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Wong‐Spracklen VMY, Kolesnik A, Eck J, Sabanathan S, Spasic‐Boskovic O, Maw A, Baker K. Biallelic CACNA1A variants: Review of literature and report of a child with drug-resistant epilepsy and developmental delay. Am J Med Genet A 2022; 188:3306-3311. [PMID: 36063114 PMCID: PMC9826308 DOI: 10.1002/ajmg.a.62960] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 07/19/2022] [Accepted: 07/24/2022] [Indexed: 01/31/2023]
Abstract
Biallelic variants in CACNA1A have previously been reported in nine individuals (four families) presenting with epilepsy and cognitive impairments of variable severity and age-of-onset. Here, we describe a child who presented at 6 months of age with drug-resistant epilepsy and developmental delay. At 10 years of age, she has profound impairments in motor function and communication. MRI was initially unremarkable, but progressed to severe cerebellar atrophy by age 3 years. Next Generation Sequencing and panel analysis identified a maternally inherited truncating variant c.2042_2043delAG, p.(Gln681ArgfsTer100) and paternally inherited missense variant c.1693G>A, p.(Glu565Lys). In contrast to previously reported biallelic cases, parents carrying these monoallelic variants did not display clear signs of a CACNA1A-associated syndrome. In conclusion, we provide further evidence that biallelic CACNA1A variants can cause a severe epileptic and developmental encephalopathy with progressive cerebellar atrophy, and highlight complexities of genetic counseling in such situations.
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Affiliation(s)
| | - Anna Kolesnik
- MRC Cognition and Brain Sciences UnitUniversity of CambridgeCambridgeUK
| | - Josefine Eck
- MRC Cognition and Brain Sciences UnitUniversity of CambridgeCambridgeUK
| | - Saras Sabanathan
- Department of Paediatric NeurosciencesEvelina Childrens HospitalLondonUK
| | | | - Anna Maw
- Department of Paediatric NeurologyCambridge University Hospitals NHS Foundation TrustCambridgeUK
| | - Kate Baker
- MRC Cognition and Brain Sciences UnitUniversity of CambridgeCambridgeUK
- Department of Medical GeneticsUniversity of CambridgeCambridgeUK
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Xu Y, Wang Z, Sun Q, Zhou L, Xu H, Hu Y. Clinical features and CACNA1A gene mutation in a family with episodic ataxia type 2. ZHONG NAN DA XUE XUE BAO. YI XUE BAN = JOURNAL OF CENTRAL SOUTH UNIVERSITY. MEDICAL SCIENCES 2022; 47:801-808. [PMID: 35837781 PMCID: PMC10930023 DOI: 10.11817/j.issn.1672-7347.2022.210650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Indexed: 06/15/2023]
Abstract
Episodic ataxia (EA) is a group of disorders characterized by recurrent spells of vertigo, truncal ataxia, and dysarthria. Episodic ataxia type 2 (EA2), the most common subtype of EA, is an autosomal dominant disease caused by mutation of the CACNA1A gene. EA2 has been rarely reported in the Chinese population. Here we present an EA2 family admitted to Xiangya Hospital in October 2018. The proband was a 22-year-old male who complained of recurrent spells of vertigo, slurred speech, and incoordination for 4 years. Brain magnetic resonance imaging (MRI) showed cerebellar atrophy. He had neuropsychological development disorder in childhood, and cognitive assessment in adulthood showed cognitive impairment. The proband's mother and grandmother had a similar history. Peripheral blood samples from the proband and family members were collected, and genomic DNA was isolated. Whole exome sequencing of the proband detected a heterozygous frameshift mutation c.2042_2043del (p.Q681Rfs*100) of CACNA1A gene. This mutation was verified in the proband and 2 family members using Sanger sequencing. One family member carrying this mutation was free of symptoms and signs, suggesting an incomplete penetrance of the mutation. We reported a variant c.2042_2043del of CACNA1A gene as the pathogenic mutation in a Chinese EA2 family for the first time. This case enriched the clinical spectrum of CACNA1A related EA2, and contributed to the understanding of clinical and genetic characteristics of EA2 to reduce misdiagnosis.
