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Congenital myasthenic syndrome 18(CMS18)

MedGen UID:
906793
Concept ID:
C4225364
Disease or Syndrome
Synonym: MYASTHENIC SYNDROME, CONGENITAL, 18, WITH INTELLECTUAL DISABILITY AND ATAXIA
 
Gene (location): SNAP25 (20p12.2)
 
Monarch Initiative: MONDO:0014590
OMIM®: 616330

Definition

Congenital myasthenic syndrome-18 (CMS18) is an autosomal dominant presynaptic neuromuscular disorder characterized by early-onset muscle weakness and easy fatigability associated with delayed psychomotor development and ataxia (summary by Shen et al., 2014). For a discussion of genetic heterogeneity of CMS, see CMS1A (601462). [from OMIM]

Clinical features

From HPO
Knee flexion contracture
MedGen UID:
98042
Concept ID:
C0409355
Finding
A type of knee joint contracture in which the knee is in a fixed bent (flexed) configuration such that it cannot be straightened actively or passively.
Cerebellar ataxia
MedGen UID:
849
Concept ID:
C0007758
Disease or Syndrome
Cerebellar ataxia refers to ataxia due to dysfunction of the cerebellum. This causes a variety of elementary neurological deficits including asynergy (lack of coordination between muscles, limbs and joints), dysmetria (lack of ability to judge distances that can lead to under- or overshoot in grasping movements), and dysdiadochokinesia (inability to perform rapid movements requiring antagonizing muscle groups to be switched on and off repeatedly).
Dysarthria
MedGen UID:
8510
Concept ID:
C0013362
Mental or Behavioral Dysfunction
Dysarthric speech is a general description referring to a neurological speech disorder characterized by poor articulation. Depending on the involved neurological structures, dysarthria may be further classified as spastic, flaccid, ataxic, hyperkinetic and hypokinetic, or mixed.
Echolalia
MedGen UID:
8532
Concept ID:
C0013528
Mental or Behavioral Dysfunction
Echolalia is the automatic imitative repetition of sounds, words, or phrases in the absence of explicit awareness. The repeated words or phrases are typically odd or used in a non-social manner. These can be words or phrases that the affected individual has heard or invented.
Areflexia
MedGen UID:
115943
Concept ID:
C0234146
Finding
Absence of neurologic reflexes such as the knee-jerk reaction.
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.
Global developmental delay
MedGen UID:
107838
Concept ID:
C0557874
Finding
A delay in the achievement of motor or mental milestones in the domains of development of a child, including motor skills, speech and language, cognitive skills, and social and emotional skills. This term should only be used to describe children younger than five years of age.
Fatigable weakness
MedGen UID:
451076
Concept ID:
C0947912
Disease or Syndrome
A type of weakness that occurs after a muscle group is used and lessens if the muscle group has some rest. That is, there is diminution of strength with repetitive muscle actions.
Poor speech
MedGen UID:
341172
Concept ID:
C1848207
Finding
Difficulty walking
MedGen UID:
86319
Concept ID:
C0311394
Finding
Reduced ability to walk (ambulate).
Neonatal respiratory distress
MedGen UID:
924182
Concept ID:
C4281993
Finding
Respiratory difficulty as newborn.
Decreased fetal movement
MedGen UID:
68618
Concept ID:
C0235659
Finding
An abnormal reduction in quantity or strength of fetal movements.
Ptosis
MedGen UID:
2287
Concept ID:
C0005745
Disease or Syndrome
The upper eyelid margin is positioned 3 mm or more lower than usual and covers the superior portion of the iris (objective); or, the upper lid margin obscures at least part of the pupil (subjective).

Professional guidelines

PubMed

Lu M, Reisch J, Iannaccone S, Batley K
Pediatr Neurol 2024 Jul;156:10-14. Epub 2024 Mar 24 doi: 10.1016/j.pediatrneurol.2024.03.019. PMID: 38688232
Yildiz EP, Kilic MA, Yalcin EU, Kurekci F, Avci R, Hacıfazlıoğlu NE, Ceylaner S, Gezdirici A, Çalışkan M
Acta Neurol Belg 2023 Oct;123(5):1841-1847. Epub 2022 Sep 12 doi: 10.1007/s13760-022-02090-0. PMID: 36094697
Witting N, Vissing J
JAMA Neurol 2014 Mar;71(3):350-4. doi: 10.1001/jamaneurol.2013.5590. PMID: 24425145

Recent clinical studies

Etiology

Jühlen R, Grauer L, Martinelli V, Rencurel C, Fahrenkrog B
Sci Rep 2024 Jan 19;14(1):1742. doi: 10.1038/s41598-023-50615-1. PMID: 38242956Free PMC Article
Zhao Y, Li Y, Bian Y, Yao S, Liu P, Yu M, Zhang W, Wang Z, Yuan Y
Ann Clin Transl Neurol 2021 Apr;8(4):898-907. Epub 2021 Mar 23 doi: 10.1002/acn3.51346. PMID: 33756069Free PMC Article
Hoei-Hansen CE, Tygesen MLB, Dunø M, Vissing J, Ballegaard M, Born AP
Neuropediatrics 2021 Dec;52(6):462-468. Epub 2021 Mar 11 doi: 10.1055/s-0041-1726120. PMID: 33706403
Prior DE, Ghosh PS
J Child Neurol 2021 Jul;36(8):610-617. Epub 2021 Jan 20 doi: 10.1177/0883073820987755. PMID: 33471587
Eymard B, Hantaï D, Estournet B
Handb Clin Neurol 2013;113:1469-80. doi: 10.1016/B978-0-444-59565-2.00016-2. PMID: 23622369

