Novel Myoclonin1/EFHC1 Mutations in Mexican Patients with Juvenile

View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Elsevier - Publisher Connector Seizure 21 (2012) 550–554 Contents lists available at SciVerse ScienceDirect Seizure jou rnal homepage: www.elsevier.com/locate/yseiz Short communication Novel Myoclonin1/EFHC1 mutations in Mexican patients with juvenile myoclonic epilepsy a b a a Aurelio Jara-Prado , Iris E. Martıńez-Jua´rez , Adriana Ochoa , Vıćtor M. Gonza´lez , c d e Marıá del Carmen Fernańdez-Gonza´lez-Arago´ n , Minerva Lo´ pez-Ruiz , Marco T. Medina , f f a, Julia N. Bailey , Antonio V. Delgado-Escueta , Marıá Elisa Alonso * a Neurogenetics and Molecular Biology Department, National Institute of Neurology and Neurosurgery of Mexico, Insurgentes Sur 3877, Col. La Fama, Tlalpan, Me´xico D.F. 14269, Mexico b Epilepsy Clinic, National Institute of Neurology and Neurosurgery of Mexico, Insurgentes Sur 3877, Col. La Fama, Tlalpan, Me´xico D.F. 14269, Mexico c Clinical Neurophysiology Department, National Institute of Neurology and Neurosurgery of Mexico, Insurgentes Sur 3877, Col. La Fama, Tlalpan, Me´xico D.F. 14269, Mexico d Neurology and Neurosurgery Unit, Mexico General Hospital, Dr. Balmis 161, Col. Doctores, Mexico D.F, Mexico e National Autonomous University of Honduras, Tegucigalpa, Honduras f Epilepsy Genetics/Genomics Laboratories and Epilepsy Center of Excellence, Neurology and Research Services, VA GLAHS and David Geffen School of Medicine at UCLA, Los Angeles, CA 90073, USA A R T I C L E I N F O A B S T R A C T Article history: Purpose: The purpose of this study was to identify the prevalence of mutations in the Myoclonin1/EFHC1 Received 1 February 2012 gene in Mexican patients with juvenile myoclonic epilepsy (JME). Received in revised form 28 May 2012 Method: We studied forty-one patients at the National Institute of Neurology and Neurosurgery in Accepted 29 May 2012 Mexico City and 100 healthy controls. DNA was extracted from the peripheral venous blood of all participants. The exons of EFHC1 were then amplified and sequenced. Keywords: Results: We found three new putative mutations, all of which were heterozygous missense mutations Juvenile myoclonic epilepsy located in exon 3. The first identified mutation, 352C>T, produces a R118C change in the protein and EFHC1 gene cosegregated in the patient’s affected father and brother. The second identified mutation, 544C>T, Mutations produces a R182L change in the protein and was found in the patient’s asymptomatic father. The third identified mutation, 458>A, produces a R153Q change in the protein and was also found in the patient’s father. These mutations were not found in controls. Conclusions: The frequency of Myoclonin1/EFHC1 mutations in our sample is 7.3%. Thus, we conclude that mutations in the Myoclonin1/EFHC1 gene are an important cause of JME in Mexican patients. ß 2012 British Epilepsy Association. Published by Elsevier Ltd. All rights reserved. 1. Introduction Honduras and Mexico and 3% of JME patients from Japan were found to carry heterozygous missense, nonsense and deletion frameshift 5 Juvenile myoclonic epilepsy (JME) is one of the most common mutations in the EFHC1 gene. Here, we report the presence of three 1 types of genetic generalized epilepsy. JME is characterized by additional novel EFHC1 heterozygous missense mutations in a new adolescent onset, infrequent absence seizures, awakening myoclon- cohort of forty-one Mexican JME patients. We also compared the ic seizures and generalized tonic–clonic (GTC) or clonic–tonic– presence of the JME subsyndromes and the persistence of seizures in clonic (CTC) seizures. Two JME-causing genes have been identified JME patients with and without EFHC1 mutations. and their associations with JME have been replicated. These genes 2,3 include GABRA1 on chromosome 5q34q35 and EFHC1 on 2. Methods 4 chromosome 6p12. In another study, 9% of JME patients from 2.1. Patient and family samples * Corresponding author at: Insurgentes Sur #3877, Col. La Fama, Del. Tlalpan, Forty-one Mexican JME patients were recruited for the present Mexico City 14269, Mexico. Tel.: +52 55 56063822x2022; fax: +52 55 54240808. study from the National Institute of Neurology and Neurosurgery E-mail addresses: [email protected] (A. Jara-Prado), (NINN) in Mexico City. The diagnosis of JME was established by two [email protected] (I.E. Martıńez-Jua´rez), [email protected] epileptologists using the following inclusion criteria. (a) The onset (M.d.C. Fernańdez-Gonza´lez-Arago´ n), [email protected] (M. Lo´ pez-Ruiz), [email protected] (M.T. Medina), [email protected] of myoclonic seizures presented between 8 and 20 years of age. The (A.V. Delgado-Escueta), [email protected] (M.E. Alonso). myoclonic seizures experienced by the patient were characterized 1059-1311/$ – see front matter ß 2012 British Epilepsy Association. Published by Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.seizure.2012.05.016 A. Jara-Prado