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Kowkabi S, Yavarian M, Kaboodkhani R, Mohammadi M, Shervin Badv R. PCDH19-clustering epilepsy, pathophysiology and clinical significance. Epilepsy Behav 2024; 154:109730. [PMID: 38521028 DOI: 10.1016/j.yebeh.2024.109730] [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: 01/19/2024] [Revised: 02/07/2024] [Accepted: 02/27/2024] [Indexed: 03/25/2024]
Abstract
PCDH19 clustering epilepsy (PCDH19-CE) is an X-linked epilepsy disorder associated with intellectual disability (ID) and behavioral disturbances, which is caused by PCDH19 gene variants. PCDH19 pathogenic variant leads to epilepsy in heterozygous females, not in hemizygous males and the inheritance pattern is unusual. The hypothesis of cellular interference was described as a key pathogenic mechanism. According to that, males do not develop the disease because of the uniform expression of PCDH19 (variant or wild type) unless they have a somatic variation. We conducted a literature review on PCDH19-CE pathophysiology and concluded that other significant mechanisms could contribute to pathogenesis including: asymmetric cell division and heterochrony, female-related allopregnanolone deficiency, altered steroid gene expression, decreased Gamma-aminobutyric acid receptor A (GABAA) function, and blood-brain barrier (BBB) dysfunction. Being aware of these mechanisms helps us when we should decide which therapeutic option is more suitable for which patient.
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Affiliation(s)
- Safoura Kowkabi
- Child Neurology Division and Children's Epilepsy Monitoring Unit, Children's Medical Centre, Tehran University of Medical Sciences, Tehran, Iran; Shiraz University of Medical Sciences, Shiraz, Iran.
| | - Majid Yavarian
- Hematology Research Center, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran.
| | | | - Mahmood Mohammadi
- Child Neurology Division and Children's Epilepsy Monitoring Unit, Children's Medical Centre, Tehran University of Medical Sciences, Tehran, Iran
| | - Reza Shervin Badv
- Child Neurology Division and Children's Epilepsy Monitoring Unit, Children's Medical Centre, Tehran University of Medical Sciences, Tehran, Iran
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Wang Y, Xiao X, Li X, Yi Z, Jiang Y, Zhang F, Zhou L, Li S, Jia X, Sun W, Wang P, Zhang Q. Genetic and clinical landscape of ARR3-associated MYP26: the most common cause of Mendelian early-onset high myopia with a unique inheritance. Br J Ophthalmol 2023; 107:1545-1553. [PMID: 36180177 PMCID: PMC10579186 DOI: 10.1136/bjo-2022-321511] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Accepted: 07/01/2022] [Indexed: 11/03/2022]
Abstract
AIMS To elucidate genetic background of early-onset high myopia (eoHM) and characteristics of ARR3-associated MYP26. METHODS Variants in 14 genes reported to contribute to eoHM, including ARR3, were selected from exome sequencing data set and classified into different categories following American College of Medical Genetics and Genomics guidelines based on in silico prediction, associated phenotypes, confirmation and cosegregation analysis. The available clinical data of individuals were summarised. RESULTS Pathogenic and likely pathogenic variants in three of 14 genes were identified in 52 of 928 families with eoHM, including 29 in ARR3, 22 in OPN1LW and 1 in LRPAP1. For ARR3, 24 pathogenic variants (16 truncation and 8 missense) were identified in 66 women and 12 men, in whom 64 women and 4 men had eoHM by X-linked female-limited inheritance. Refraction ranged from -5.00 to -28.75 diopter (-12.58±4.83). Mild-to-moderately reduced cone responses were recorded in 76.9% (10/13) of patients with electroretinogram recordings. Most patients (75.9%, 41/54) had mild myopic fundus changes (C0 to C1). Genotype-phenotype analysis suggested that the myopic retinopathy degree was correlated with age and the variant's nature. Peripheral retinal degeneration was observed in 38.5% (5/13) patients using wide-field examinations. CONCLUSION This study reveals ARR3 as the most frequently implicated gene for Mendelian eoHM. Truncations and highly scored missense variants in ARR3 are pathogenic. Myopia due to ARR3 mutations is transmitted in X-linked female-limited inheritance, manifests with mild cone impairment and slowly progresses to pathologic myopia. Identification of the most common cause for Mendelian eoHM provides a valuable starting point into the molecular mechanism of myopia.
