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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 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
Increased Prevalence of Familial Autoimmune Disease in Children With Opsoclonus-Myoclonus Syndrome.
Santoro JD, Kerr LM, Codden R, Casper TC, Greenberg BM, Waubant E, Kong SW, Mandl KD, Gorman MP
Neurol Neuroimmunol Neuroinflamm 2021 Nov;8(6) Epub 2021 Sep 2 doi: 10.1212/NXI.0000000000001079. PMID: 34475249Free PMC Article
Carbamazepine-, Oxcarbazepine-, Eslicarbazepine-Associated Movement Disorder: A Literature Review.
Rissardo JP, Caprara ALF
Clin Neuropharmacol 2020 May/Jun;43(3):66-80. doi: 10.1097/WNF.0000000000000387. PMID: 32384309
Psychogenic movement disorders in children and adolescents: an update.
Harris SR
Eur J Pediatr 2019 Apr;178(4):581-585. Epub 2019 Jan 11 doi: 10.1007/s00431-019-03317-8. PMID: 30635706
The neurophysiological features of myoclonus-dystonia and differentiation from other dystonias.
Popa T, Milani P, Richard A, Hubsch C, Brochard V, Tranchant C, Sadnicka A, Rothwell J, Vidailhet M, Meunier S, Roze E
JAMA Neurol 2014 May;71(5):612-9. doi: 10.1001/jamaneurol.2014.99. PMID: 24638021

Diagnosis

Genetic Epilepsy Syndromes.
Myers KA
Continuum (Minneap Minn) 2022 Apr 1;28(2):339-362. doi: 10.1212/CON.0000000000001077. PMID: 35393962
Benign spasms of infancy: a mimicker of infantile epileptic disorders.
Ghossein J, Pohl D
Epileptic Disord 2019 Dec 1;21(6):585-589. doi: 10.1684/epd.2019.1116. PMID: 31843733
Familial adult myoclonic epilepsy: A new expansion repeats disorder.
Lagorio I, Zara F, Striano S, Striano P
Seizure 2019 Apr;67:73-77. Epub 2019 Mar 19 doi: 10.1016/j.seizure.2019.03.009. PMID: 30928698
Stiff person syndrome.
Duddy ME, Baker MR
Front Neurol Neurosci 2009;26:147-165. Epub 2009 Apr 6 doi: 10.1159/000212375. PMID: 19349711
Spinocerebellar ataxia 2 (SCA2).
Lastres-Becker I, Rüb U, Auburger G
Cerebellum 2008;7(2):115-24. doi: 10.1007/s12311-008-0019-y. PMID: 18418684

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
Topiramate-Associated Movement Disorder: Case Series and Literature Review.
Rissardo JP, Caprara ALF
Clin Neuropharmacol 2020 Jul/Aug;43(4):116-120. doi: 10.1097/WNF.0000000000000395. PMID: 32541330
Carbamazepine-, Oxcarbazepine-, Eslicarbazepine-Associated Movement Disorder: A Literature Review.
Rissardo JP, Caprara ALF
Clin Neuropharmacol 2020 May/Jun;43(3):66-80. doi: 10.1097/WNF.0000000000000387. PMID: 32384309
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

Prognosis

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
Genetic Epilepsy Syndromes.
Myers KA
Continuum (Minneap Minn) 2022 Apr 1;28(2):339-362. doi: 10.1212/CON.0000000000001077. PMID: 35393962
KCNN2 mutation in autosomal-dominant tremulous myoclonus-dystonia.
Balint B, Guerreiro R, Carmona S, Dehghani N, Latorre A, Cordivari C, Bhatia KP, Bras J
Eur J Neurol 2020 Aug;27(8):1471-1477. Epub 2020 May 3 doi: 10.1111/ene.14228. PMID: 32212350
Familial adult myoclonic epilepsy: A new expansion repeats disorder.
Lagorio I, Zara F, Striano S, Striano P
Seizure 2019 Apr;67:73-77. Epub 2019 Mar 19 doi: 10.1016/j.seizure.2019.03.009. PMID: 30928698
Stiff person syndrome.
Duddy ME, Baker MR
Front Neurol Neurosci 2009;26:147-165. Epub 2009 Apr 6 doi: 10.1159/000212375. PMID: 19349711

Clinical prediction guides

Myoclonus status revealing COVID 19 infection.
Ben Mohamed D, Zouari R, Ketata J, Nabli F, Blel S, Ben Sassi S
Seizure 2023 Jan;104:12-14. Epub 2022 Nov 22 doi: 10.1016/j.seizure.2022.11.010. PMID: 36446232Free PMC Article
KCNN2 mutation in autosomal-dominant tremulous myoclonus-dystonia.
Balint B, Guerreiro R, Carmona S, Dehghani N, Latorre A, Cordivari C, Bhatia KP, Bras J
Eur J Neurol 2020 Aug;27(8):1471-1477. Epub 2020 May 3 doi: 10.1111/ene.14228. PMID: 32212350
A new prion disease: relationship with central and peripheral amyloidoses.
Mead S, Reilly MM
Nat Rev Neurol 2015 Feb;11(2):90-7. Epub 2015 Jan 27 doi: 10.1038/nrneurol.2014.263. PMID: 25623792
Comparison of clinical characteristics between familial and non-familial early onset Alzheimer's disease.
Karve SJ, Ringman JM, Lee AS, Juarez KO, Mendez MF
J Neurol 2012 Oct;259(10):2182-8. Epub 2012 Mar 30 doi: 10.1007/s00415-012-6481-y. PMID: 22460587Free PMC Article
Spinocerebellar ataxia 2 (SCA2).
Lastres-Becker I, Rüb U, Auburger G
Cerebellum 2008;7(2):115-24. doi: 10.1007/s12311-008-0019-y. PMID: 18418684

Recent systematic reviews

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
Signs and symptoms preceding the diagnosis of Alzheimer's disease: a systematic scoping review of literature from 1937 to 2016.
Bature F, Guinn BA, Pang D, Pappas Y
BMJ Open 2017 Aug 28;7(8):e015746. doi: 10.1136/bmjopen-2016-015746. PMID: 28851777Free 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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