant) allele levels ranging
from 2·5% (10/377) to 36·7% (39/106) of
reads, equivalent to 5–73·4% of cells analyzed.
Levels of mosaicism varied from undetectable to 17·1%
(37/216) of reads in blood-derived compared to 29·4%
(2030/6889) to 43·3% (275/634) in saliva-derived DNA. Interpretation Constitutional and mosaic mutations in the PIK3R2
gene are associated with a spectrum of developmental brain disorders ranging
from BPP with a normal head size to the
megalencephaly-polymicrogyria-polydactyly-hydrocephalus syndrome. The
phenotypic variability and low-level mosaicism challenging conventional
molecular methods have important implications for genetic testing and
counseling.
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Affiliation(s)
- Ghayda M Mirzaa
- Division of Genetic Medicine, Department of Pediatrics, University of Washington, Seattle, WA, USA; Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA.
| | - Valerio Conti
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Neuroscience Department, A Meyer Children's Hospital, University of Florence, Florence, Italy
| | - Andrew E Timms
- Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, Seattle, WA, USA
| | - Christopher D Smyser
- Department of Neurology and Pediatrics, Washington University School of Medicine, St Louis, MO, USA
| | - Sarah Ahmed
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA
| | - Melissa Carter
- Division of Clinical and Metabolic Genetics, The Hospital for Sick Children, Toronto, ON, Canada
| | - Sarah Barnett
- Division of Medical Genetics, University of Missouri, St Louis, MO, USA
| | - Robert B Hufnagel
- Division of Human Genetics, Cincinnati Children's Hospital, Cincinnati, OH, USA
| | - Amy Goldstein
- Division of Child Neurology, Children's Hospital of Pittsburgh, Pittsburgh, PA, USA
| | | | - Carissa Olds
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA
| | - Sarah Collins
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA
| | - Kathreen Johnston
- Genetics Department, Permanente Medical Group, San Francisco, CA, USA
| | | | - Patrick Nitschké
- Plateforme de Bioinformatique Paris-Descartes, Institut Imagine, Paris, France
| | - Kathryn Friend
- Genetics and Molecular Pathology, Women's and Children's Hospital, North Adelaide, SA, Australia
| | - Catharine Harris
- Division of Medical Genetics, University of Missouri, St Louis, MO, USA
| | - Allison Goetsch
- Division of Genetics, Birth Defects and Metabolism, Ann and Robert H Lurie Children's Hospital of Chicago, Chicago, IL, USA
| | - Beth Martin
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Evan August Boyle
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA
| | - Elena Parrini
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Neuroscience Department, A Meyer Children's Hospital, University of Florence, Florence, Italy
| | - Davide Mei
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Neuroscience Department, A Meyer Children's Hospital, University of Florence, Florence, Italy
| | - Lorenzo Tattini
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Neuroscience Department, A Meyer Children's Hospital, University of Florence, Florence, Italy
| | - Anne Slavotinek
- Department of Pediatrics, Division of Genetics, University of California, San Francisco, CA, USA
| | - Ed Blair
- Department of Clinical Genetics, Churchill Hospital, Oxford University Hospitals, Headington, UK
| | - Christopher Barnett
- South Australian Clinical Genetics Service, Women's and Children's Hospital/SA Pathology, North Adelaide, SA, Australia; Discipline of Pediatrics, University of Adelaide, Adelaide, Australia
| | - Jay Shendure
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Jamel Chelly
- Pôle de biologie, Hôpitaux Universitaires de Strasbourg, Strasbourg, France; IGBMC, Translational Medicine and Neurogenetics Department, Illkirch, France
| | - William B Dobyns
- Division of Genetic Medicine, Department of Pediatrics, University of Washington, Seattle, WA, USA; Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA
| | - Renzo Guerrini
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Neuroscience Department, A Meyer Children's Hospital, University of Florence, Florence, Italy; IRCCS Stella Maris Foundation, Pisa, Italy.