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Affiliation(s)
- Yingwei Wang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, Guangdong, China
| | - Xueshan Xiao
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, Guangdong, China
| | - Xueqing Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, Guangdong, China
| | - Zhen Yi
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, Guangdong, China
| | - Yi Jiang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, Guangdong, China
| | - Fengsheng Zhang
- Department of Ophthalmology, Chaoju Inner Mongolia Eye Hospital Co Ltd, Hohhot, China
| | - Lin Zhou
- Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Shiqiang Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, Guangdong, China
| | - Xiaoyun Jia
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, Guangdong, China
| | - Wenmin Sun
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, Guangdong, China
| | - Panfeng Wang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, Guangdong, China
| | - Qingjiong Zhang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, Guangdong, China
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Chen Y, Yang X, Chen J, Yang X, Yang Y, Liu A, Zhang X, Wu W, Sun D, Yang Z, Jiang Y, Zhang Y. PCDH19-related epilepsy in mosaic males: The phenotypic implication of genotype and variant allele frequency. Front Neurol 2022; 13:1041509. [PMID: 36408521 PMCID: PMC9669318 DOI: 10.3389/fneur.2022.1041509] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2022] [Accepted: 10/06/2022] [Indexed: 11/15/2023] Open
Abstract
OBJECTIVE To analyze the genotypes and phenotypes of mosaic male patients with PCDH19-related epilepsy (PCDH19-RE) and explore the correlation between genotype, variant allele frequency (VAF), and phenotypic severity. METHODS Clinical data and peripheral blood samples of 11 male mosaic patients were collected and analyzed in our study. The VAF of the PCDH19 gene from peripheral blood was quantified using amplicon-based deep sequencing. Additional 20 mosaic male patients with PCDH19-RE were collected from the published literature, with 10 patients whose VAFs of the PCDH19 gene were available for analytic purposes. RESULTS In our cohort of 11 patients, 10 variants were identified, and four were novel. The VAF of the PCDH19 gene from peripheral blood ranged from 27 to 90%. The median seizure onset age was 6 months (range: 4-9 months). Clinical manifestations included cluster seizures (100%), fever sensitivity (73%), focal seizures (91%), developmental delay/intellectual disability (DD/ID, 82%), and autistic features (45%). Thirty-one mosaic male patients collected from our cohort and the literature developed seizures mostly (87%) within one year of age. Variant types included missense variants (42%), truncating variants (52%), splice variants (3%), and whole PCDH19 deletion (3%). Among 21 patients with a definite VAF from our cohort and the literature, nine had a low VAF ( ≤ 50%) and 12 had a high VAF (> 50%). Seventy-five percent of variants from the high VAF group were missense, whereas 89% of those from the low VAF group were truncations. The median seizure onset age was 6 months in the low VAF group and 9 months in the high VAF group (p = 0.018). Forty-four percent (4/9) of patients from the low VAF group achieved seizure-free for ≥1 year, whereas none of the 12 patients from the high VAF group did (p = 0.021). DD/ID was present in 83% (10/12) of the high VAF group and 56% (5/9) of the low VAF group (p = 0.331). CONCLUSION The predominant variant types were truncating and missense variants. Missense variants tended to have higher VAFs. Patients with a high VAF were more likely to have a more severe epileptic phenotype. Our findings shed light on the phenotypic implications of VAF in mosaic males with PCDH19-RE.
