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Veltra D, Theodorou V, Katsalouli M, Vorgia P, Niotakis G, Tsaprouni T, Pons R, Kosma K, Kampouraki A, Tsoutsou I, Makrythanasis P, Kekou K, Traeger-Synodinos J, Sofocleous C. SCN1A Channels a Wide Range of Epileptic Phenotypes: Report of Novel and Known Variants with Variable Presentations. Int J Mol Sci 2024; 25:5644. [PMID: 38891831 PMCID: PMC11171476 DOI: 10.3390/ijms25115644] [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: 04/03/2024] [Revised: 05/15/2024] [Accepted: 05/18/2024] [Indexed: 06/21/2024] Open
Abstract
SCN1A, the gene encoding for the Nav1.1 channel, exhibits dominant interneuron-specific expression, whereby variants disrupting the channel's function affect the initiation and propagation of action potentials and neuronal excitability causing various types of epilepsy. Dravet syndrome (DS), the first described clinical presentation of SCN1A channelopathy, is characterized by severe myoclonic epilepsy in infancy (SMEI). Variants' characteristics and other genetic or epigenetic factors lead to extreme clinical heterogeneity, ranging from non-epileptic conditions to developmental and epileptic encephalopathy (DEE). This current study reports on findings from 343 patients referred by physicians in hospitals and tertiary care centers in Greece between 2017 and 2023. Positive family history for specific neurologic disorders was disclosed in 89 cases and the one common clinical feature was the onset of seizures, at a mean age of 17 months (range from birth to 15 years old). Most patients were specifically referred for SCN1A investigation (Sanger Sequencing and MLPA) and only five for next generation sequencing. Twenty-six SCN1A variants were detected, including nine novel causative variants (c.4567A>Τ, c.5564C>A, c.2176+2T>C, c.3646G>C, c.4331C>A, c.1130_1131delGAinsAC, c.1574_1580delCTGAGGA, c.4620A>G and c.5462A>C), and are herein presented, along with subsequent genotype-phenotype associations. The identification of novel variants complements SCN1A databases extending our expertise on genetic counseling and patient and family management including gene-based personalized interventions.
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Affiliation(s)
- Danai Veltra
- Laboratory of Medical Genetics, Medical School, National and Kapodistrian University of Athens, St. Sophia’s Children’s Hospital, 11527 Athens, Greece; (D.V.); (K.K.); (A.K.); (I.T.); (P.M.); (K.K.); (J.T.-S.)
- Research University Institute for the Study and Prevention of Genetic and Malignant Disease of Childhood, National and Kapodistrian University of Athens, St. Sophia’s Children’s Hospital, 11527 Athens, Greece
| | - Virginia Theodorou
- Pediatric Neurology Department, St. Sophia’s Children’s Hospital, 11527 Athens, Greece; (V.T.); (M.K.)
| | - Marina Katsalouli
- Pediatric Neurology Department, St. Sophia’s Children’s Hospital, 11527 Athens, Greece; (V.T.); (M.K.)
| | - Pelagia Vorgia
- Agrifood and Life Sciences Institute, Hellenic Mediterranean University, 71410 Heraklion, Greece;
| | - Georgios Niotakis
- Pediatric Neurology Department, Venizelion Hospital, 71409 Heraklion, Greece;
| | | | - Roser Pons
- First Department of Pediatrics, Medical School, National and Kapodistrian University of Athens, St. Sophia’s Children’s Hospital, 11527 Athens, Greece;
| | - Konstantina Kosma
- Laboratory of Medical Genetics, Medical School, National and Kapodistrian University of Athens, St. Sophia’s Children’s Hospital, 11527 Athens, Greece; (D.V.); (K.K.); (A.K.); (I.T.); (P.M.); (K.K.); (J.T.-S.)
| | - Afroditi Kampouraki
- Laboratory of Medical Genetics, Medical School, National and Kapodistrian University of Athens, St. Sophia’s Children’s Hospital, 11527 Athens, Greece; (D.V.); (K.K.); (A.K.); (I.T.); (P.M.); (K.K.); (J.T.-S.)
| | - Irene Tsoutsou
- Laboratory of Medical Genetics, Medical School, National and Kapodistrian University of Athens, St. Sophia’s Children’s Hospital, 11527 Athens, Greece; (D.V.); (K.K.); (A.K.); (I.T.); (P.M.); (K.K.); (J.T.-S.)
| | - Periklis Makrythanasis
- Laboratory of Medical Genetics, Medical School, National and Kapodistrian University of Athens, St. Sophia’s Children’s Hospital, 11527 Athens, Greece; (D.V.); (K.K.); (A.K.); (I.T.); (P.M.); (K.K.); (J.T.-S.)
- Department of Genetic Medicine and Development, Medical School, University of Geneva, 1211 Geneva, Switzerland
- Biomedical Research Foundation of the Academy of Athens, 11527 Athens, Greece
| | - Kyriaki Kekou
- Laboratory of Medical Genetics, Medical School, National and Kapodistrian University of Athens, St. Sophia’s Children’s Hospital, 11527 Athens, Greece; (D.V.); (K.K.); (A.K.); (I.T.); (P.M.); (K.K.); (J.T.-S.)
| | - Joanne Traeger-Synodinos
- Laboratory of Medical Genetics, Medical School, National and Kapodistrian University of Athens, St. Sophia’s Children’s Hospital, 11527 Athens, Greece; (D.V.); (K.K.); (A.K.); (I.T.); (P.M.); (K.K.); (J.T.-S.)
| | - Christalena Sofocleous
- Laboratory of Medical Genetics, Medical School, National and Kapodistrian University of Athens, St. Sophia’s Children’s Hospital, 11527 Athens, Greece; (D.V.); (K.K.); (A.K.); (I.T.); (P.M.); (K.K.); (J.T.-S.)