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23
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Nellist M, Schot R, Hoogeveen-Westerveld M, Neuteboom RF, van der Louw EJTM, Lequin MH, Bindels-de Heus K, Sibbles BJ, de Coo R, Brooks A, Mancini GMS. Germline activating AKT3 mutation associated with megalencephaly, polymicrogyria, epilepsy and hypoglycemia. Mol Genet Metab 2015; 114:467-73. [PMID: 25523067 DOI: 10.1016/j.ymgme.2014.11.018] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Revised: 11/28/2014] [Accepted: 11/28/2014] [Indexed: 10/24/2022]
Abstract
Activating germ-line and somatic mutations in AKT3 (OMIM 611223) are associated with megalencephaly-polymicrogyria-polydactyly-hydrocephalus syndrome (MPPH; OMIM # 615937) and megalencephaly-capillary malformation (MCAP; OMIM # 602501). Here we report an individual with megalencephaly, polymicrogyria, refractory epilepsy, hypoglycemia and a germline AKT3 mutation. At birth, head circumference was 43 cm (5 standard deviations above the mean). No organomegaly was present, but there was generalized hypotonia, joint and skin laxity, developmental delay and failure to thrive. At 6 months of age the patient developed infantile spasms that were resistant to antiepileptic polytherapy. Recurrent hypoglycemia was noted during treatment with adrenocorticotropic hormone but stabilized upon introduction of continuous, enriched feeding. The infantile spasms responded to the introduction of a ketogenic diet, but the hypoglycemia recurred until the diet was adjusted for increased resting energy expenditure. A novel, de novo AKT3 missense variant (exon 5; c.548T>A, p.(V183D)) was identified and shown to activate AKT3 by in vitro functional testing. We hypothesize that the sustained hypoglycemia in this patient is caused by increased glucose utilization due to activation of AKT3 signaling. This might explain the efficacy of the ketogenic diet in this individual.
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Affiliation(s)
- Mark Nellist
- Department of Clinical Genetics, Erasmus MC, Sophia Children's Hospital, Rotterdam, The Netherlands
| | - Rachel Schot
- Department of Clinical Genetics, Erasmus MC, Sophia Children's Hospital, Rotterdam, The Netherlands
| | | | - Rinze F Neuteboom
- Department of Child Neurology, Erasmus MC, Sophia Children's Hospital, Rotterdam, The Netherlands
| | | | - Maarten H Lequin
- Department of Radiology, Erasmus MC, Sophia Children's Hospital, Rotterdam, The Netherlands
| | - Karen Bindels-de Heus
- Department of Pediatrics, Erasmus MC, Sophia Children's Hospital, Rotterdam, The Netherlands
| | - Barbara J Sibbles
- Department of Pediatrics, Erasmus MC, Sophia Children's Hospital, Rotterdam, The Netherlands
| | - René de Coo
- Department of Child Neurology, Erasmus MC, Sophia Children's Hospital, Rotterdam, The Netherlands
| | - Alice Brooks
- Department of Clinical Genetics, Erasmus MC, Sophia Children's Hospital, Rotterdam, The Netherlands
| | - Grazia M S Mancini
- Department of Clinical Genetics, Erasmus MC, Sophia Children's Hospital, Rotterdam, The Netherlands.
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24
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Sudden death in a case of megalencephaly capillary malformation associated with a de novo mutation in AKT3. Childs Nerv Syst 2015; 31:465-71. [PMID: 25416470 DOI: 10.1007/s00381-014-2589-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2014] [Accepted: 11/03/2014] [Indexed: 10/24/2022]
Abstract
INTRODUCTION Megalencephaly capillary malformation (MCAP) is a syndrome involving brain overgrowth, characterized by megalencephaly, capillary malformations, asymmetric growth, polymicrogyria, polydactyly, and syndactyly. Cerebellar tonsillar herniation (CTH) and ventriculomegaly are also observed in over half the patients with this syndrome. Early sudden death has been reported in MCAP, but its causes and the surgical strategies for its prevention remain unclear. CASE REPORT Here, we report on a patient with MCAP who died suddenly at 5 months of age. He presented with progressive macrocephaly and hypotonia. MRI performed at 4 months of age showed tight posterior fossa, bilateral perisylvian polymicrogyria, enlargement of the straight sinus, and a thickened corpus callosum. However, since the patient did not exhibit capillary malformation, polydactyly, or syndactyly, a definitive diagnosis of MCAP could not be made. He died suddenly while asleep at home 1 month later. The sudden death of MCAP patients was previously attributed to CTH, convulsion, or arrhythmia. In this case, progressive cerebellar enlargement appeared to be the underlying cause. After the patient's death, using his preserved DNA, a missense mutation in the AKT3 gene was identified. Vakt murine thymoma viral oncogene homologue (AKT) is a serine-threonine kinase that functions in the mammalian target of rapamycin (mTOR) pathway and plays an important role in cell proliferation. CONCLUSION Accurate early diagnosis, including imaging and genetic analyses, and the recognition and treatment of critical conditions are required to prevent the sudden death of patients with MCAP.