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Affiliation(s)
- Yi Chen
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Xiaoxu Yang
- Center for Bioinformatics, State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, China
| | - Jiaoyang Chen
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Xiaoling Yang
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Ying Yang
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Aijie Liu
- Department of Pediatric Neurology, Capital Institute of Pediatrics, Beijing, China
| | - Xiaoli Zhang
- Department of Pediatrics, The Third Affiliated Hospital of Zheng Zhou University, Zhengzhou, China
| | - Wenjuan Wu
- Department of Neurology, Hebei Children's Hospital, Shijiazhuang, China
| | - Dan Sun
- Department of Neurology, Wuhan Children's Hospital, Wuhan, China
| | - Zhixian Yang
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Yuwu Jiang
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Yuehua Zhang
- Department of Pediatrics, Peking University First Hospital, Beijing, China
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Right Place at the Right Time: How Changes in Protocadherins Affect Synaptic Connections Contributing to the Etiology of Neurodevelopmental Disorders. Cells 2020; 9:cells9122711. [PMID: 33352832 PMCID: PMC7766791 DOI: 10.3390/cells9122711] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 12/14/2020] [Accepted: 12/15/2020] [Indexed: 11/17/2022] Open
Abstract
During brain development, neurons need to form the correct connections with one another in order to give rise to a functional neuronal circuitry. Mistakes during this process, leading to the formation of improper neuronal connectivity, can result in a number of brain abnormalities and impairments collectively referred to as neurodevelopmental disorders. Cell adhesion molecules (CAMs), present on the cell surface, take part in the neurodevelopmental process regulating migration and recognition of specific cells to form functional neuronal assemblies. Among CAMs, the members of the protocadherin (PCDH) group stand out because they are involved in cell adhesion, neurite initiation and outgrowth, axon pathfinding and fasciculation, and synapse formation and stabilization. Given the critical role of these macromolecules in the major neurodevelopmental processes, it is not surprising that clinical and basic research in the past two decades has identified several PCDH genes as responsible for a large fraction of neurodevelopmental disorders. In the present article, we review these findings with a focus on the non-clustered PCDH sub-group, discussing the proteins implicated in the main neurodevelopmental disorders.
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Trovato F, Parra R, Pracucci E, Landi S, Cozzolino O, Nardi G, Cruciani F, Pillai V, Mosti L, Cwetsch AW, Cancedda L, Gritti L, Sala C, Verpelli C, Maset A, Lodovichi C, Ratto GM. Modelling genetic mosaicism of neurodevelopmental disorders in vivo by a Cre-amplifying fluorescent reporter. Nat Commun 2020; 11:6194. [PMID: 33273479 PMCID: PMC7713426 DOI: 10.1038/s41467-020-19864-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Accepted: 10/27/2020] [Indexed: 12/20/2022] Open
Abstract
Genetic mosaicism, a condition in which an organ includes cells with different genotypes, is frequently present in monogenic diseases of the central nervous system caused by the random inactivation of the X-chromosome, in the case of X-linked pathologies, or by somatic mutations affecting a subset of neurons. The comprehension of the mechanisms of these diseases and of the cell-autonomous effects of specific mutations requires the generation of sparse mosaic models, in which the genotype of each neuron is univocally identified by the expression of a fluorescent protein in vivo. Here, we show a dual-color reporter system that, when expressed in a floxed mouse line for a target gene, leads to the creation of mosaics with tunable degree. We demonstrate the generation of a knockout mosaic of the autism/epilepsy related gene PTEN in which the genotype of each neuron is reliably identified, and the neuronal phenotype is accurately characterized by two-photon microscopy.
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Affiliation(s)
- Francesco Trovato
