Hostname: page-component-cd9895bd7-jn8rn Total loading time: 0 Render date: 2024-12-23T07:46:01.999Z Has data issue: false hasContentIssue false

Congenital myasthenic syndromes: spotlight on genetic defects of neuromuscular transmission

Published online by Cambridge University Press:  09 August 2007

Juliane S Müller
Affiliation:
Friedrich-Baur-Institute, Department of Neurology, Ludwig-Maximilians-University, Munich, Germany. Present address: Institute of Human Genetics, University of Newcastle upon Tyne, UK.
Violeta Mihaylova
Affiliation:
Friedrich-Baur-Institute, Department of Neurology, Ludwig-Maximilians-University, Munich, Germany.
Angela Abicht
Affiliation:
Friedrich-Baur-Institute, Department of Neurology, Ludwig-Maximilians-University, Munich, Germany.
Hanns Lochmüller*
Affiliation:
Friedrich-Baur-Institute, Department of Neurology, Ludwig-Maximilians-University, Munich, Germany.
*
*Corresponding author: Hanns Lochmüller, Friedrich-Baur-Institute, Molecular Myology Laboratory, Marchioninistrasse 17, 81377 München, Germany. Tel: +49 89 2180 78180; Fax: +49 89 2180 78184; E-mail: [email protected]

Abstract

The neuromuscular junction (NMJ) is a complex structure that efficiently communicates the electrical impulse from the motor neuron to the skeletal muscle to induce muscle contraction. Genetic and autoimmune disorders known to compromise neuromuscular transmission are providing further insights into the complexities of NMJ function. Congenital myasthenic syndromes (CMSs) are a genetically and phenotypically heterogeneous group of rare hereditary disorders affecting neuromuscular transmission. The understanding of the molecular basis of the different types of CMSs has evolved rapidly in recent years. Mutations were first identified in the subunits of the nicotinic acetylcholine receptor (AChR), but now mutations in ten different genes – encoding post-, pre- or synaptic proteins – are known to cause CMSs. Pathogenic mechanisms leading to an impaired neuromuscular transmission modify AChRs or endplate structure or lead to decreased acetylcholine synthesis and release. However, the genetic background of many CMS forms is still unresolved. A precise molecular classification of CMS type is of paramount importance for the diagnosis, counselling and therapy of a patient, as different drugs may be beneficial or deleterious depending on the molecular background of the particular CMS.