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Lecoquierre F, Cassinari K, Drouot N, May A, Fourneaux S, Charbonnier F, Derambure C, Coutant S, Saugier-Veber P, Hoischen A, Charbonnier C, Nicolas G. Assessment of parental mosaicism rates in neurodevelopmental disorders caused by apparent de novo pathogenic variants using deep sequencing. Sci Rep 2024; 14:5289. [PMID: 38438430 PMCID: PMC10912112 DOI: 10.1038/s41598-024-53358-9] [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: 11/28/2023] [Accepted: 01/31/2024] [Indexed: 03/06/2024] Open
Abstract
While de novo variants (DNV) are overall at low risk of recurrence in subsequent pregnancies, a subset is at high risk due to parental mosaicism. Accurately identifying cases of parental mosaicism is therefore important for genetic counseling in clinical care. Some studies have investigated the rate of parental mosaics, but most were either limited by the sensitivity of the techniques (i.e. exome or genome sequencing), or focused on specific types of disease such as epileptic syndromes. This study aimed to determine the proportion of parental mosaicism among the DNV causing neurodevelopmental disorders (NDDs) in a series not enriched in epilepsy syndromes. We collected 189 patients with NDD-associated DNV. We applied a smMIP enrichment method and sequenced parental blood DNA samples to an average depth of 7000x. Power simulation indicated that mosaicism with an allelic fraction of 0.5% would have been detected for 87% of positions with 90% power. We observed seven parental mosaic variants (3.7% of families), of which four (2.1% of families) had an allelic fraction of less than 1%. In total, our study identifies a relatively low proportion of parental mosaicism in NDD-associated DNVs and raises the question of a biological mechanism behind the higher rates of parental mosaicism detected in other studies, particularly those focusing on epileptic syndromes.
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Affiliation(s)
- François Lecoquierre
- Univ Rouen Normandie, Inserm U1245 and CHU Rouen, Department of Genetics and reference center for developmental disorders, F-76000, Rouen, France.
- Centre de Ressources Biologiques institutionnel du CHU de Rouen - Biothèque filière génétique, Rouen, France.
| | - Kévin Cassinari
- Univ Rouen Normandie, Inserm U1245 and CHU Rouen, Department of Genetics and reference center for developmental disorders, F-76000, Rouen, France
| | - Nathalie Drouot
- Univ Rouen Normandie, Inserm U1245 and CHU Rouen, Department of Genetics and reference center for developmental disorders, F-76000, Rouen, France
| | - Angèle May
- Univ Rouen Normandie, Inserm U1245 and CHU Rouen, Department of Genetics and reference center for developmental disorders, F-76000, Rouen, France
| | - Steeve Fourneaux
- Univ Rouen Normandie, Inserm U1245 and CHU Rouen, Department of Genetics and reference center for developmental disorders, F-76000, Rouen, France
| | - Francoise Charbonnier
- Univ Rouen Normandie, Inserm U1245 and CHU Rouen, Department of Genetics and reference center for developmental disorders, F-76000, Rouen, France
| | - Celine Derambure
- Univ Rouen Normandie, Inserm U1245 and CHU Rouen, Department of Genetics and reference center for developmental disorders, F-76000, Rouen, France
| | - Sophie Coutant
- Univ Rouen Normandie, Inserm U1245 and CHU Rouen, Department of Genetics and reference center for developmental disorders, F-76000, Rouen, France
| | - Pascale Saugier-Veber
- Univ Rouen Normandie, Inserm U1245 and CHU Rouen, Department of Genetics and reference center for developmental disorders, F-76000, Rouen, France
| | - Alexander Hoischen
- Department of Human Genetics, Radboud University Medical Center, 6525 GA, Nijmegen, The Netherlands
| | - Camille Charbonnier
- Univ Rouen Normandie, Inserm U1245 and CHU Rouen, Department of Genetics and reference center for developmental disorders, F-76000, Rouen, France
| | - Gaël Nicolas
- Univ Rouen Normandie, Inserm U1245 and CHU Rouen, Department of Genetics and reference center for developmental disorders, F-76000, Rouen, France
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3
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Wirrell EC, Riney K, Specchio N, Zuberi SM. How have the recent updated epilepsy classifications impacted on diagnosis and treatment? Expert Rev Neurother 2023; 23:969-980. [PMID: 37676056 DOI: 10.1080/14737175.2023.2254937] [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: 07/19/2023] [Accepted: 08/30/2023] [Indexed: 09/08/2023]
Abstract
INTRODUCTION Epilepsies are a diverse group of disorders which differ regarding prognosis for seizure control and associated comorbidities. Accurate classification is critical to choose the highest yield investigations and best therapeutic options and to provide the most accurate prognoses regarding the expected degree of seizure control, possible remission, and risk of associated comorbidities to patients and their families. This article reviews the recent updates in epilepsy classification to illustrate how accurate classification impacts care for persons with epilepsy. AREAS COVERED The authors discuss the ILAE 2017 Classification of the Epilepsies along with the modification of the classification for neonatal seizures and epilepsies. They also discuss the ILAE position papers on Epilepsy syndromes in neonates and infants and children of variable age and the Idiopathic Generalized Epilepsies. EXPERT OPINION Accurate epilepsy classification allows selection of the highest yield investigations, choice of optimal therapies, and accurate prognostication of seizures (likelihood of response to antiseizure treatments and likelihood of remission with age), as well as comorbidities (likelihood, type, and severity). As we move into the era of disease modifying therapy, early accurate identification of underlying causes with timely introduction of specific treatments will be crucial to lessen the severity of epilepsy, with improved seizure control and attenuation of associated comorbidities.