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Affiliation(s)
- Yinghui Xu
- Department of Geriatric Neurology, Xiangya Hospital, Central South University, Changsha 410008.
| | - Zhiqin Wang
- Department of Geriatric Neurology, Xiangya Hospital, Central South University, Changsha 410008
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Changsha 410008, China
| | - Qiying Sun
- Department of Geriatric Neurology, Xiangya Hospital, Central South University, Changsha 410008
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Changsha 410008, China
| | - Lin Zhou
- Department of Geriatric Neurology, Xiangya Hospital, Central South University, Changsha 410008
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Changsha 410008, China
| | - Hongwei Xu
- Department of Geriatric Neurology, Xiangya Hospital, Central South University, Changsha 410008
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Changsha 410008, China
| | - Yacen Hu
- Department of Geriatric Neurology, Xiangya Hospital, Central South University, Changsha 410008.
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Changsha 410008, China.
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Abstract
Episodic ataxia (EA) is a rare neurological condition characterized by recurrent spells of truncal ataxia and incoordination. Five genes (KCNA1, CACNA1A, CACNB4, SLC1A3, and UBR4) have been linked to EA. Despite extensive efforts to genetically diagnose EA, many patients remain still undiagnosed. Whole-exome sequencing was carried out in 39 Korean patients with EA to identify pathogenic mutations of the five known EA genes. We also evaluated 40 candidate genes that cause EA as a secondary phenotype or cerebellar ataxia. Eighteen patients (46%) revealed genetic information useful for establishing a molecular diagnosis of EA. In 11 patients, 16 pathogenic mutations were detected in three EA genes. These included nine mutations in CACNA1A, three in SLC1A3, and four in UBR4. Three patients had mutations in two genes, either CACNA1A and SLC1A3 or CACNA1A and UBR4, suggesting that SLC1A3 and UBR4 may act as genetic modifiers with synergic effects on the abnormal presynaptic activity caused by CACNA1A mutations. In seven patients with negative results for screening of EA genes, potential pathogenic mutations were identified in the candidate genes ATP1A2, SCN1A, TTBK2, TGM6, FGF14, and KCND3. This study demonstrates the genetic heterogeneity of Korean EA, and indicates that whole-exome sequencing may be useful for molecular genetic diagnosis of EA.
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Mutation Spectrum in the CACNA1A Gene in 49 Patients with Episodic Ataxia. Sci Rep 2017; 7:2514. [PMID: 28566750 PMCID: PMC5451382 DOI: 10.1038/s41598-017-02554-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 04/13/2017] [Indexed: 11/08/2022] Open
Abstract
Episodic ataxia is an autosomal dominant ion channel disorder characterized by episodes of imbalance and incoordination. The disease is genetically heterogeneous and is classified as episodic ataxia type 2 (EA2) when it is caused by a mutation in the CACNA1A gene, encoding the α1A subunit of the P/Q-type voltage-gated calcium channel Cav2.1. The vast majority of EA2 disease-causing variants are loss-of-function (LoF) point changes leading to decreased channel currents. CACNA1A exonic deletions have also been reported in EA2 using quantitative approaches. We performed a mutational screening of the CACNA1A gene, including the promoter and 3'UTR regions, in 49 unrelated patients diagnosed with episodic ataxia. When pathogenic variants were not found by sequencing, we performed a copy number variant (CNV) analysis to screen for duplications or deletions. Overall, sequencing screening allowed identification of six different point variants (three nonsense and three missense changes) and two coding indels, one of them found in two unrelated patients. Additionally, CNV analysis identified a deletion in a patient spanning exon 35 as a result of a recombination event between flanking intronic Alu sequences. This study allowed identification of potentially pathogenic alterations in our sample, five of them novel, which cover 20% of the patients (10/49). Our data suggest that most of these variants are disease-causing, although functional studies are required.
