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Myoclonus, familial, 2(MYOCL2)

MedGen UID:
1683864
•Concept ID:
C5193056
•
Disease or Syndrome
Synonyms: MYOCL2; MYOCLONUS, FAMILIAL, 2
 
Gene (location): SCN8A (12q13.13)
 
Monarch Initiative: MONDO:0100092
OMIM®: 618364

Definition

Familial myoclonus-2 (MYOCL2) is an autosomal dominant neurologic condition characterized by childhood onset of isolated action-induced nonepileptic myoclonus affecting the upper limbs. The disorder is nonprogressive (Wagnon et al., 2018). [from OMIM]

Clinical features

From HPO
Dystonic disorder
MedGen UID:
3940
•Concept ID:
C0013421
•
Sign or Symptom
An abnormally increased muscular tone that causes fixed abnormal postures. There is a slow, intermittent twisting motion that leads to exaggerated turning and posture of the extremities and trunk.
See: Feature record | Search on this feature
Seizure
MedGen UID:
20693
•Concept ID:
C0036572
•
Sign or Symptom
A seizure is an intermittent abnormality of nervous system physiology characterized by a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain.
See: Feature record | Search on this feature
Delayed ability to walk
MedGen UID:
66034
•Concept ID:
C0241726
•
Finding
A failure to achieve the ability to walk at an appropriate developmental stage. Most children learn to walk in a series of stages, and learn to walk short distances independently between 12 and 15 months.
See: Feature record | Search on this feature
Intellectual disability
MedGen UID:
811461
•Concept ID:
C3714756
•
Mental or Behavioral Dysfunction
Intellectual disability, previously referred to as mental retardation, is characterized by subnormal intellectual functioning that occurs during the developmental period. It is defined by an IQ score below 70.
See: Feature record | Search on this feature
Limb myoclonus
MedGen UID:
1368754
•Concept ID:
C4477055
•
Sign or Symptom
See: Feature record | Search on this feature

Professional guidelines

PubMed

Phenotypic and genetic spectrum of SCN8A-related disorders, treatment options, and outcomes.
Gardella E, Møller RS
Epilepsia 2019 Dec;60 Suppl 3:S77-S85. doi: 10.1111/epi.16319. PMID: 31904124
Unverricht-Lundborg disease: Clinical course and seizure management based on the experience of polish centers.
Lasek-Bal A, Lukasik M, Żak A, Sulek A, Bosak M
Seizure 2019 Jul;69:87-91. Epub 2019 Apr 10 doi: 10.1016/j.seizure.2019.04.008. PMID: 30999254
Diagnosis and management of restless legs syndrome in children.
Simakajornboon N, Kheirandish-Gozal L, Gozal D
Sleep Med Rev 2009 Apr;13(2):149-56. Epub 2009 Jan 31 doi: 10.1016/j.smrv.2008.12.002. PMID: 19186083Free PMC Article

Recent clinical studies

Etiology

A comprehensive narrative review of epilepsy with eyelid myoclonia.
Smith KM, Wirrell EC, Andrade DM, Choi H, Trenité DK, Knupp KG, Nordli DR Jr, Riva A, Stern JM, Striano P, Thiele EA, Zawar I
Epilepsy Res 2023 Jul;193:107147. Epub 2023 Apr 26 doi: 10.1016/j.eplepsyres.2023.107147. PMID: 37121024
Parental symptom report and periodic limb movements of sleep in children.
Martin BT, Williamson BD, Edwards N, Teng AY
J Clin Sleep Med 2008 Feb 15;4(1):57-61. PMID: 18350964Free PMC Article
Clinical-electrophysiological correlation of tremor and myoclonus in a kindred with the N279K tau mutation.
Caviness JN, Tsuboi Y, Wszolek ZK
Parkinsonism Relat Disord 2003 Jan;9(3):151-7. doi: 10.1016/s1353-8020(02)00034-2. PMID: 12573870
Eye closure related spike and wave discharges: clinical and syndromic associations.
Baykan-Kurt B, Gökyiğit A, Parman Y, Kinay D, Gürses C
Clin Electroencephalogr 1999 Jul;30(3):106-10. doi: 10.1177/155005949903000306. PMID: 10578473
A retrospective study of Creutzfeldt-Jakob disease in Italy (1972-1986).
Masullo C, Pocchiari M, Neri G, Casaccia P, Iavarone A, Ladogana A, Macchi G
Eur J Epidemiol 1988 Dec;4(4):482-7. doi: 10.1007/BF00146403. PMID: 3060369