- National Enterprise for Nanoscience and Nanotechnology (NEST), Istituto Nanoscienze Consiglio Nazionale delle Ricerche (CNR) and Scuola Normale Superiore Pisa, 56127, Pisa, Italy.
| | - Riccardo Parra
- National Enterprise for Nanoscience and Nanotechnology (NEST), Istituto Nanoscienze Consiglio Nazionale delle Ricerche (CNR) and Scuola Normale Superiore Pisa, 56127, Pisa, Italy
| | - Enrico Pracucci
- National Enterprise for Nanoscience and Nanotechnology (NEST), Istituto Nanoscienze Consiglio Nazionale delle Ricerche (CNR) and Scuola Normale Superiore Pisa, 56127, Pisa, Italy
| | - Silvia Landi
- National Enterprise for Nanoscience and Nanotechnology (NEST), Istituto Nanoscienze Consiglio Nazionale delle Ricerche (CNR) and Scuola Normale Superiore Pisa, 56127, Pisa, Italy
- Institute of Neuroscience CNR, Pisa, Italy
| | - Olga Cozzolino
- National Enterprise for Nanoscience and Nanotechnology (NEST), Istituto Nanoscienze Consiglio Nazionale delle Ricerche (CNR) and Scuola Normale Superiore Pisa, 56127, Pisa, Italy
| | - Gabriele Nardi
- National Enterprise for Nanoscience and Nanotechnology (NEST), Istituto Nanoscienze Consiglio Nazionale delle Ricerche (CNR) and Scuola Normale Superiore Pisa, 56127, Pisa, Italy
| | - Federica Cruciani
- National Enterprise for Nanoscience and Nanotechnology (NEST), Istituto Nanoscienze Consiglio Nazionale delle Ricerche (CNR) and Scuola Normale Superiore Pisa, 56127, Pisa, Italy
| | - Vinoshene Pillai
- National Enterprise for Nanoscience and Nanotechnology (NEST), Istituto Nanoscienze Consiglio Nazionale delle Ricerche (CNR) and Scuola Normale Superiore Pisa, 56127, Pisa, Italy
| | - Laura Mosti
- National Enterprise for Nanoscience and Nanotechnology (NEST), Istituto Nanoscienze Consiglio Nazionale delle Ricerche (CNR) and Scuola Normale Superiore Pisa, 56127, Pisa, Italy
| | - Andrzej W Cwetsch
- Istituto Italiano di Tecnologia, Genoa, Italy
- Università degli studi di Genova, Genoa, Italy
| | - Laura Cancedda
- Istituto Italiano di Tecnologia, Genoa, Italy
- Istituto Telethon Dulbecco, Rome, Italy
| | | | - Carlo Sala
- Institute of Neuroscience CNR, Milan, Italy
| | | | - Andrea Maset
- Veneto Institute of Molecular Medicine, Padua, Italy
- Padova Neuroscience Center, Padova Università di Padova, Padua, Italy
| | - Claudia Lodovichi
- Veneto Institute of Molecular Medicine, Padua, Italy
- Padova Neuroscience Center, Padova Università di Padova, Padua, Italy
- Institute of Neuroscience CNR, Padua, Italy
| | - Gian Michele Ratto
- National Enterprise for Nanoscience and Nanotechnology (NEST), Istituto Nanoscienze Consiglio Nazionale delle Ricerche (CNR) and Scuola Normale Superiore Pisa, 56127, Pisa, Italy.
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Kozina AA, Okuneva EG, Baryshnikova NV, Fedonyuk ID, Kholin AA, Il'ina ES, Krasnenko AY, Stetsenko IF, Plotnikov NA, Klimchuk OI, Surkova EI, Ilinsky VV. Two novel PCDH19 mutations in Russian patients with epilepsy with intellectual disability limited to females: a case report. BMC MEDICAL GENETICS 2020; 21:209. [PMID: 33087045 PMCID: PMC7579871 DOI: 10.1186/s12881-020-01119-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Accepted: 09/03/2020] [Indexed: 11/16/2022]
Abstract
Background Epilepsy with intellectual disability limited to females (Epileptic encephalopathy, early infantile, 9; EIEE9) is a rare early infantile epileptic encephalopathy characterized by an unusual X-linked inheritance: females with heterozygous mutations are affected, while hemizygous males are not. Case presentation We describe the clinical and molecular characteristics of 2 Russian patients with EIEE9 (females, ages 3 years and 7 years). In these patients seizures developed at the age of 3 years. Additionally, for our patients and for cases described in the literature we searched for a possible relationship between the type and localization of the mutation and the EIEE9 clinical phenotype. Conclusions We identified two novel PCDH19 mutations in EIEE9 patients: a missense mutation in exon 1 (c.1236C > A, p.Asp412Glu) and a frameshift in exon 3 (c.2386_2387insGTCT, p.Thr796fs). We conclude that the age of seizure onset and the presence of intellectual disability may depend not on the type and localization of PCDH19 mutations, but on the X-inactivation status. The study also highlights the need to screen for EIEE9 among young female epilepsy patients.