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Choi KD, Choi JH. Episodic Ataxias: Clinical and Genetic Features. J Mov Disord 2016; 9:129-35. [PMID: 27667184 PMCID: PMC5035943 DOI: 10.14802/jmd.16028] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 07/25/2016] [Accepted: 08/01/2016] [Indexed: 11/24/2022] Open
Abstract
Episodic ataxia (EA) is a clinically heterogeneous group of disorders that are characterized by recurrent spells of truncal ataxia and incoordination lasting minutes to hours. Most have an autosomal dominant inheritance pattern. To date, 8 subtypes have been defined according to clinical and genetic characteristics, and five genes are known to be linked to EAs. Both EA1 and EA2, which are caused by mutations in KCNA1 and CACNA1A, account for the majority of EA, but many patients with no identified mutations still exhibit EA-like clinical features. Furthermore, genetically confirmed EAs have mostly been identified in Caucasian families. In this article, we review the current knowledge on the clinical and genetic characteristics of EAs. Additionally, we summarize the phenotypic features of the genetically confirmed EA2 families in Korea.
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Affiliation(s)
- Kwang-Dong Choi
- Department of Neurology, College of Medicine, Pusan National University Hospital, Pusan National University School of Medicine and Biomedical Research Institute, Busan, Korea
| | - Jae-Hwan Choi
- Department of Neurology, Pusan National University School of Medicine, Research Institute for Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital, Yangsan, Korea
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Exercise-induced downbeat nystagmus in a Korean family with a nonsense mutation in CACNA1A. Neurol Sci 2015; 36:1393-6. [PMID: 25784583 DOI: 10.1007/s10072-015-2157-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Accepted: 03/06/2015] [Indexed: 10/23/2022]
Abstract
Episodic ataxia type 2 (EA2) is characterized by recurrent attacks of vertigo and ataxia lasting hours triggered by emotional stress or exercise. Although interictal horizontal gaze-evoked nystagmus and rebound nystagmus are commonly observed in patients with EA2, the nystagmus has been rarely reported during the vertigo attack. To better describe exercise-induced nystagmus in EA2, four affected members from three generations of a Korean family with EA2 received full neurological and neuro-otological evaluations. Vertigo was provoked in the proband with running for 10 min to record eye movements during the vertigo attack. We performed a polymerase chain reaction-based direct sequence analysis of all coding regions of CACNA1A in all participants. The four affected members had a history of exertional vertigo, imbalance, childhood epilepsy, headache, and paresthesia. The provocation induced severe vertigo and imbalance lasting several hours, and oculography documented pure downbeat nystagmus during the attack. Genetic analyses identified a nonsense mutation in exon 23 which has been registered in dbSNP as a pathogenic allele (c.3832C>T, p.R1278X) in all the affected members. Ictal downbeat nystagmus in the studied family indicates cerebellar dysfunction during the vertigo attack in EA2. In patients with episodic vertigo and ataxia, the observation of exercise-induced nystagmus would provide a clue for EA2.
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Episodic ataxia type 2: phenotype characteristics of a novel CACNA1A mutation and review of the literature. J Neurol 2014; 261:983-91. [DOI: 10.1007/s00415-014-7310-2] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Revised: 03/05/2014] [Accepted: 03/05/2014] [Indexed: 10/25/2022]
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Choi KD, Yook JW, Kim MJ, Kim HS, Park YE, Kim JS, Choi JH, Shin JH, Kim DS. Possible anticipation associated with a novel splice site mutation in episodic ataxia type 2. Neurol Sci 2013; 34:1629-32. [PMID: 23344743 DOI: 10.1007/s10072-013-1298-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2012] [Accepted: 01/07/2013] [Indexed: 10/27/2022]
Abstract
Anticipation is a phenomenon characterized by decreasing age at onset and increasing severity of symptoms of a disease in successive generations within a pedigree. Anticipation mostly occurs in neurodegenerative diseases with expansion of unstable trinucleotide repeats. However, it has not been previously pointed out in episodic ataxia type 2 (EA2). Clinical and genetic analyses were performed in nine members from three consecutive generations of a Korean family with EA2. We performed a polymerase chain reaction (PCR)-based direct sequence analysis of all coding regions of CACNA1A using genomic DNA. The clinically affected family members showed recurrent vertigo, interictal nystagmus, and childhood epilepsy. There is a decrease in the age onset (possible genetic anticipation) in three succeeding generations of the family. Genetic analysis identified a splice site mutation (p.Val1465Glyfs13X) and normal trinucleotide repeats in CACNA1A in all clinically affected and one unaffected members. Recognizing anticipation would aid in genetic counseling in EA2.