Diagnosis

Allen NM, O'Rahelly M, Eymard B, Chouchane M, Hahn A, Kearns G, Kim DS, Byun SY, Nguyen CE, Schara-Schmidt U, Kölbel H, Marina AD, Schneider-Gold C, Roefke K, Thieme A, Van den Bergh P, Avalos G, Álvarez-Velasco R, Natera-de Benito D, Cheng MHM, Chan WK, Wan HS, Thomas MA, Borch L, Lauzon J, Kornblum C, Reimann J, Mueller A, Kuntzer T, Norwood F, Ramdas S, Jacobson LW, Jie X, Fernandez-Garcia MA, Wraige E, Lim M, Lin JP, Claeys KG, Aktas S, Oskoui M, Hacohen Y, Masud A, Leite MI, Palace J, De Vivo D, Vincent A, Jungbluth H
Brain 2023 Oct 3;146(10):4233-4246. doi: 10.1093/brain/awad153. PMID: 37186601Free PMC Article
Zhao Y, Li Y, Bian Y, Yao S, Liu P, Yu M, Zhang W, Wang Z, Yuan Y
Ann Clin Transl Neurol 2021 Apr;8(4):898-907. Epub 2021 Mar 23 doi: 10.1002/acn3.51346. PMID: 33756069Free PMC Article
Engel AG
Curr Neurol Neurosci Rep 2018 Jun 12;18(8):46. doi: 10.1007/s11910-018-0852-4. PMID: 29892917
Eymard B, Hantaï D, Estournet B
Handb Clin Neurol 2013;113:1469-80. doi: 10.1016/B978-0-444-59565-2.00016-2. PMID: 23622369
Rabie M, Jossiphov J, Nevo Y
J Child Neurol 2007 Jul;22(7):803-8. doi: 10.1177/0883073807304204. PMID: 17715269

Therapy

Hesami O, Ramezani M, Ghasemi A, Fatehi F, Okhovat AA, Ziaadini B, Kariminejad A, Nafissi S
Orphanet J Rare Dis 2024 Mar 12;19(1):113. doi: 10.1186/s13023-024-03116-x. PMID: 38475910Free PMC Article
McMacken G, Whittaker RG, Evangelista T, Abicht A, Dusl M, Lochmüller H
J Neurol 2018 Jan;265(1):194-203. Epub 2017 Nov 30 doi: 10.1007/s00415-017-8689-3. PMID: 29189923Free PMC Article
Burke G, Cossins J, Maxwell S, Robb S, Nicolle M, Vincent A, Newsom-Davis J, Palace J, Beeson D
Neuromuscul Disord 2004 Jun;14(6):356-64. doi: 10.1016/j.nmd.2004.03.005. PMID: 15145336
Abicht A, Müller-Felber W, Fischer P, Jakob I, Kürz L, Rudel R, Mortier W, Pongratz D, Lochmüller H
Eur J Med Res 1997 Dec 31;2(12):515-22. PMID: 9498929

Prognosis

Yildiz EP, Kilic MA, Yalcin EU, Kurekci F, Avci R, Hacıfazlıoğlu NE, Ceylaner S, Gezdirici A, Çalışkan M
Acta Neurol Belg 2023 Oct;123(5):1841-1847. Epub 2022 Sep 12 doi: 10.1007/s13760-022-02090-0. PMID: 36094697
Zhao Y, Li Y, Bian Y, Yao S, Liu P, Yu M, Zhang W, Wang Z, Yuan Y
Ann Clin Transl Neurol 2021 Apr;8(4):898-907. Epub 2021 Mar 23 doi: 10.1002/acn3.51346. PMID: 33756069Free PMC Article
AlTaisan A, Magliyah M, Abouammoh MA, Taskintuna I, Alzahrani Y, Chang E, Alsulaiman SM
Ophthalmic Surg Lasers Imaging Retina 2020 Nov 1;51(11):618-627. doi: 10.3928/23258160-20201104-03. PMID: 33231694
Liu Y, Wu W, Huang Q
Int J Pediatr Otorhinolaryngol 2020 Dec;139:110465. Epub 2020 Oct 23 doi: 10.1016/j.ijporl.2020.110465. PMID: 33120102
Parr JR, Andrew MJ, Finnis M, Beeson D, Vincent A, Jayawant S
Arch Dis Child 2014 Jun;99(6):539-42. Epub 2014 Feb 5 doi: 10.1136/archdischild-2013-304788. PMID: 24500997

Clinical prediction guides

Lu M, Reisch J, Iannaccone S, Batley K
Pediatr Neurol 2024 Jul;156:10-14. Epub 2024 Mar 24 doi: 10.1016/j.pediatrneurol.2024.03.019. PMID: 38688232
Zhao Y, Li Y, Bian Y, Yao S, Liu P, Yu M, Zhang W, Wang Z, Yuan Y
Ann Clin Transl Neurol 2021 Apr;8(4):898-907. Epub 2021 Mar 23 doi: 10.1002/acn3.51346. PMID: 33756069Free PMC Article
Prior DE, Cooper BA, Zhang B, Ghosh PS
Muscle Nerve 2021 May;63(5):751-757. Epub 2021 Feb 28 doi: 10.1002/mus.27208. PMID: 33604899
McMacken G, Whittaker RG, Evangelista T, Abicht A, Dusl M, Lochmüller H
J Neurol 2018 Jan;265(1):194-203. Epub 2017 Nov 30 doi: 10.1007/s00415-017-8689-3. PMID: 29189923Free PMC Article
Engel AG, Shen XM, Selcen D, Sine SM
J Mol Neurosci 2010 Jan;40(1-2):143-53. Epub 2009 Aug 18 doi: 10.1007/s12031-009-9229-0. PMID: 19688192Free PMC Article

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