U.S. flag

An official website of the United States government

Format

Send to:

Choose Destination

Congenital myasthenic syndrome 20(CMS20)

MedGen UID:
934661
Concept ID:
C4310694
Disease or Syndrome
Synonym: Myasthenic syndrome, congenital, 20, presynaptic
 
Gene (location): SLC5A7 (2q12.3)
 
Monarch Initiative: MONDO:0014939
OMIM®: 617143

Definition

Congenital myasthenic syndrome-20 is an autosomal recessive neuromuscular disorder characterized by severe hypotonia associated with episodic apnea soon after birth. Patients have muscle weakness resulting in delayed walking, ptosis, poor sucking and swallowing, and generalized limb fatigability and weakness. EMG studies usually show a decremental response to repetitive nerve stimulation, and some patients may show a good response to AChE inhibitors (summary by Bauche et al., 2016). For a discussion of genetic heterogeneity of CMS, see CMS1A (601462). [from OMIM]

Clinical features

From HPO
Pes planus
MedGen UID:
42034
Concept ID:
C0016202
Anatomical Abnormality
A foot where the longitudinal arch of the foot is in contact with the ground or floor when the individual is standing; or, in a patient lying supine, a foot where the arch is in contact with the surface of a flat board pressed against the sole of the foot by the examiner with a pressure similar to that expected from weight bearing; or, the height of the arch is reduced.
Dysphagia
MedGen UID:
41440
Concept ID:
C0011168
Disease or Syndrome
Difficulty in swallowing.
Feeding difficulties
MedGen UID:
65429
Concept ID:
C0232466
Finding
Impaired ability to eat related to problems gathering food and getting ready to suck, chew, or swallow it.
Poor suck
MedGen UID:
324693
Concept ID:
C1837142
Finding
An inadequate sucking reflex, resulting in the difficult of newborns to be breast-fed.
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.
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.
Motor delay
MedGen UID:
381392
Concept ID:
C1854301
Finding
A type of Developmental delay characterized by a delay in acquiring motor skills.
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.
Bulbar palsy
MedGen UID:
898626
Concept ID:
C4082299
Disease or Syndrome
Bulbar weakness (or bulbar palsy) refers to bilateral impairment of function of the lower cranial nerves IX, X, XI and XII, which occurs due to lower motor neuron lesion either at nuclear or fascicular level in the medulla or from bilateral lesions of the lower cranial nerves outside the brain-stem. Bulbar weakness is often associated with difficulty in chewing, weakness of the facial muscles, dysarthria, palatal weakness and regurgitation of fluids, dysphagia, and dysphonia.
Kyphosis
MedGen UID:
44042
Concept ID:
C0022821
Anatomical Abnormality
Exaggerated anterior convexity of the thoracic vertebral column.
Hypotonia
MedGen UID:
10133
Concept ID:
C0026827
Finding
Hypotonia is an abnormally low muscle tone (the amount of tension or resistance to movement in a muscle). Even when relaxed, muscles have a continuous and passive partial contraction which provides some resistance to passive stretching. Hypotonia thus manifests as diminished resistance to passive stretching. Hypotonia is not the same as muscle weakness, although the two conditions can co-exist.
Scoliosis
MedGen UID:
11348
Concept ID:
C0036439
Disease or Syndrome
The presence of an abnormal lateral curvature of the spine.
Muscle weakness
MedGen UID:
57735
Concept ID:
C0151786
Finding
Reduced strength of muscles.
Proximal muscle weakness
MedGen UID:
113169
Concept ID:
C0221629
Finding
A lack of strength of the proximal muscles.
Neck muscle weakness
MedGen UID:
66808
Concept ID:
C0240479
Finding
Decreased strength of the neck musculature.
Facial palsy
MedGen UID:
87660
Concept ID:
C0376175
Disease or Syndrome
Facial nerve palsy is a dysfunction of cranial nerve VII (the facial nerve) that results in inability to control facial muscles on the affected side with weakness of the muscles of facial expression and eye closure. This can either be present in unilateral or bilateral form.
Muscular atrophy
MedGen UID:
892680
Concept ID:
C0541794
Pathologic Function
The presence of skeletal muscular atrophy (which is also known as amyotrophy).
Arthrogryposis multiplex congenita
MedGen UID:
1830310
Concept ID:
C5779613
Disease or Syndrome
Multiple congenital contractures in different body areas.
Apnea
MedGen UID:
2009
Concept ID:
C0003578
Sign or Symptom
Lack of breathing with no movement of the respiratory muscles and no exchange of air in the lungs. This term refers to a disposition to have recurrent episodes of apnea rather than to a single event.
Stridor
MedGen UID:
11613
Concept ID:
C0038450
Sign or Symptom
Stridor is a high pitched sound resulting from turbulent air flow in the upper airway.
Hypoventilation
MedGen UID:
469022
Concept ID:
C3203358
Pathologic Function
A reduction in the amount of air transported into the pulmonary alveoli by breathing, leading to hypercapnia (increase in the partial pressure of carbon dioxide).
Dysphonia
MedGen UID:
282893
Concept ID:
C1527344
Mental or Behavioral Dysfunction
Difficulty in speaking due to a physical disorder of the mouth, tongue, throat, or vocal cords. Associated with a known physical or neurological cause.
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).
Ophthalmoparesis
MedGen UID:
155551
Concept ID:
C0751401
Sign or Symptom
Ophthalmoplegia is a paralysis or weakness of one or more of the muscles that control eye movement.