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Affiliation(s)
- Elaine C Wirrell
- Divisions of Child and Adolescent Neurology and Epilepsy, Department of Neurology, Mayo Clinic, Rochester, MN, USA
| | - Kate Riney
- Neurosciences Unit, Queensland Children's Hospital, Australia and Faculty of Medicine, University of St Lucia, Brisbane, Queensland, Australia
| | - Nicola Specchio
- Clinical and Experimental Neurology, Bambino Gesu Children's Hospital, IRCCS, Full Member of European Reference Network on Rare and Complex Epilepsies (EpiCARE), Rome, Italy
| | - Sameer M Zuberi
- School of Health and Wellbeing, University of Glasgow, Glasgow, UK
- Royal Hospital for Children, Glasgow, UK
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Li X, Huang S, Wang G, Kang D, Han M, Wu X, Yang J, Zheng Q, Zhao C, Yuan Y, Dai P. Quantitative assessment of low-level parental mosaicism of SNVs and CNVs in Waardenburg syndrome. Hum Genet 2023; 142:419-430. [PMID: 36576601 DOI: 10.1007/s00439-022-02517-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 12/19/2022] [Indexed: 12/29/2022]
Abstract
Waardenburg syndrome (WS) is a rare inherited autosomal dominant disorder caused by SOX10, PAX3, MITF, EDNRB, EDN3, and SNAI2. A large burden of pathogenic de novo variants is present in patients with WS, which may be derived from parental mosaicism. Previously, we retrospectively analyzed 90 WS probands with family information. And the frequency of de novo events and parental mosaicism was preliminary investigated in our previous study. In this study, we further explored the occurrence of low-level parental mosaicism in 33 WS families with de novo variants and introduced our procedure of quantifying low-level mosaicism. Mosaic single nucleotide polymorphisms (SNPs) were validated by amplicon-based next-generation sequencing (NGS); copy-number variants (CNVs) were validated by droplet-digital polymerase chain reaction (ddPCR). Molecular validation of low-level mosaicism of WS-causing variants was performed in four families (12.1%, 4/33). These four mosaic variants, comprising three SNVs and one CNV, were identified in SOX10. The rate of parental mosaicism was 25% (4/16) in WS families with de novo SOX10 variants. The lowest allele ratio of a mosaic variant was 2.0% in parental saliva. These de novo WS cases were explained by parental mosaicism conferring an elevated recurrence risk in subsequent pregnancies of parents. Considering its importance in genetic counseling, low-level parental mosaicism should be systematically investigated by personalized sensitive testing. Amplicon-based NGS and ddPCR are recommended to detect and precisely quantify the mosaicism for SNPs and CNVs.
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Affiliation(s)
- Xiaohong Li
- College of Otolaryngology Head and Neck Surgery, Key Lab of Hearing Impairment Science of Ministry of Education, Key Lab of Hearing Impairment Prevention and Treatment of Beijing, The Sixth Medical Center of Chinese PLA General Hospital, Chinese PLA Medical School, National Clinical Research Center for Otolaryngologic Diseases, #28 Fuxing Road, Beijing, 100853, China.,Department of Otorhinolaryngology Head and Neck Surgery, Key Laboratory for Pediatric Diseases of Otolaryngology-Head and Neck Surgery, National Center for Children's Health, Beijing Children's Hospital, Capital Medical University, Beijing, China
| | - Shasha Huang
- College of Otolaryngology Head and Neck Surgery, Key Lab of Hearing Impairment Science of Ministry of Education, Key Lab of Hearing Impairment Prevention and Treatment of Beijing, The Sixth Medical Center of Chinese PLA General Hospital, Chinese PLA Medical School, National Clinical Research Center for Otolaryngologic Diseases, #28 Fuxing Road, Beijing, 100853, China
| | - Guojian Wang
- College of Otolaryngology Head and Neck Surgery, Key Lab of Hearing Impairment Science of Ministry of Education, Key Lab of Hearing Impairment Prevention and Treatment of Beijing, The Sixth Medical Center of Chinese PLA General Hospital, Chinese PLA Medical School, National Clinical Research Center for Otolaryngologic Diseases, #28 Fuxing Road, Beijing, 100853, China
| | - Dongyang Kang
- College of Otolaryngology Head and Neck Surgery, Key Lab of Hearing Impairment Science of Ministry of Education, Key Lab of Hearing Impairment Prevention and Treatment of Beijing, The Sixth Medical Center of Chinese PLA General Hospital, Chinese PLA Medical School, National Clinical Research Center for Otolaryngologic Diseases, #28 Fuxing Road, Beijing, 100853, China
| | - Mingyu Han
- College of Otolaryngology Head and Neck Surgery, Key Lab of Hearing Impairment Science of Ministry of Education, Key Lab of Hearing Impairment Prevention and Treatment of Beijing, The Sixth Medical Center of Chinese PLA General Hospital, Chinese PLA Medical School, National Clinical Research Center for Otolaryngologic Diseases, #28 Fuxing Road, Beijing, 100853, China
| | - Xiedong Wu
- College of Otolaryngology Head and Neck Surgery, Key Lab of Hearing Impairment Science of Ministry of Education, Key Lab of Hearing Impairment Prevention and Treatment of Beijing, The Sixth Medical Center of Chinese PLA General Hospital, Chinese PLA Medical School, National Clinical Research Center for Otolaryngologic Diseases, #28 Fuxing Road, Beijing, 100853, China
| | - Jinyuan Yang
- College of Otolaryngology Head and Neck Surgery, Key Lab of Hearing Impairment Science of Ministry of Education, Key Lab of Hearing Impairment Prevention and Treatment of Beijing, The Sixth Medical Center of Chinese PLA General Hospital, Chinese PLA Medical School, National Clinical Research Center for Otolaryngologic Diseases, #28 Fuxing Road, Beijing, 100853, China
| | - Qiuchen Zheng
- College of Otolaryngology Head and Neck Surgery, Key Lab of Hearing Impairment Science of Ministry of Education, Key Lab of Hearing Impairment Prevention and Treatment of Beijing, The Sixth Medical Center of Chinese PLA General Hospital, Chinese PLA Medical School, National Clinical Research Center for Otolaryngologic Diseases, #28 Fuxing Road, Beijing, 100853, China
| | - Chaoyue Zhao
- College of Otolaryngology Head and Neck Surgery, Key Lab of Hearing Impairment Science of Ministry of Education, Key Lab of Hearing Impairment Prevention and Treatment of Beijing, The Sixth Medical Center of Chinese PLA General Hospital, Chinese PLA Medical School, National Clinical Research Center for Otolaryngologic Diseases, #28 Fuxing Road, Beijing, 100853, China
| | - Yongyi Yuan
- College of Otolaryngology Head and Neck Surgery, Key Lab of Hearing Impairment Science of Ministry of Education, Key Lab of Hearing Impairment Prevention and Treatment of Beijing, The Sixth Medical Center of Chinese PLA General Hospital, Chinese PLA Medical School, National Clinical Research Center for Otolaryngologic Diseases, #28 Fuxing Road, Beijing, 100853, China.
| | - Pu Dai
- College of Otolaryngology Head and Neck Surgery, Key Lab of Hearing Impairment Science of Ministry of Education, Key Lab of Hearing Impairment Prevention and Treatment of Beijing, The Sixth Medical Center of Chinese PLA General Hospital, Chinese PLA Medical School, National Clinical Research Center for Otolaryngologic Diseases, #28 Fuxing Road, Beijing, 100853, China.