et al. / Seizure 21 (2012) 550–554 551 by short, bilateral, symmetrical or asymmetrical muscular contrac- JME phenotypes and the persistence of seizures between patients 2 tions. These seizures predominantly manifested in the shoulders with and without EFHC1 mutations were made using x or Fisher’s and arms and were less frequently observed in the legs. There was no exact test. The data were analyzed using SPSS version 17. evidence of loss of consciousness with the seizures. (b) Interictal EEG of the patient showed diffuse, bilateral, symmetrical and synchro- 2.2. DNA sequencing nous 3–6 Hz spike, polyspike and slow wave complexes. (c) The presence of GTC or CTC seizures at the onset or over the course of the Peripheral venous blood was drawn from forty-one JME patients disease. (d) The patient was required to have a normal neurological and 100 healthy controls. Blood was also drawn from seven family exam. (e) The patient was required to have normal brain members of the probands with EFHC1 mutations. DNA was extracted neuroimaging studies, such as computed tomography and/or from each blood sample using the QIAmp DNA blood Mini Kit magnetic resonance imaging, at the onset of symptoms. (QIAGEN, Valencia, CA, USA). The exons of EFHC1 were amplified The exclusion criteria for patients in the study included: (a) using the primers and polymerase chain reaction (PCR) conditions 4 history of symptomatic seizures; (b) family history of progressive described by Suzuki et al. The PCR products were then purified and myoclonic epilepsy; (c) evidence of a progressive neurological sequenced using the Big Dye Terminator sequencing reactions in an disease that could cause epilepsy and (d) presence of simple partial automated DNA sequencer (ABI PRISM 3130 Applied Biosystems, 5 or complex seizures. When EFHC1 mutations were identified in Foster City, CA). The identified variants were sequenced at least the patients, blood was drawn from the proband’s family members twice in both the forward and reverse directions. for DNA analysis. The family members also underwent EEG. Informed consent was obtained from all participants, and the study 3. Results was approved by the Bioethics Committee of the NINN. We also obtained the donated blood samples of 100 anonymous individuals 3.1. Clinical characteristics without a history of seizures from the NINN blood bank. These samples were tested as ethnically matched healthy controls. Next, In our cohort of 41 JME patients, 25 (61%) were female. The average we categorized each of the forty-one JME patients into one of the age at onset of epilepsy was 14.24 years (range 5–20 years). Twenty- 1 four previously described JME subsyndromes. Comparisons of the one subjects (51.2%) had a positive family history of epilepsy. The Fig. 1. Families with novel EFHC1 mutations. Brief description: Circles: female; Square: male; Circles and square filled: affected subjects; Circles and square empty: non affected subjects; M: mutated; N: no mutated. *Normal EEG. **Abnormal EEG. 552 A. Jara-Prado et al. / Seizure 21 (2012) 550–554 Fig. 2. majority (33 or 80%) of the patients met the criteria for classic JME, also found in the patient’s affected father and brother (Fig. 1A). The four patients (10%) had CAE that evolved into JME, two patients (5%) second mutation, 544C>T, substitutes lysine for arginine at met the criteria for JME with adolescent-onset pyknoleptic and two position 182 of the protein (R182L). The patient’s asymptomatic patients (5%) met the criteria for JME with astatic seizures. father, who had a normal EEG, also carried the same mutation (Fig. 1B). The third mutation, 458G>A, replaces an arginine with 3.2. Mutation analysis glutamine at position 153 of the protein (R153Q). The patient’s asymptomatic father also carried this mutation (Fig. 1C). None of The three new mutations (7.3%) identified in this cohort of JME these mutations were found in the controls. patients were heterozygous missense mutations. They have not The three identified missense mutations, R118C, R153Q and been previously reported in the single nucleotide polymorphism R182C, are found in exon 3. In silico analysis shows that the affected database (SNPs). All three of the novel mutations are located in region includes part of the first DM10 domain (position 93–198) exon 3 of the EFHC1 gene. The first identified mutation, 352C>T, (Figs. 2 and 3) and resides in an evolutionary conserved amino acid changes the Myoclonin1 protein by substituting cysteine for sequence (EMBL Clustal W2). These mutations were predicted to arginine at amino acid position 118 (R118C). This mutation was have damaging effects on function by the Polyphen program. The Protein 1 300 640 DM1 DM1 DM1 EF 93-198 239-359 416-520 579-639 Gene rs804506 rs3804505 rs1266787 rs17851770 1 2 3 4 5 6 7 8 9 10 11 P77T I174 D210N F229L T252K D253Y C259Y A394S N606N R221 R118C R153Q R182L New mutationsare shown in bold type Fig.

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