Professional guidelines

PubMed

Daoud H, Luco SM, Li R, Bareke E, Beaulieu C, Jarinova O, Carson N, Nikkel SM, Graham GE, Richer J, Armour C, Bulman DE, Chakraborty P, Geraghty M, Lines MA, Lacaze-Masmonteil T, Majewski J, Boycott KM, Dyment DA
CMAJ 2016 Aug 9;188(11):E254-E260. Epub 2016 May 30 doi: 10.1503/cmaj.150823. PMID: 27241786Free PMC Article
Robb SA, Muntoni F, Simonds AK
Neuromuscul Disord 2010 Dec;20(12):833-8. Epub 2010 Sep 17 doi: 10.1016/j.nmd.2010.08.002. PMID: 20850318

Recent clinical studies

Etiology

Krenn M, Sener M, Rath J, Zulehner G, Keritam O, Wagner M, Laccone F, Iglseder S, Marte S, Baumgartner M, Eisenkölbl A, Liechtenstein C, Rudnik S, Quasthoff S, Grinzinger S, Spenger J, Wortmann SB, Löscher WN, Zimprich F, Kellersmann A, Rappold M, Bernert G, Freilinger M, Cetin H
J Neurol 2023 Feb;270(2):909-916. Epub 2022 Oct 29 doi: 10.1007/s00415-022-11440-0. PMID: 36308527Free PMC Article
Vianello A, Racca F, Vita GL, Pierucci P, Vita G
Handb Clin Neurol 2022;189:259-270. doi: 10.1016/B978-0-323-91532-8.00014-8. PMID: 36031308
Megarbane A, Bizzari S, Deepthi A, Sabbagh S, Mansour H, Chouery E, Hmaimess G, Jabbour R, Mehawej C, Alame S, Hani A, Hasbini D, Ghanem I, Koussa S, Al-Ali MT, Obeid M, Talea DB, Lefranc G, Lévy N, Leturcq F, El Hayek S, Delague V, Urtizberea JA
J Neuromuscul Dis 2022;9(1):193-210. doi: 10.3233/JND-210652. PMID: 34602496Free PMC Article
Finsterer J
Orphanet J Rare Dis 2019 Feb 26;14(1):57. doi: 10.1186/s13023-019-1025-5. PMID: 30808424Free PMC Article
Belaya K, Rodríguez Cruz PM, Liu WW, Maxwell S, McGowan S, Farrugia ME, Petty R, Walls TJ, Sedghi M, Basiri K, Yue WW, Sarkozy A, Bertoli M, Pitt M, Kennett R, Schaefer A, Bushby K, Parton M, Lochmüller H, Palace J, Muntoni F, Beeson D
Brain 2015 Sep;138(Pt 9):2493-504. Epub 2015 Jun 30 doi: 10.1093/brain/awv185. PMID: 26133662Free PMC Article