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5
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Krey I, Platzer K, Esterhuizen A, Berkovic SF, Helbig I, Hildebrand MS, Lerche H, Lowenstein D, Møller RS, Poduri A, Sadleir L, Sisodiya SM, Weckhuysen S, Wilmshurst JM, Weber Y, Lemke JR. Current practice in diagnostic genetic testing of the epilepsies. Epileptic Disord 2022; 24:765-786. [PMID: 35830287 PMCID: PMC10752379 DOI: 10.1684/epd.2022.1448] [Citation(s) in RCA: 34] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 05/10/2022] [Indexed: 01/19/2023]
Abstract
Epilepsy genetics is a rapidly developing field, in which novel disease-associated genes, novel mechanisms associated with epilepsy, and precision medicine approaches are continuously being identified. In the past decade, advances in genomic knowledge and analysis platforms have begun to make clinical genetic testing accessible for, in principle, people of all ages with epilepsy. For this reason, the Genetics Commission of the International League Against Epilepsy (ILAE) presents this update on clinical genetic testing practice, including current techniques, indications, yield of genetic testing, recommendations for pre- and post-test counseling, and follow-up after genetic testing is completed. We acknowledge that the resources vary across different settings but highlight that genetic diagnostic testing for epilepsy should be prioritized when the likelihood of an informative finding is high. Results of genetic testing, in particular the identification of causative genetic variants, are likely to improve individual care. We emphasize the importance of genetic testing for individuals with epilepsy as we enter the era of precision therapy.
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Affiliation(s)
- Ilona Krey
- Institute of Human Genetics, University of Leipzig Medical Center, Leipzig, Germany
| | - Konrad Platzer
- Institute of Human Genetics, University of Leipzig Medical Center, Leipzig, Germany
| | - Alina Esterhuizen
- Division of Human Genetics, Department of Pathology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
- National Health Laboratory Service, Groote Schuur Hospital, Cape Town, South Africa
| | - Samuel F. Berkovic
- Epilepsy Research Centre, Department of Medicine, University of Melbourne (Austin Health), Heidelberg, VIC, Australia
| | - Ingo Helbig
- Institute of Clinical Molecular Biology, Christian-Albrechts-University of Kiel, Kiel, Germany
- Department of Neuropediatrics, University Medical Center Schleswig-Holstein, Christian-Albrechts-University, Building C, Arnold-Heller-Straße 3, 24105 Kiel, Germany
- Division of Neurology, Children’s Hospital of Philadelphia, Philadelphia, 3401 Civic Center Blvd, Philadelphia, PA 19104, USA
- The Epilepsy NeuroGenetics Initiative (ENGIN), Children’s Hospital of Philadelphia, Philadelphia, 3401 Civic Center Blvd, Philadelphia, PA 19104, USA
- Department of Biomedical and Health Informatics (DBHi), Children’s Hospital of Philadelphia, Philadelphia, PA, 19104 USA
- Department of Neurology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, 19104 USA
| | - Michael S. Hildebrand
- Epilepsy Research Centre, Department of Medicine, The University of Melbourne, Austin Health, Heidelberg and Murdoch Children’s Research Institute, Royal Children’s Hospital, Victoria, Australia
| | - Holger Lerche
- Department of Epileptology and Neurology, Hertie Institute for Clinical Brain Research, University of Tübingen, Germany
| | - Daniel Lowenstein
- Department of Neurology, University of California, San Francisco, USA
| | - Rikke S. Møller
- Department of Epilepsy Genetics and Personalized Medicine, Danish Epilepsy Centre, Dianalund, Denmark
- Institute for Regional Health Services, University of Southern Denmark, Odense, Denmark
| | - Annapurna Poduri
- Epilepsy Genetics Program, Department of Neurology, Boston Children’s Hospital, Harvard Medical School, Boston, MA, USA
| | - Lynette Sadleir
- Department of Paediatrics and Child Health, University of Otago, Wellington, New Zealand
| | - Sanjay M. Sisodiya
- Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology London, UK and Chalfont Centre for Epilepsy, Buckinghamshire, UK
| | - Sarah Weckhuysen
- Center for Molecular Neurology, VIB-University of Antwerp, VIB, Antwerp, Belgium; Department of Neurology, University Hospital Antwerp, Antwerp, Belgium
| | - Jo M. Wilmshurst
- Department of Paediatric Neurology, Paediatric and Child Health, Red Cross War Memorial Children’s Hospital, Neuroscience Institute, University of Cape Town, South Africa
| | - Yvonne Weber
- Department of Epileptology and Neurology, Hertie Institute for Clinical Brain Research, University of Tübingen, Germany
- Department of Epileptology and Neurology, University of Aachen, Germany
| | - Johannes R. Lemke
- Institute of Human Genetics, University of Leipzig Medical Center, Leipzig, Germany
- Center for Rare Diseases, University of Leipzig Medical Center, Leipzig, Germany
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6
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Frisk S, Wachtmeister A, Laurell T, Lindstrand A, Jäntti N, Malmgren H, Lagerstedt-Robinson K, Tesi B, Taylan F, Nordgren A. Detection of germline mosaicism in fathers of children with intellectual disability syndromes caused by de novo variants. Mol Genet Genomic Med 2022; 10:e1880. [PMID: 35118825 PMCID: PMC9000944 DOI: 10.1002/mgg3.1880] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Revised: 12/21/2021] [Accepted: 01/14/2022] [Indexed: 12/03/2022] Open
Abstract
Background De novo variants are a common cause to rare intellectual disability syndromes, associated with low recurrence risk. However, when such variants occur pre‐zygotically in parental germ cells, the recurrence risk might be higher. Still, the recurrence risk estimates are mainly based on empirical data and the prevalence of germline mosaicism is often unknown. Methods To establish the prevalence of mosaicism in parents of children with intellectual disability syndromes caused by de novo variants, we performed droplet digital PCR on DNA extracted from blood (43 trios), and sperm (31 fathers). Results We detected low‐level mosaicism in sperm‐derived DNA but not in blood in the father of a child with Kleefstra syndrome caused by an EHMT1 variant. Additionally, we found a higher level of paternal mosaicism in sperm compared to blood in the father of a child with Gillespie syndrome caused by an ITPR1 variant. Conclusion By employing droplet digital PCR, we detected paternal germline mosaicism in two intellectual disability syndromes. In both cases, the mosaicism level was higher in sperm than blood, indicating that analysis of blood alone may underestimate germline mosaicism. Therefore, sperm analysis can be clinically useful to establish the recurrence risk for parents and improve genetic counselling.