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Affiliation(s)
- Anastasiya Aleksandrovna Kozina
- Institute of Biomedical Chemistry, Pogodinskaya street 10/8, 119121, Moscow, Russia.,Pirogov Russian National Research Medical University, Ostrovitianova street 1, 117997, Moscow, Russia
| | | | - Natalia Vladimirovna Baryshnikova
- Pirogov Russian National Research Medical University, Ostrovitianova street 1, 117997, Moscow, Russia.,Genotek Ltd., Nastavnicheskii pereulok 17/1, 105120, Moscow, Russia
| | - Inessa Dmitrievna Fedonyuk
- Russian Children's Clinical Hospital of Pirogov Russian National Research Medical University, Leniskiy prospekt 117, 117513, Moscow, Russia
| | - Alexey Aleksandrovich Kholin
- Pirogov Russian National Research Medical University, Ostrovitianova street 1, 117997, Moscow, Russia.,Russian Children's Clinical Hospital of Pirogov Russian National Research Medical University, Leniskiy prospekt 117, 117513, Moscow, Russia
| | - Elena Stepanovna Il'ina
- Russian Children's Clinical Hospital of Pirogov Russian National Research Medical University, Leniskiy prospekt 117, 117513, Moscow, Russia
| | | | | | | | | | | | - Valery Vladimirovich Ilinsky
- Institute of Biomedical Chemistry, Pogodinskaya street 10/8, 119121, Moscow, Russia.,Pirogov Russian National Research Medical University, Ostrovitianova street 1, 117997, Moscow, Russia.,Genotek Ltd., Nastavnicheskii pereulok 17/1, 105120, Moscow, Russia.,Vavilov Institute of General Genetics, Gubkina street 3, 119333, Moscow, Russia
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Yang X, Chen J, Zheng B, Liu X, Cao Z, Wang X. PCDH19-Related Epilepsy in Early Onset of Chinese Male Patient: Case Report and Literature Review. Front Neurol 2020; 11:311. [PMID: 32425876 PMCID: PMC7203462 DOI: 10.3389/fneur.2020.00311] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2019] [Accepted: 03/31/2020] [Indexed: 11/29/2022] Open
Abstract
Mutations in PCDH19 are associated with epilepsy, intellectual disability and behavioral disturbances, mostly related to females. The unique X-linked pattern of inheritance affects females predominantly, while usually is transmitted through asymptomatic males. Recently, new research has demonstrated that males with a mosaic pattern of inheritance could also be affected. As yet, PCDH19 mutations have been reported in hundreds of females; however, only 15 mosaic males were reported to exhibit epileptic seizures with the onset ranges between 6 and 31 months. These patients were usually reported to carry various mutations in the PCDH19. Here we describe a non-sense variant at the PCDH19 (c.498C>G; p.Y166*) in the Chinese male that exhibited early developmental delay and frequent seizures starting from the age of 5 months. We aim that this case report, focusing on studying clinical seizures, therapeutic approaches, and the patient's prognosis, will contribute to the cumulative knowledge of this rare and complex genetic disorder.
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Affiliation(s)
- Xiao Yang
- Department of Neurology, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Jing Chen
- Department of Neurology, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - BiXia Zheng
- Department of Neurology, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Xianyu Liu
- Department of Neurology, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Zixuan Cao
- Department of Neurology, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Xiaoyu Wang
- Department of Neurology, Children's Hospital of Nanjing Medical University, Nanjing, China
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Niazi R, Fanning EA, Depienne C, Sarmady M, Abou Tayoun AN. A mutation update for the PCDH19 gene causing early-onset epilepsy in females with an unusual expression pattern. Hum Mutat 2019; 40:243-257. [PMID: 30582250 DOI: 10.1002/humu.23701] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Revised: 11/26/2018] [Accepted: 12/18/2018] [Indexed: 11/08/2022]
Abstract
The PCDH19 gene consists of six exons encoding a 1,148 amino acid transmembrane protein, Protocadherin 19, which is involved in brain development. Heterozygous pathogenic variants in this gene are inherited in an unusual X-linked dominant pattern in which heterozygous females are affected, while hemizygous males are typically unaffected, although they pass on the pathogenic variant to each affected daughter. PCDH19-related disorder is known to cause early-onset epilepsy in females characterized by seizure clusters exacerbated by fever and in most cases, onset is within the first year of life. This condition was initially described in 1971 and in 2008 PCDH19 was identified as the underlying genetic etiology. This condition is the result of pathogenic loss-of-function variants that may be de novo or inherited from an affected mother or unaffected father and cellular interference has been hypothesized to be the culprit. Heterozygous females are symptomatic because of the presence of both wild-type and mutant cells that interfere with one another due to the production of different surface proteins, whereas nonmosaic hemizygous males produce a homogenous population of cells. Here, we review novel pathogenic variants in the PCDH19 gene since 2012 to date, and summarize any genotype-phenotype correlations.
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Affiliation(s)
- Rojeen Niazi
- Division of Genomic Diagnostics, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - Elizabeth A Fanning
- Division of Genomic Diagnostics, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - Christel Depienne
- Institute of Human Genetics, University Hospital Essen, University Duisburg-Essen, Essen, Germany.,Inserm U 1127, CNRS UMR 7225, Sorbonne Universités, UPMC Univ Paris, 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière, Paris, France.,IGBMC, CNRS UMR 7104/INSERM U964/Université de Strasbourg, Illkirch, France
| | - Mahdi Sarmady
- Division of Genomic Diagnostics, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania.,The University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania
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