Diagnosis

Genetic Epilepsy Syndromes.
Myers KA
Continuum (Minneap Minn) 2022 Apr 1;28(2):339-362. doi: 10.1212/CON.0000000000001077. PMID: 35393962
Genetic Aspects of Myoclonus-Dystonia Syndrome (MDS).
Rachad L, El Kadmiri N, Slassi I, El Otmani H, Nadifi S
Mol Neurobiol 2017 Mar;54(2):939-942. Epub 2016 Jan 20 doi: 10.1007/s12035-016-9712-x. PMID: 26790671
Intractable absence seizures in hyperinsulinism-hyperammonemia syndrome.
Nakano K, Kobayashi K, Okano Y, Aso K, Ohtsuka Y
Pediatr Neurol 2012 Aug;47(2):119-22. doi: 10.1016/j.pediatrneurol.2012.04.019. PMID: 22759688
Stiff person syndrome.
Duddy ME, Baker MR
Front Neurol Neurosci 2009;26:147-165. Epub 2009 Apr 6 doi: 10.1159/000212375. PMID: 19349711
Inherited movement disorders.
Harding AE
Baillieres Clin Neurol 1994 Aug;3(2):259-79. PMID: 7952847

Therapy

A comprehensive narrative review of epilepsy with eyelid myoclonia.
Smith KM, Wirrell EC, Andrade DM, Choi H, Trenité DK, Knupp KG, Nordli DR Jr, Riva A, Stern JM, Striano P, Thiele EA, Zawar I
Epilepsy Res 2023 Jul;193:107147. Epub 2023 Apr 26 doi: 10.1016/j.eplepsyres.2023.107147. PMID: 37121024
Movement disorders associated with neuronal antibodies: a data-driven approach.
Sturchio A, Dwivedi AK, Gastaldi M, Grimberg MB, Businaro P, Duque KR, Vizcarra JA, Abdelghany E, Balint B, Marsili L, Espay AJ
J Neurol 2022 Jul;269(7):3511-3521. Epub 2022 Jan 13 doi: 10.1007/s00415-021-10934-7. PMID: 35024921Free PMC Article
Beneficial Effects of Metformin on the Central Nervous System, with a Focus on Epilepsy and Lafora Disease.
Sanz P, Serratosa JM, Sánchez MP
Int J Mol Sci 2021 May 19;22(10) doi: 10.3390/ijms22105351. PMID: 34069559Free PMC Article
Movement disorders and other motor abnormalities in adults with 22q11.2 deletion syndrome.
Boot E, Butcher NJ, van Amelsvoort TA, Lang AE, Marras C, Pondal M, Andrade DM, Fung WL, Bassett AS
Am J Med Genet A 2015 Mar;167A(3):639-45. Epub 2015 Feb 13 doi: 10.1002/ajmg.a.36928. PMID: 25684639Free PMC Article
Antidepressants and the serotonin syndrome in general practice.
Mackay FJ, Dunn NR, Mann RD
Br J Gen Pract 1999 Nov;49(448):871-4. PMID: 10818650Free PMC Article

Prognosis

Loss-of-function mutations in SGCE found in Japanese patients with myoclonus-dystonia.
Azuma K, Horisawa S, Mashimo H, Fukuda M, Kumada S, Kawamata T, Taira T, Akagawa H
Clin Genet 2023 Feb;103(2):209-213. Epub 2022 Oct 7 doi: 10.1111/cge.14233. PMID: 36161439
Genetic Epilepsy Syndromes.
Myers KA
Continuum (Minneap Minn) 2022 Apr 1;28(2):339-362. doi: 10.1212/CON.0000000000001077. PMID: 35393962
ADCY5-related dyskinesia presenting as familial myoclonus-dystonia.
Douglas AG, Andreoletti G, Talbot K, Hammans SR, Singh J, Whitney A, Ennis S, Foulds NC
Neurogenetics 2017 Apr;18(2):111-117. Epub 2017 Feb 22 doi: 10.1007/s10048-017-0510-z. PMID: 28229249Free PMC Article
Stiff person syndrome.
Duddy ME, Baker MR
Front Neurol Neurosci 2009;26:147-165. Epub 2009 Apr 6 doi: 10.1159/000212375. PMID: 19349711
Inherited movement disorders.
Harding AE
Baillieres Clin Neurol 1994 Aug;3(2):259-79. PMID: 7952847