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Affiliation(s)
- Sofia Frisk
- Department of Molecular Medicine and Surgery, Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden.,Department of Clinical Genetics, Karolinska University Laboratory, Karolinska University Hospital, Stockholm, Sweden
| | - Alexandra Wachtmeister
- Department of Molecular Medicine and Surgery, Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Tobias Laurell
- Department of Molecular Medicine and Surgery, Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden.,Department of Hand Surgery, Södersjukhuset, Stockholm, Sweden
| | - Anna Lindstrand
- Department of Molecular Medicine and Surgery, Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden.,Department of Clinical Genetics, Karolinska University Laboratory, Karolinska University Hospital, Stockholm, Sweden
| | - Nina Jäntti
- Department of Molecular Medicine and Surgery, Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden.,Department of Clinical Genetics, Karolinska University Laboratory, Karolinska University Hospital, Stockholm, Sweden
| | - Helena Malmgren
- Department of Molecular Medicine and Surgery, Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden.,Department of Clinical Genetics, Karolinska University Laboratory, Karolinska University Hospital, Stockholm, Sweden
| | - Kristina Lagerstedt-Robinson
- Department of Molecular Medicine and Surgery, Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden.,Department of Clinical Genetics, Karolinska University Laboratory, Karolinska University Hospital, Stockholm, Sweden
| | - Bianca Tesi
- Department of Molecular Medicine and Surgery, Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden.,Department of Clinical Genetics, Karolinska University Laboratory, Karolinska University Hospital, Stockholm, Sweden
| | - Fulya Taylan
- Department of Molecular Medicine and Surgery, Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden.,Department of Clinical Genetics, Karolinska University Laboratory, Karolinska University Hospital, Stockholm, Sweden
| | - Ann Nordgren
- Department of Molecular Medicine and Surgery, Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden.,Department of Clinical Genetics, Karolinska University Laboratory, Karolinska University Hospital, Stockholm, Sweden
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Abstract
Advances in genetic technology have decreased the cost and increased the accessibility of genetic testing, and introduced new therapeutic options for many genetic conditions. With new treatments available for previously untreatable neurogenetic conditions, identifying a genetic diagnosis has become of great importance. This article provides a review of basic genetic concepts, ethical and counseling considerations with genetic testing, and genetic testing strategies, and highlights a series of clinical care pearls.
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Affiliation(s)
- Roa Sadat
- Pediatric Neurogenetics Clinic, Blue Bird Circle Clinic for Pediatric Neurology, Section of Pediatric Neurology and Developmental Neuroscience, Texas Children's Hospital
- Baylor College of Medicine, 6701 Fannin St., Suite 1250.07, Houston, TX 77030, USA.
| | - Lisa Emrick
- Pediatric Neurogenetics Clinic, Blue Bird Circle Clinic for Pediatric Neurology, Section of Pediatric Neurology and Developmental Neuroscience, Texas Children's Hospital
- Baylor College of Medicine, Houston, TX, USA
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8
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Shu L, Zhang Q, Tian Q, Yang S, Peng X, Mao X, Yang L, Du J, Wang H. Parental mosaicism in de novo neurodevelopmental diseases. Am J Med Genet A 2021; 185:2119-2125. [PMID: 33851778 DOI: 10.1002/ajmg.a.62174] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 01/28/2021] [Accepted: 02/26/2021] [Indexed: 11/12/2022]
Abstract
Neurodevelopmental diseases are increasingly recognized to be caused by "de novo" variants with the expanding use of next-generation sequencing. The apparent de novo variants may actually be low-level hereditary parental mosaic variants, which could increase the recurrence risk of disease by >50% and is thought to be an underappreciated cause of neurodevelopmental diseases. Our study aimed to investigate the frequency of parental mosaicism in "de novo" neurodevelopmental diseases. A total of 237 patients (and parents) with neurodevelopmental diseases carrying apparent de novo pathogenic or likely pathogenic variants were recruited consecutively. Deep next-generation sequencing was performed on parental samples to identify parental mosaicism. Fourteen parental disease-causing mosaicism variants (3.0%) in 11 genes were detected with alternate allele frequency (AAF) 0.22%-34%. Three parents showed milder clinical phenotypes than their offspring with relatively high AAF (23.33%, 25%, 34% separately). One recurrent variant was identified prenatally. A review of cohort study on parental mosaicism in neurodevelopmental diseases was performed. Our study highlights that identifying the parental mosaic disease-causing variants especially the low-level mosaicism will contribute to improving the accuracy of genetic counseling and prenatal diagnosis for reproductive risks.
