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van der Veen S, Eggink H, Elting JWJ, Sival D, Verschuuren-Bemelmans CC, de Koning TJ, Tijssen MAJ. The natural history of progressive myoclonus ataxia. Neurobiol Dis 2024; 199:106555. [PMID: 38844245 DOI: 10.1016/j.nbd.2024.106555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2024] [Revised: 05/22/2024] [Accepted: 06/03/2024] [Indexed: 06/16/2024] Open
Abstract
Progressive myoclonus ataxia (PMA) is a rare clinical syndrome characterized by the presence of progressive myoclonus and ataxia, and can be accompanied by mild cognitive impairment and infrequent epileptic seizures. This is the first study to describe the natural history of PMA and identify clinical, electrophysiological, and genetic features explaining the variability in disease progression. A Dutch cohort of consecutive patients meeting the criteria of the refined definition of PMA was included. The current phenotype was assessed during in-person consultation by movement disorders experts, and retrospective data was collected to describe disease presentation and progression, including brain imaging and therapy efficacy. Extensive genetic and electrophysiological tests were performed. The presence of cortical hyperexcitability was determined, by either the identification of a cortical correlate of myoclonic jerks with simultaneous electromyography-electroencephalography or a giant somatosensory evoked potential. We included 34 patients with PMA with a median disease duration of 15 years and a clear progressive course in most patients (76%). A molecular etiology was identified in 82% patients: ATM, CAMTA1, DHDDS, EBF3, GOSR2, ITPR1, KCNC3, NUS1, POLR1A, PRKCG, SEMA6B, SPTBN2, TPP1, ZMYND11, and a 12p13.32 deletion. The natural history is a rather homogenous onset of ataxia in the first two years of life followed by myoclonus in the first 5 years of life. Main accompanying neurological dysfunctions included cognitive impairment (62%), epilepsy (38%), autism spectrum disorder (27%), and behavioral problems (18%). Disease progression showed large variability ranging from an epilepsy free PMA phenotype (62%) to evolution towards a progressive myoclonus epilepsy (PME) phenotype (18%): the existence of a PMA-PME spectrum. Cortical hyperexcitability could be tested in 17 patients, and was present in 11 patients and supported cortical myoclonus. Interestingly, post-hoc analysis showed that an absence of cortical hyperexcitability, suggesting non-cortical myoclonus, was associated with the PMA-end of the spectrum with no epilepsy and milder myoclonus, independent of disease duration. An association between the underlying genetic defects and progression on the PMA-PME spectrum was observed. By describing the natural history of the largest cohort of published patients with PMA so far, we see a homogeneous onset with variable disease progression, in which phenotypic evolution to PME occurs in the minority. Genetic and electrophysiological features may be of prognostic value, especially the determination of cortical hyperexcitability. Furthermore, the identification of cortical and non-cortical myoclonus in PMA helps us gain insight in the underlying pathophysiology of myoclonus.
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Affiliation(s)
- Sterre van der Veen
- Department of Neurology, University of Groningen, University Medical Centre Groningen, 9700 RB, Groningen, the Netherlands; Expertise Centre Movement Disorders Groningen, University Medical Centre Groningen, 9700 RB, Groningen, the Netherlands
| | - Hendriekje Eggink
- Department of Neurology, University of Groningen, University Medical Centre Groningen, 9700 RB, Groningen, the Netherlands; Expertise Centre Movement Disorders Groningen, University Medical Centre Groningen, 9700 RB, Groningen, the Netherlands
| | - Jan Willem J Elting
- Department of Neurology, University of Groningen, University Medical Centre Groningen, 9700 RB, Groningen, the Netherlands; Expertise Centre Movement Disorders Groningen, University Medical Centre Groningen, 9700 RB, Groningen, the Netherlands
| | - Deborah Sival
- Expertise Centre Movement Disorders Groningen, University Medical Centre Groningen, 9700 RB, Groningen, the Netherlands; Department of Pediatrics, University of Groningen, University Medical Center Groningen, 9700 RB, Groningen, the Netherlands
| | - Corien C Verschuuren-Bemelmans
- Expertise Centre Movement Disorders Groningen, University Medical Centre Groningen, 9700 RB, Groningen, the Netherlands; Department of Genetics, University of Groningen, University Medical Centre Groningen, 9700 RB, Groningen, the Netherlands
| | - Tom J de Koning
- Expertise Centre Movement Disorders Groningen, University Medical Centre Groningen, 9700 RB, Groningen, the Netherlands; Department of Genetics, University of Groningen, University Medical Centre Groningen, 9700 RB, Groningen, the Netherlands; Pediatrics, department of Clinical Sciences, Lund University, 22185 Lund, Sweden
| | - Marina A J Tijssen
- Department of Neurology, University of Groningen, University Medical Centre Groningen, 9700 RB, Groningen, the Netherlands; Expertise Centre Movement Disorders Groningen, University Medical Centre Groningen, 9700 RB, Groningen, the Netherlands.