Clinical prediction guides

Movement Disorders in Patients With Genetic Developmental and Epileptic Encephalopathies.
van der Veen S, Tse GTW, Ferretti A, Garone G, Post B, Specchio N, Fung VSC, Trivisano M, Scheffer IE
Neurology 2023 Nov 7;101(19):e1884-e1892. Epub 2023 Sep 25 doi: 10.1212/WNL.0000000000207808. PMID: 37748886Free PMC Article
Loss-of-function mutations in SGCE found in Japanese patients with myoclonus-dystonia.
Azuma K, Horisawa S, Mashimo H, Fukuda M, Kumada S, Kawamata T, Taira T, Akagawa H
Clin Genet 2023 Feb;103(2):209-213. Epub 2022 Oct 7 doi: 10.1111/cge.14233. PMID: 36161439
ADCY5-related dyskinesia presenting as familial myoclonus-dystonia.
Douglas AG, Andreoletti G, Talbot K, Hammans SR, Singh J, Whitney A, Ennis S, Foulds NC
Neurogenetics 2017 Apr;18(2):111-117. Epub 2017 Feb 22 doi: 10.1007/s10048-017-0510-z. PMID: 28229249Free PMC Article
Progressive myoclonus epilepsy with nephropathy C1q due to SCARB2/LIMP-2 deficiency: clinical report of two siblings.
Chaves J, Beirão I, Balreira A, Gaspar P, Caiola D, Sá-Miranda MC, Lima JL
Seizure 2011 Nov;20(9):738-40. Epub 2011 Jul 22 doi: 10.1016/j.seizure.2011.06.018. PMID: 21782476
Inherited movement disorders.
Harding AE
Baillieres Clin Neurol 1994 Aug;3(2):259-79. PMID: 7952847

Recent systematic reviews

KCTD7-related progressive myoclonic epilepsy: Report of 42 cases and review of literature.
Yoganathan S, Whitney R, Thomas M, Danda S, Chettali AM, Prasad AN, Farhan SMK, AlSowat D, Abukhaled M, Aldhalaan H, Gowda VK, Kinhal UV, Bylappa AY, Konanki R, Lingappa L, Parchuri BM, Appendino JP, Scantlebury MH, Cunningham J, Hadjinicolaou A, El Achkar CM, Kamate M, Menon RN, Jose M, Riordan G, Kannan L, Jain V, Manokaran RK, Chau V, Donner EJ, Costain G, Minassian BA, Jain P
Epilepsia 2024 Mar;65(3):709-724. Epub 2024 Jan 17 doi: 10.1111/epi.17880. PMID: 38231304
Geniospasm: A systematic review on natural history, prognosis, and treatment.
Teng LY, Abd Hadi D, Anandakrishnan P, Murugesu S, Khoo TB, Mohamed AR
Brain Dev 2022 Sep;44(8):499-511. Epub 2022 Jun 4 doi: 10.1016/j.braindev.2022.05.005. PMID: 35672188
Movement disorders associated with neuronal antibodies: a data-driven approach.
Sturchio A, Dwivedi AK, Gastaldi M, Grimberg MB, Businaro P, Duque KR, Vizcarra JA, Abdelghany E, Balint B, Marsili L, Espay AJ
J Neurol 2022 Jul;269(7):3511-3521. Epub 2022 Jan 13 doi: 10.1007/s00415-021-10934-7. PMID: 35024921Free PMC Article
Movement Disorders in Prionopathies: A Systematic Review.
Rodriguez-Porcel F, Ciarlariello VB, Dwivedi AK, Lovera L, Da Prat G, Lopez-Castellanos R, Suri R, Laub H, Walker RH, Barsottini O, Pedroso JL, Espay AJ
Tremor Other Hyperkinet Mov (N Y) 2019;9 Epub 2019 Dec 12 doi: 10.7916/tohm.v0.712. PMID: 31871824Free PMC Article
A systematic review of familial Alzheimer's disease: Differences in presentation of clinical features among three mutated genes and potential ethnic differences.
Shea YF, Chu LW, Chan AO, Ha J, Li Y, Song YQ
J Formos Med Assoc 2016 Feb;115(2):67-75. Epub 2015 Aug 31 doi: 10.1016/j.jfma.2015.08.004. PMID: 26337232

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      OMIM records containing genes associated with phenotypes registered in MedGen
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