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Affiliation(s)
- Li Shu
- Department of Medical Genetics, Maternal and Child Health Hospital of Hunan Province, Changsha, China.,National Health Commission Key Laboratory of Birth Defects Research, Prevention and Treatment, Hunan Provincial Maternal and Child Health Care Hospital, Changsha, China.,Department of School of Life Sciences, Central South University, Changsha, China
| | - Qianjun Zhang
- Institute of Reproductive and Stem Cell Engineering, School of Basic Medical Science, Central South University, Changsha, China.,Department of Medical Genetics, Reproductive and Genetic Hospital of CITIC-Xiangya, Changsha, China.,NHC Key Laboratory of Human Stem Cell and Reproductive Engineering, Central South University, Changsha, China
| | - Qi Tian
- Department of Medical Genetics, Maternal and Child Health Hospital of Hunan Province, Changsha, China.,National Health Commission Key Laboratory of Birth Defects Research, Prevention and Treatment, Hunan Provincial Maternal and Child Health Care Hospital, Changsha, China
| | - Sai Yang
- Department of Neurology, Children's Hospital of Hunan Province, Changsha, China
| | - Xingwang Peng
- Marketing Management Center, AmCare Genomics Laboratory, Guangzhou, China
| | - Xiao Mao
- Department of Medical Genetics, Maternal and Child Health Hospital of Hunan Province, Changsha, China.,National Health Commission Key Laboratory of Birth Defects Research, Prevention and Treatment, Hunan Provincial Maternal and Child Health Care Hospital, Changsha, China
| | - Liming Yang
- Department of Neurology, Children's Hospital of Hunan Province, Changsha, China
| | - Juan Du
- Institute of Reproductive and Stem Cell Engineering, School of Basic Medical Science, Central South University, Changsha, China.,Department of Medical Genetics, Reproductive and Genetic Hospital of CITIC-Xiangya, Changsha, China.,NHC Key Laboratory of Human Stem Cell and Reproductive Engineering, Central South University, Changsha, China
| | - Hua Wang
- Department of Medical Genetics, Maternal and Child Health Hospital of Hunan Province, Changsha, China.,National Health Commission Key Laboratory of Birth Defects Research, Prevention and Treatment, Hunan Provincial Maternal and Child Health Care Hospital, Changsha, China
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9
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Abstract
The voltage-gated sodium channel α-subunit genes comprise a highly conserved gene family. Mutations of three of these genes, SCN1A, SCN2A and SCN8A, are responsible for a significant burden of neurological disease. Recent progress in identification and functional characterization of patient variants is generating new insights and novel approaches to therapy for these devastating disorders. Here we review the basic elements of sodium channel function that are used to characterize patient variants. We summarize a large body of work using global and conditional mouse mutants to characterize the in vivo roles of these channels. We provide an overview of the neurological disorders associated with mutations of the human genes and examples of the effects of patient mutations on channel function. Finally, we highlight therapeutic interventions that are emerging from new insights into mechanisms of sodium channelopathies.
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10
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Benova B, Sanders MWCB, Uhrova-Meszarosova A, Belohlavkova A, Hermanovska B, Novak V, Stanek D, Vlckova M, Zamecnik J, Aronica E, Braun KPJ, Koeleman BPC, Jansen FE, Krsek P. GATOR1-related focal cortical dysplasia in epilepsy surgery patients and their families: A possible gradient in severity? Eur J Paediatr Neurol 2021; 30:88-96. [PMID: 33461085 DOI: 10.1016/j.ejpn.2020.12.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Revised: 10/16/2020] [Accepted: 12/04/2020] [Indexed: 12/23/2022]
Abstract
BACKGROUND Variants of GATOR1-genes represent a recognised cause of focal cortical dysplasia (FCD), the most common structural aetiology in paediatric drug-resistant focal epilepsy. Reports on familial cases of GATOR1-associated FCD are limited, especially with respect to epilepsy surgery outcomes. METHODS We present phenotypical manifestations of four unrelated patients with drug-resistant focal epilepsy, FCD and a first-degree relative with epilepsy. All patients underwent targeted gene panel sequencing as a part of the presurgical work up. Literature search was performed to compare our findings to previously published cases. RESULTS The children (probands) had a more severe phenotype than their parents, including drug-resistant epilepsy and developmental delay, and they failed to achieve seizure freedom post-surgically. All patients had histopathologically confirmed FCD (types IIa, IIb, Ia). In Patient 1 and her affected father, we detected a known pathogenic NPRL2 variant. In patients 2 and 3 and their affected parents, we found novel likely pathogenic germline DEPDC5 variants. In family 4, we detected a novel variant in NPRL3. We identified 15 additional cases who underwent epilepsy surgery for GATOR1-associated FCD, with a positive family history of epilepsy in the literature; in 8/13 tested, the variant was inherited from an asymptomatic parent. CONCLUSION The presented cases displayed a severity gradient in phenotype with children more severely affected than the parents. Although patients with GATOR1-associated FCD are considered good surgical candidates, post-surgical seizure outcome was poor in our familial cases, suggesting that accurate identification of the epileptogenic zone may be more challenging in this subgroup of patients.
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Affiliation(s)
- Barbora Benova
- Department of Paediatric Neurology, Motol Epilepsy Center, 2nd Faculty of Medicine, Charles University and Motol University Hospital, V Uvalu 84, 15006, Prague, Czech Republic; Neurogenetics Laboratory of the Department of Paediatric Neurology, 2nd Faculty of Medicine, Charles University and Motol University Hospital, V Uvalu 84, Prague, 15006, Czech Republic.
| | - Maurits W C B Sanders
- Department of Child Neurology, Brain Center University Medical Center Utrecht, the Netherlands.
| | - Anna Uhrova-Meszarosova
- Department of Paediatric Neurology, Motol Epilepsy Center, 2nd Faculty of Medicine, Charles University and Motol University Hospital, V Uvalu 84, 15006, Prague, Czech Republic; Neurogenetics Laboratory of the Department of Paediatric Neurology, 2nd Faculty of Medicine, Charles University and Motol University Hospital, V Uvalu 84, Prague, 15006, Czech Republic.
| | - Anezka Belohlavkova
- Department of Paediatric Neurology, Motol Epilepsy Center, 2nd Faculty of Medicine, Charles University and Motol University Hospital, V Uvalu 84, 15006, Prague, Czech Republic.
| | - Barbora Hermanovska
- Department of Paediatric Neurology, Motol Epilepsy Center, 2nd Faculty of Medicine, Charles University and Motol University Hospital, V Uvalu 84, 15006, Prague, Czech Republic.
| | - Vilem Novak
- Department of Paediatric Neurology, Ostrava Faculty Hospital, 17. Listopadu 1790, 708 00, Ostrava-Poruba, Czech Republic.