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25
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D'Gama AM, Geng Y, Couto JA, Martin B, Boyle EA, LaCoursiere CM, Hossain A, Hatem NE, Barry BJ, Kwiatkowski DJ, Vinters HV, Barkovich AJ, Shendure J, Mathern GW, Walsh CA, Poduri A. Mammalian target of rapamycin pathway mutations cause hemimegalencephaly and focal cortical dysplasia. Ann Neurol 2015; 77:720-5. [PMID: 25599672 DOI: 10.1002/ana.24357] [Citation(s) in RCA: 205] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Revised: 12/19/2014] [Accepted: 12/24/2014] [Indexed: 12/21/2022]
Abstract
Focal malformations of cortical development, including focal cortical dysplasia (FCD) and hemimegalencephaly (HME), are important causes of intractable childhood epilepsy. Using targeted and exome sequencing on DNA from resected brain samples and nonbrain samples from 53 patients with FCD or HME, we identified pathogenic germline and mosaic mutations in multiple PI3K/AKT pathway genes in 9 patients, and a likely pathogenic variant in 1 additional patient. Our data confirm the association of DEPDC5 with sporadic FCD but also implicate this gene for the first time in HME. Our findings suggest that modulation of the mammalian target of rapamycin pathway may hold promise for malformation-associated epilepsy.
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Affiliation(s)
- Alissa M D'Gama
- Division of Genetics and Genomics, Department of Medicine, Manton Center for Orphan Disease Research and Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA; Departments of Pediatrics and Neurology, Harvard Medical School, Boston, MA; Program in Medical and Population Genetics, Broad Institute of Massachusetts Institute of Technology and Harvard University, Cambridge, MA
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26
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Conti V, Pantaleo M, Barba C, Baroni G, Mei D, Buccoliero AM, Giglio S, Giordano F, Baek ST, Gleeson JG, Guerrini R. Focal dysplasia of the cerebral cortex and infantile spasms associated with somatic 1q21.1-q44 duplication including the AKT3 gene. Clin Genet 2014; 88:241-7. [PMID: 25091978 DOI: 10.1111/cge.12476] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Revised: 07/15/2014] [Accepted: 07/30/2014] [Indexed: 02/01/2023]
Abstract
Somatic and germline duplications or activating mutations of AKT3 have been reported in patients with hemimegalencephaly and megalencephaly. We performed array comparative genomic hybridization on brain tissue and blood in 16 consecutive patients with symptomatic epilepsy due to focal or multilobar malformations of cortical development who underwent surgical treatment of epilepsy. One patient with infantile spasms and a dysplastic left frontal lobe harboured a somatic trisomy of the 1q21.1-q44 chromosomal region, encompassing the AKT3 gene, in the dysplastic brain tissue but not in blood and saliva. Histopathology revealed severe cortical dyslamination, a thin cortex in the premotor area with microgyri and microsulci, immature neurons with disoriented dendrites and areas of cortical heterotopia in the sub-cortical white matter. These cytoarchitectural changes are close to those defining type Ib focal cortical dysplasia. Immunohistochemistry in brain specimens showed hyperactivation of the PI3K/AKT/mTOR pathway. These findings indicate that AKT3 upregulation may cause focal malformations of cortical development. There appears to be an etiologic continuum between hemimegalencephaly and focal cortical dysplastic lesions. The extent of brain malformations due to AKT3 upregulation may be related to the embryonic stage when the post-zygotic gene alteration occurs.
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Affiliation(s)
- V Conti
- Pediatric Neurology and Neurogenetics Unit and Laboratories, A. Meyer Children's Hospital - University of Florence, Florence, Italy
| | - M Pantaleo
- Medical Genetics Unit, A. Meyer Children's Hospital - University of Florence, Florence, Italy
| | - C Barba
- Pediatric Neurology and Neurogenetics Unit and Laboratories, A. Meyer Children's Hospital - University of Florence, Florence, Italy
| | - G Baroni
- Department of Critical Care Medicine and Surgery, University of Florence, Florence, Italy
| | - D Mei
- Pediatric Neurology and Neurogenetics Unit and Laboratories, A. Meyer Children's Hospital - University of Florence, Florence, Italy
| | - A M Buccoliero
- Pathology Unit, A. Meyer Children's Hospital, Florence, Italy
| | - S Giglio
- Medical Genetics Unit, A. Meyer Children's Hospital - University of Florence, Florence, Italy
| | - F Giordano
- Division of Neurosurgery, A. Meyer Children's Hospital, Florence, Italy
| | - S T Baek
- Department of Neurosciences, Howard Hughes Medical Institute, University of California San Diego, La Jolla, CA, USA
| | - J G Gleeson
- Department of Neurosciences, Howard Hughes Medical Institute, University of California San Diego, La Jolla, CA, USA
| | - R Guerrini
- Pediatric Neurology and Neurogenetics Unit and Laboratories, A. Meyer Children's Hospital - University of Florence, Florence, Italy.,Epilepsy and Clinical Neurophysiology Laboratory, IRCCS Stella Maris Foundation, Calambrone, Pisa, Italy
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27
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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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