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Williams LJ, Waller S, Qiu J, Innes E, Elserafy N, Procopis P, Sampaio H, Mahant N, Tchan MC, Mohammad SS, Morales‐Briceño H, Fung VS. DHDDS and NUS1: A Converging Pathway and Common Phenotype. Mov Disord Clin Pract 2024; 11:76-85. [PMID: 38291835 PMCID: PMC10828623 DOI: 10.1002/mdc3.13920] [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: 03/06/2023] [Revised: 08/11/2023] [Accepted: 10/23/2023] [Indexed: 02/01/2024] Open
Abstract
BACKGROUND Variants in dehydrodolichol diphosphate synthetase (DHDDS) and nuclear undecaprenyl pyrophosphate synthase 1 (NUS1) cause a neurodevelopmental disorder, classically with prominent epilepsy. Recent reports suggest a complex movement disorder and an overlapping phenotype has been postulated due to their combined role in dolichol synthesis. CASES We describe three patients with heterozygous variants in DHDDS and five with variants affecting NUS1. They bear a remarkably similar phenotype of a movement disorder dominated by multifocal myoclonus. Diagnostic clues include myoclonus exacerbated by action and facial involvement, and slowly progressive or stable, gait ataxia with disproportionately impaired tandem gait. Myoclonus is confirmed with neurophysiology, including EMG of facial muscles. LITERATURE REVIEW Ninety-eight reports of heterozygous variants in DHDDS, NUS1 and chromosome 6q22.1 structural alterations spanning NUS1, confirm the convergent phenotype of hypotonia at birth, developmental delay, multifocal myoclonus, ataxia, dystonia and later parkinsonism with or without generalized epilepsy. Other features include periodic exacerbations, stereotypies, anxiety, and dysmorphisms. Although their gene products contribute to dolichol biosynthesis, a key step in N-glycosylation, transferrin isoform profiles are typically normal. Imaging is normal or non-specific. CONCLUSIONS Recognition of their shared phenotype may expedite diagnosis through chromosomal microarray and by including DHDDS/NUS1 in movement disorder gene panels.
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Affiliation(s)
- Laura J. Williams
- Movement Disorder Unit, Department of NeurologyWestmead HospitalWestmeadNew South WalesAustralia
| | - Sophie Waller
- Movement Disorder Unit, Department of NeurologyWestmead HospitalWestmeadNew South WalesAustralia
| | - Jessica Qiu
- Movement Disorder Unit, Department of NeurologyWestmead HospitalWestmeadNew South WalesAustralia
| | - Emily Innes
- TY Nelson Department of Neurology and NeurosurgeryThe Children's Hospital at WestmeadWestmeadNew South WalesAustralia
- School of Medicine SydneyThe University of Notre DameSydneyNew South WalesAustralia
| | - Noha Elserafy
- Department of Genomic MedicineWestmead HospitalWestmeadNew South WalesAustralia
| | - Peter Procopis
- TY Nelson Department of Neurology and NeurosurgeryThe Children's Hospital at WestmeadWestmeadNew South WalesAustralia
- The Children's Hospital at Westmead Clinical School, Faculty of Medicine and HealthUniversity of SydneySydneyNew South WalesAustralia
| | - Hugo Sampaio
- Department of NeurologySydney Children's HospitalRandwickNew South WalesAustralia
- School of Women's and Children's HealthUniversity of New South WalesSydneyNew South WalesAustralia
| | - Neil Mahant
- Movement Disorder Unit, Department of NeurologyWestmead HospitalWestmeadNew South WalesAustralia
| | - Michel C. Tchan
- Department of Genomic MedicineWestmead HospitalWestmeadNew South WalesAustralia
- Specialty of Genomic Medicine, Faculty of Medicine and HealthThe University of SydneySydneyNew South WalesAustralia
| | - Shekeeb S. Mohammad
- TY Nelson Department of Neurology and NeurosurgeryThe Children's Hospital at WestmeadWestmeadNew South WalesAustralia
- Kids Neuroscience CentreThe Children's Hospital at WestmeadWestmeadNew South WalesAustralia
- Sydney Medical School, Faculty of Medicine and HealthUniversity of SydneySydneyNew South WalesAustralia
| | - Hugo Morales‐Briceño
- Movement Disorder Unit, Department of NeurologyWestmead HospitalWestmeadNew South WalesAustralia
| | - Victor S.C. Fung
- Movement Disorder Unit, Department of NeurologyWestmead HospitalWestmeadNew South WalesAustralia
- Sydney Medical School, Faculty of Medicine and HealthUniversity of SydneySydneyNew South WalesAustralia
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