| | - David Stanek
- Neurogenetics Laboratory of the Department of Paediatric Neurology, 2nd Faculty of Medicine, Charles University and Motol University Hospital, V Uvalu 84, Prague, 15006, Czech Republic.
| | - Marketa Vlckova
- Department of Biology and Medical Genetics, 2nd Faculty of Medicine, Charles University and Motol University Hospital, V Uvalu 84, 15006, Prague, Czech Republic.
| | - Josef Zamecnik
- Department of Pathology and Molecular Medicine, 2nd Faculty of Medicine, Charles University and Motol University Hospital, V Uvalu 84, 15006, Prague, Czech Republic.
| | - Eleonora Aronica
- Amsterdam UMC, University of Amsterdam, Department of (Neuro)Pathology, Amsterdam, Meibergdreef 9, 1105, AZ Amsterdam, the Netherlands; Stichting Epilepsie Instellingen Nederland (SEIN), Achterweg 2, 2103, SW, Heemstede, the Netherlands.
| | - Kees P J Braun
- Department of Child Neurology, Brain Center University Medical Center Utrecht, the Netherlands.
| | - Bobby P C Koeleman
- Department of Genetics, University Medical Center Utrecht, Utrecht, the Netherlands.
| | - Floor E Jansen
- Department of Child Neurology, Brain Center University Medical Center Utrecht, the Netherlands.
| | - Pavel Krsek
- Department of Paediatric Neurology, Motol Epilepsy Center, 2nd Faculty of Medicine, Charles University and Motol University Hospital, V Uvalu 84, 15006, Prague, Czech Republic.
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11
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D'Adamo MC, Liantonio A, Conte E, Pessia M, Imbrici P. Ion Channels Involvement in Neurodevelopmental Disorders. Neuroscience 2020; 440:337-359. [PMID: 32473276 DOI: 10.1016/j.neuroscience.2020.05.032] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 05/16/2020] [Accepted: 05/19/2020] [Indexed: 12/14/2022]
Abstract
Inherited and sporadic mutations in genes encoding for brain ion channels, affecting membrane expression or biophysical properties, have been associated with neurodevelopmental disorders characterized by epilepsy, cognitive and behavioral deficits with significant phenotypic and genetic heterogeneity. Over the years, the screening of a growing number of patients and the functional characterization of newly identified mutations in ion channels genes allowed to recognize new phenotypes and to widen the clinical spectrum of known diseases. Furthermore, advancements in understanding disease pathogenesis at atomic level or using patient-derived iPSCs and animal models have been pivotal to orient therapeutic intervention and to put the basis for the development of novel pharmacological options for drug-resistant disorders. In this review we will discuss major improvements and critical issues concerning neurodevelopmental disorders caused by dysfunctions in brain sodium, potassium, calcium, chloride and ligand-gated ion channels.
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Affiliation(s)
- Maria Cristina D'Adamo
- Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, Malta
| | | | - Elena Conte
- Department of Pharmacy-Drug Sciences, University of Bari "Aldo Moro", Italy
| | - Mauro Pessia
- Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, Malta; Department of Physiology, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Paola Imbrici
- Department of Pharmacy-Drug Sciences, University of Bari "Aldo Moro", Italy.
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12
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Abstract
Developmental and epileptic encephalopathies (DEEs) can be primarily attributed to genetic causes. The genetic landscape of DEEs has been largely shaped by the rise of high-throughput sequencing, which led to the discovery of new DEE-associated genes and helped identify de novo pathogenic variants. We discuss briefly the contribution of de novo variants to DEE and also focus on alternative inheritance models that contribute to DEE. First, autosomal recessive inheritance in outbred populations may have a larger contribution than previously appreciated, accounting for up to 13% of DEEs. A small subset of genes that typically harbor de novo variants have been associated with recessive inheritance, and often these individuals have more severe clinical presentations. Additionally, pathogenic variants in X-linked genes have been identified in both affected males and females, possibly due to a lack of X-chromosome inactivation skewing. Collectively, exome sequencing has resulted in a molecular diagnosis for many individuals with DEE, but this still leaves many cases unsolved. Multiple factors contribute to the missing etiology, including nonexonic variants, mosaicism, epigenetics, and oligogenic inheritance. Here, we focus on the first 2 factors. We discuss the promises and challenges of genome sequencing, which allows for a more comprehensive analysis of the genome, including interpretation of structural and noncoding variants and also yields a high number of de novo variants for interpretation. We also consider the contribution of genetic mosaicism, both what it means for a molecular diagnosis in mosaic individuals and the important implications for genetic counseling.
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Affiliation(s)
- Hannah C Happ
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Gemma L Carvill
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
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13
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Highly Sensitive Blocker Displacement Amplification and Droplet Digital PCR Reveal Low-Level Parental FOXF1 Somatic Mosaicism in Families with Alveolar Capillary Dysplasia with Misalignment of Pulmonary Veins. J Mol Diagn 2020; 22:447-456. [PMID: 32036090 DOI: 10.1016/j.jmoldx.2019.12.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Revised: 10/30/2019] [Accepted: 12/11/2019] [Indexed: 12/20/2022] Open
Abstract
Detection of low-level somatic mosaicism [alternate allele fraction (AAF) ≤ 10%] in parents of affected individuals with the apparent de novo pathogenic variants enables more accurate estimate of recurrence risk. To date, only a few systematic analyses of low-level parental somatic mosaicism have been performed. Herein, highly sensitive blocker displacement amplification, droplet digital PCR, quantitative PCR, long-range PCR, and array comparative genomic hybridization were applied in families with alveolar capillary dysplasia with misalignment of pulmonary veins. We screened 18 unrelated families with the FOXF1 variant previously determined to be apparent de novo (n = 14), of unknown parental origin (n = 1), or inherited from a parent suspected to be somatic and/or germline mosaic (n = 3). We identified four (22%) families with FOXF1 parental somatic mosaic single-nucleotide variants (n = 3) and copy number variant deletion (n = 1) detected in parental blood samples and an AAF ranging between 0.03% and 19%. In one family, mosaic allele ratio in tissues originating from three germ layers ranged between <0.03% and 0.65%. Because the ratio of parental somatic mosaicism have significant implications for the recurrence risk, this study further implies the importance of a systematic screening of parental samples for low-level and very-low-level (AAF ≤ 1%) somatic mosaicism using methods that are more sensitive than those routinely applied in diagnostics.