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Affiliation(s)
- Kwang-Dong Choi
- Department of Neurology, Pusan National University Hospital, Pusan National University School of Medicine and Biomedical Research Institute, Pusan, Korea
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SHERVIN BADV R, NIKSIRAT A. Downward vertical gaze palsy as a prominent manifestation of episodic ataxia type 2: a case report. IRANIAN JOURNAL OF CHILD NEUROLOGY 2013; 7:58-60. [PMID: 24665320 PMCID: PMC3943042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Revised: 04/30/2013] [Accepted: 05/12/2013] [Indexed: 10/25/2022]
Abstract
OBJECTIVE Episodic ataxia type 2 (EA2) is an inherited autosomal dominant disorder characterized by intermittent ataxia, nausea, vomiting, dysarthria, or nystagmus. We report a case of EA2, which downward gaze palsy exists as a common sign in all her attacks. Responsiveness of EA2 to acetazolamide was observed in this patient.
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Affiliation(s)
- Reza SHERVIN BADV
- Pediatric Neurologist, Department of Pediatrics, Zanjan University of Medical Sciences, Zanjan, Iran
| | - Ali NIKSIRAT
- Legal Medicine Research Center, Legal Medicine Organization, Tehran, Iran
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Choi KH, Kim JS, Lee SY, Ryu SW, Kim SS, Lee SH, Kim S, Park HK. Familial hemiplegic migraine with prolonged coma and cerebellar atrophy: CACNA1A T666M mutation in a Korean family. J Korean Med Sci 2012; 27:1124-7. [PMID: 22969264 PMCID: PMC3429835 DOI: 10.3346/jkms.2012.27.9.1124] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Accepted: 05/25/2012] [Indexed: 11/20/2022] Open
Abstract
We report the first Korean patient with familial hemiplegic migraine type 1, with clinical and multimodal imaging findings. A 43-yr-old man was admitted for right hemianopia and aphasia, followed by coma. MRI showed only cerebellar atrophy. CT angiography showed mild vasodilation of intracranial blood vessels and increased vascularity in the left hemisphere and perfusion-weighted imaging showed elevated cerebral blood flow. Gene analysis of the patient and his mother led to the identification of a heterozygous point mutation (1997C→T, T666M) in exon 16 of the CACNA1A gene. Familial hemiplegic migraine should be considered in patients with episodic neurological dysfunction with cerebellar atrophy.
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Affiliation(s)
- Kyung-Ho Choi
- Department of Neurology, College of Medicine, Kangwon National University Hospital, Chuncheon, Korea
| | - Jang Su Kim
- Department of Laboratory Medicine & Genetics, Korea University College of Medicine, Korea University Guro Hospital, Seoul, Korea
| | - Seo-Young Lee
- Department of Neurology, College of Medicine, Kangwon National University Hospital, Chuncheon, Korea
| | - Suk-won Ryu
- Department of Laboratory Medicine, College of Medicine, Kangwon National University Hospital, Chuncheon, Korea
| | - Sam Su Kim
- Department of Radiology, College of Medicine, Kangwon National University Hospital, Chuncheon, Korea
| | - Seung-hwan Lee
- Department of Neurology, College of Medicine, Kangwon National University Hospital, Chuncheon, Korea
| | - Sunghun Kim
- Department of Neurology, College of Medicine, Kangwon National University Hospital, Chuncheon, Korea
| | - Hee-Kwon Park
- Department of Neurology, College of Medicine, Inha University Hospital, Incheon, Korea
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