Diagnosis

Krenn M, Sener M, Rath J, Zulehner G, Keritam O, Wagner M, Laccone F, Iglseder S, Marte S, Baumgartner M, Eisenkölbl A, Liechtenstein C, Rudnik S, Quasthoff S, Grinzinger S, Spenger J, Wortmann SB, Löscher WN, Zimprich F, Kellersmann A, Rappold M, Bernert G, Freilinger M, Cetin H
J Neurol 2023 Feb;270(2):909-916. Epub 2022 Oct 29 doi: 10.1007/s00415-022-11440-0. PMID: 36308527Free PMC Article
Yoganathan K, Stevenson A, Tahir A, Sadler R, Radunovic A, Malek N
J Neurol 2022 Jun;269(6):3372-3384. Epub 2022 Feb 10 doi: 10.1007/s00415-022-10986-3. PMID: 35142871Free PMC Article
Megarbane A, Bizzari S, Deepthi A, Sabbagh S, Mansour H, Chouery E, Hmaimess G, Jabbour R, Mehawej C, Alame S, Hani A, Hasbini D, Ghanem I, Koussa S, Al-Ali MT, Obeid M, Talea DB, Lefranc G, Lévy N, Leturcq F, El Hayek S, Delague V, Urtizberea JA
J Neuromuscul Dis 2022;9(1):193-210. doi: 10.3233/JND-210652. PMID: 34602496Free PMC Article
Finsterer J
Orphanet J Rare Dis 2019 Feb 26;14(1):57. doi: 10.1186/s13023-019-1025-5. PMID: 30808424Free PMC Article
Belaya K, Rodríguez Cruz PM, Liu WW, Maxwell S, McGowan S, Farrugia ME, Petty R, Walls TJ, Sedghi M, Basiri K, Yue WW, Sarkozy A, Bertoli M, Pitt M, Kennett R, Schaefer A, Bushby K, Parton M, Lochmüller H, Palace J, Muntoni F, Beeson D
Brain 2015 Sep;138(Pt 9):2493-504. Epub 2015 Jun 30 doi: 10.1093/brain/awv185. PMID: 26133662Free PMC Article

Therapy

Akkol EK, Karatoprak GŞ, Carpar E, Hussain Y, Khan H, Aschner M
Curr Neuropharmacol 2022 Mar 4;20(3):594-610. doi: 10.2174/1570159X19666210924092627. PMID: 34561984Free PMC Article
Rodríguez Cruz PM, Hughes I, Manzur A, Munot P, Ramdas S, Wright R, Breen C, Pitt M, Pagnamenta AT, Taylor JC, Palace J, Beeson D
Neuromuscul Disord 2021 Jan;31(1):21-28. Epub 2020 Oct 20 doi: 10.1016/j.nmd.2020.10.006. PMID: 33250374
Finsterer J
Orphanet J Rare Dis 2019 Feb 26;14(1):57. doi: 10.1186/s13023-019-1025-5. PMID: 30808424Free PMC Article
Mihaylova V, Müller JS, Vilchez JJ, Salih MA, Kabiraj MM, D'Amico A, Bertini E, Wölfle J, Schreiner F, Kurlemann G, Rasic VM, Siskova D, Colomer J, Herczegfalvi A, Fabriciova K, Weschke B, Scola R, Hoellen F, Schara U, Abicht A, Lochmüller H
Brain 2008 Mar;131(Pt 3):747-59. Epub 2008 Jan 7 doi: 10.1093/brain/awm325. PMID: 18180250
Mullaney P, Vajsar J, Smith R, Buncic JR
Ophthalmology 2000 Mar;107(3):504-10. doi: 10.1016/s0161-6420(99)00138-4. PMID: 10711889