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14
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Vidal S, Xiol C, Pascual-Alonso A, O'Callaghan M, Pineda M, Armstrong J. Genetic Landscape of Rett Syndrome Spectrum: Improvements and Challenges. Int J Mol Sci 2019; 20:ijms20163925. [PMID: 31409060 PMCID: PMC6719047 DOI: 10.3390/ijms20163925] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 08/08/2019] [Accepted: 08/10/2019] [Indexed: 02/06/2023] Open
Abstract
Rett syndrome (RTT) is an early-onset neurodevelopmental disorder that primarily affects females, resulting in severe cognitive and physical disabilities, and is one of the most prevalent causes of intellectual disability in females. More than fifty years after the first publication on Rett syndrome, and almost two decades since the first report linking RTT to the MECP2 gene, the research community's effort is focused on obtaining a better understanding of the genetics and the complex biology of RTT and Rett-like phenotypes without MECP2 mutations. Herein, we review the current molecular genetic studies, which investigate the genetic causes of RTT or Rett-like phenotypes which overlap with other genetic disorders and document the swift evolution of the techniques and methodologies employed. This review also underlines the clinical and genetic heterogeneity of the Rett syndrome spectrum and provides an overview of the RTT-related genes described to date, many of which are involved in epigenetic gene regulation, neurotransmitter action or RNA transcription/translation. Finally, it discusses the importance of including both phenotypic and genetic diagnosis to provide proper genetic counselling from a patient's perspective and the appropriate treatment.
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Affiliation(s)
- Silvia Vidal
- Sant Joan de Déu Research Foundation, 08950 Barcelona, Spain
- Institut de Recerca Pediàtrica Hospital Sant Joan de Déu, 08950 Barcelona, Spain
| | - Clara Xiol
- Sant Joan de Déu Research Foundation, 08950 Barcelona, Spain
- Institut de Recerca Pediàtrica Hospital Sant Joan de Déu, 08950 Barcelona, Spain
| | - Ainhoa Pascual-Alonso
- Sant Joan de Déu Research Foundation, 08950 Barcelona, Spain
- Institut de Recerca Pediàtrica Hospital Sant Joan de Déu, 08950 Barcelona, Spain
| | - M O'Callaghan
- Institut de Recerca Pediàtrica Hospital Sant Joan de Déu, 08950 Barcelona, Spain
- Neurology Service, Hospital Sant Joan de Déu, 08950 Barcelona, Spain
- CIBER-ER (Biomedical Network Research Center for Rare Diseases), Institute of Health Carlos III (ISCIII), 28029 Madrid, Spain
| | - Mercè Pineda
- Sant Joan de Déu Research Foundation, 08950 Barcelona, Spain
| | - Judith Armstrong
- Institut de Recerca Pediàtrica Hospital Sant Joan de Déu, 08950 Barcelona, Spain.
- CIBER-ER (Biomedical Network Research Center for Rare Diseases), Institute of Health Carlos III (ISCIII), 28029 Madrid, Spain.
- Molecular and Genetics Medicine Section, Hospital Sant Joan de Déu, 08950 Barcelona, Spain.
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15
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Møller RS, Liebmann N, Larsen LHG, Stiller M, Hentschel J, Kako N, Abdin D, Di Donato N, Pal DK, Zacher P, Syrbe S, Dahl HA, Lemke JR. Parental mosaicism in epilepsies due to alleged de novo variants. Epilepsia 2019; 60:e63-e66. [PMID: 31077350 DOI: 10.1111/epi.15187] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 04/02/2019] [Accepted: 04/15/2019] [Indexed: 02/03/2023]
Abstract
Severe early onset epilepsies are often caused by de novo pathogenic variants. Few studies have reported the frequency of somatic mosaicism in parents of children with severe epileptic encephalopathies. Here we aim to investigate the frequency of mosaicism in the parents of children with epilepsy caused by alleged de novo variants. We tested parental genomic DNA derived from different tissues for 75 cases using targeted next-generation sequencing. Five parents (6.6%) showed mosaicism at minor allele frequencies of 0.8%-29% for the pathogenic variant detected in their offspring. Parental mosaicism was observed in the following genes: SCN1A, SCN2A, SCN8A, and STXBP1. One of the identified parents had epilepsy himself. Our results show that de novo events can occur already in parental tissue and in some cases can be detected in peripheral blood. Consequently, parents affected by low-grade mosaicism are faced with an increased recurrence risk for transmitting the pathogenic variant, compared to the overall recurrence risk for a second affected child estimated at approximately 1%. However, testing for parental somatic mosaicism will help identifying those parents who truly are at higher risk and will significantly improve genetic counseling in the respective families.
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Affiliation(s)
- Rikke S Møller
- Danish Epilepsy Centre, Dianalund, Denmark
- Institute of Regional Health Research, University of Southern Denmark, Odense, Denmark
| | - Nora Liebmann
- Institute of Human Genetics, University of Leipzig Medical Center, Leipzig, Germany
| | | | - Mathias Stiller
- Institute of Human Genetics, University of Leipzig Medical Center, Leipzig, Germany
| | - Julia Hentschel
- Institute of Human Genetics, University of Leipzig Medical Center, Leipzig, Germany
| | | | - Dalia Abdin
- Institute for Clinical Genetics, TU Dresden, Dresden, Germany
| | | | - Deb K Pal
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
- MRC Centre for Neurodevelopmental Disorders, King's College London, London, UK
- King's College Hospital, London, UK
- Evelina London Children's Hospital, London, UK
| | - Pia Zacher
- The Saxon Epilepsy Center Kleinwachau, Radeberg, Germany
| | - Steffen Syrbe
- Department of General Paediatrics, Division of Child Neurology and Inherited Metabolic Diseases, Centre for Paediatrics and Adolescent Medicine, University Hospital Heidelberg, Heidelberg, Germany
| | | | - Johannes R Lemke
- Institute of Human Genetics, University of Leipzig Medical Center, Leipzig, Germany
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