Prognosis

Vlckova M, Prchalova D, Zimmermann P, Haberlova J, Bendova S, Moslerova V, Stranecky V, Sedlacek Z, Hancarova M
Mol Genet Genomic Med 2023 Jun;11(6):e2154. Epub 2023 Feb 24 doi: 10.1002/mgg3.2154. PMID: 36840359Free PMC Article
Vianello A, Racca F, Vita GL, Pierucci P, Vita G
Handb Clin Neurol 2022;189:259-270. doi: 10.1016/B978-0-323-91532-8.00014-8. PMID: 36031308
Rodríguez Cruz PM, Hughes I, Manzur A, Munot P, Ramdas S, Wright R, Breen C, Pitt M, Pagnamenta AT, Taylor JC, Palace J, Beeson D
Neuromuscul Disord 2021 Jan;31(1):21-28. Epub 2020 Oct 20 doi: 10.1016/j.nmd.2020.10.006. PMID: 33250374
Mihaylova V, Müller JS, Vilchez JJ, Salih MA, Kabiraj MM, D'Amico A, Bertini E, Wölfle J, Schreiner F, Kurlemann G, Rasic VM, Siskova D, Colomer J, Herczegfalvi A, Fabriciova K, Weschke B, Scola R, Hoellen F, Schara U, Abicht A, Lochmüller H
Brain 2008 Mar;131(Pt 3):747-59. Epub 2008 Jan 7 doi: 10.1093/brain/awm325. PMID: 18180250
Engel AG
Ann Neurol 1984 Nov;16(5):519-34. doi: 10.1002/ana.410160502. PMID: 6095730

Clinical prediction guides

Vlckova M, Prchalova D, Zimmermann P, Haberlova J, Bendova S, Moslerova V, Stranecky V, Sedlacek Z, Hancarova M
Mol Genet Genomic Med 2023 Jun;11(6):e2154. Epub 2023 Feb 24 doi: 10.1002/mgg3.2154. PMID: 36840359Free PMC Article
Caggiano S, Khirani S, Verrillo E, Barnerias C, Amaddeo A, Gitiaux C, Thierry B, Desguerre I, Cutrera R, Fauroux B
Eur J Paediatr Neurol 2017 Nov;21(6):842-851. Epub 2017 Jul 21 doi: 10.1016/j.ejpn.2017.07.010. PMID: 28755803
Laforêt P, Vianey-Saban C
Neuromuscul Disord 2010 Nov;20(11):693-700. Epub 2010 Aug 5 doi: 10.1016/j.nmd.2010.06.018. PMID: 20691590
Mihaylova V, Müller JS, Vilchez JJ, Salih MA, Kabiraj MM, D'Amico A, Bertini E, Wölfle J, Schreiner F, Kurlemann G, Rasic VM, Siskova D, Colomer J, Herczegfalvi A, Fabriciova K, Weschke B, Scola R, Hoellen F, Schara U, Abicht A, Lochmüller H
Brain 2008 Mar;131(Pt 3):747-59. Epub 2008 Jan 7 doi: 10.1093/brain/awm325. PMID: 18180250
Engel AG
Ann Neurol 1984 Nov;16(5):519-34. doi: 10.1002/ana.410160502. PMID: 6095730

Recent systematic reviews

Finsterer J
Orphanet J Rare Dis 2019 Feb 26;14(1):57. doi: 10.1186/s13023-019-1025-5. PMID: 30808424Free PMC Article

Supplemental Content

Table of contents

    Clinical resources

    Practice guidelines

    • PubMed
      See practice and clinical guidelines in PubMed. The search results may include broader topics and may not capture all published guidelines. See the FAQ for details.

    Recent activity

    Your browsing activity is empty.

    Activity recording is turned off.

    Turn recording back on

    See more...