Type
Review Article
Copyright
Copyright © Cambridge University Press 2007

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

References

1Vincent, A. et al. (1981) Congenital myasthenia: end-plate acetylcholine receptors and electrophysiology in five cases. Muscle Nerve 4, 306-318CrossRefGoogle ScholarPubMed
2Engel, A. (1994) Myasthenic Syndromes, MacGraw-Hill, New YorkCrossRefGoogle Scholar
3Engel, A.G. (1980) Morphologic and immunopathologic findings in myasthenia gravis and in congenital myasthenic syndromes. J Neurol Neurosurg Psychiatry 43, 577-589CrossRefGoogle ScholarPubMed
4Vincent, A. et al. (2004) Seronegative myasthenia gravis. Semin Neurol 24, 125-133Google Scholar
5Vincent, A. and Leite, M.I. (2005) Neuromuscular junction autoimmune disease: muscle specific kinase antibodies and treatments for myasthenia gravis. Curr Opin Neurol 18, 519-525CrossRefGoogle ScholarPubMed
6Beeson, D., Palace, J. and Vincent, A. (1997) Congenital myasthenic syndromes. Curr Opin Neurol 10, 402-407CrossRefGoogle ScholarPubMed
7Vincent, A. et al. (1997) Genes at the junction–candidates for congenital myasthenic syndromes. Trends Neurosci 20, 15-22CrossRefGoogle ScholarPubMed
8Ohno, K. et al. (1995) Congenital myasthenic syndrome caused by prolonged acetylcholine receptor channel openings due to a mutation in the M2 domain of the epsilon subunit. Proc Natl Acad Sci U S A 92, 758-762CrossRefGoogle ScholarPubMed
9Engel, A.G. et al. (1996) End-plate acetylcholine receptor deficiency due to nonsense mutations in the epsilon subunit. Ann Neurol 40, 810-817Google Scholar
10Engel, A.G. et al. (1996) New mutations in acetylcholine receptor subunit genes reveal heterogeneity in the slow-channel congenital myasthenic syndrome. Hum Mol Genet 5, 1217-1227Google Scholar
11Ohno, K. et al. (2001) Choline acetyltransferase mutations cause myasthenic syndrome associated with episodic apnea in humans. Proc Natl Acad Sci U S A 98, 2017–2022CrossRefGoogle ScholarPubMed
12Donger, C. et al. (1998) Mutation in the human acetylcholinesterase-associated collagen gene, COLQ, is responsible for congenital myasthenic syndrome with end-plate acetylcholinesterase deficiency (Type Ic). Am J Hum Genet 63, 967–75CrossRefGoogle ScholarPubMed
13Ohno, K. et al. (1998) Human endplate acetylcholinesterase deficiency caused by mutations in the collagen-like tail subunit (ColQ) of the asymmetric enzyme. Proc Natl Acad Sci U S A 95, 9654-9659CrossRefGoogle ScholarPubMed
14Ohno, K. et al. (2002) Rapsyn mutations in humans cause endplate acetylcholine-receptor deficiency and myasthenic syndrome. Am J Hum Genet 70, 875-885CrossRefGoogle ScholarPubMed
15Chevessier, F. et al. (2004) MUSK, a new target for mutations causing congenital myasthenic syndrome. Hum Mol Genet 13, 3229-3240CrossRefGoogle Scholar
16Tsujino, A. et al. (2003) Myasthenic syndrome caused by mutation of the SCN4A sodium channel. Proc Natl Acad Sci U S A 100, 7377-7382CrossRefGoogle ScholarPubMed
17Beeson, D. et al. (2006) Dok-7 mutations underlie a neuromuscular junction synaptopathy. Science 313, 1975-1978CrossRefGoogle ScholarPubMed
18Beeson, D. et al. (2005) 126th International Workshop: Congenital Myasthenic Syndromes, 24–26 September 2004, Naarden, The Netherlands. Neuromuscul Disord 15, 498-512CrossRefGoogle Scholar
19Sanes, J.R. and Lichtman, J.W. (2001) Induction, assembly, maturation and maintenance of a postsynaptic apparatus. Nat Rev Neurosci 2, 791-805Google Scholar
20DeChiara, T.M. et al. (1996) The receptor tyrosine kinase MuSK is required for neuromuscular junction formation in vivo. Cell 85, 501-512Google Scholar
21Glass, D.J. et al. (1996) Agrin acts via a MuSK receptor complex. Cell 85, 513-523CrossRefGoogle Scholar
22Hoch, W. (1999) Formation of the neuromuscular junction. Agrin and its unusual receptors. Eur J Biochem 265, 1-10CrossRefGoogle ScholarPubMed
23Colledge, M. and Froehner, S.C. (1998) Signals mediating ion channel clustering at the neuromuscular junction. Curr Opin Neurobiol 8, 357-863CrossRefGoogle ScholarPubMed
24Froehner, S.C. et al. (1990) The postsynaptic 43K protein clusters muscle nicotinic acetylcholine receptors in Xenopus oocytes. Neuron 5, 403-410Google Scholar
25Sine, S.M. and Engel, A.G. (2006) Recent advances in Cys-loop receptor structure and function. Nature 440, 448-455CrossRefGoogle ScholarPubMed
26Engel, A.G. and Sine, S.M. (2005) Current understanding of congenital myasthenic syndromes. Curr Opin Pharmacol 5, 308-321Google Scholar
27Engel, A.G., Ohno, K. and Sine, S.M. (2003) Sleuthing molecular targets for neurological diseases at the neuromuscular junction. Nat Rev Neurosci 4, 339-352Google Scholar
28Ohno, K. and Engel, A.G. (2004) Congenital myasthenic syndromes: gene mutations. Neuromuscul Disord 14, 117-122Google Scholar
29Ealing, J. et al. (2002) Mutations in congenital myasthenic syndromes reveal an epsilon subunit C-terminal cysteine, C470, crucial for maturation and surface expression of adult AChR. Hum Mol Genet 11, 3087-3096CrossRefGoogle ScholarPubMed
30Abicht, A. et al. (1999) A common mutation (epsilon1267delG) in congenital myasthenic patients of Gypsy ethnic origin. Neurology 53, 1564-1569CrossRefGoogle ScholarPubMed
31Morar, B. et al. (2004) Mutation history of the roma/gypsies. Am J Hum Genet 75, 596-609CrossRefGoogle ScholarPubMed
32Kalaydjieva, L. et al. (2005) 125th ENMC International Workshop: Neuromuscular disorders in the Roma (Gypsy) population, 23–25 April 2004, Naarden, The Netherlands. Neuromuscul Disord 15, 65-71CrossRefGoogle Scholar
33Tournev, I. et al. (2005) Clinical phenotype and genetic epidemiology of congenital myasthenic syndrome type IA. Bulgarian Pediatrics 3, 17-20Google Scholar
34Ohno, K. and Engel, A.G. (2005) Splicing abnormalities in congenital myasthenic syndromes. Acta Myol 24, 50-54Google Scholar
35Müller, J.S. et al. (2005) An intronic base alteration of the CHRNE gene leading to a congenital myasthenic syndrome. Neurology 65, 463-465CrossRefGoogle ScholarPubMed
36Richard, P. et al. (2007) A synonymous CHRNE mutation responsible for an aberrant splicing leading to congenital myasthenic syndrome. Neuromuscul Disord 17, 409-414Google Scholar
37Middleton, L. et al. (1999) Chromosome 17p-linked myasthenias stem from defects in the acetylcholine receptor epsilon-subunit gene. Neurology 53, 1076-1082CrossRefGoogle ScholarPubMed
38Abicht, A. et al. (2002) A newly identified chromosomal microdeletion and an N-box mutation of the AChR epsilon gene cause a congenital myasthenic syndrome. Brain 125, 1005-1013Google Scholar
39Nichols, P. et al. (1999) Mutation of the acetylcholine receptor epsilon-subunit promoter in congenital myasthenic syndrome. Ann Neurol 45, 439-443Google Scholar
40Hesselmans, L.F. et al. (1993) Development of innervation of skeletal muscle fibers in man: relation to acetylcholine receptors. Anat Rec 236, 553-562CrossRefGoogle ScholarPubMed
41Missias, A.C. et al. (1996) Maturation of the acetylcholine receptor in skeletal muscle: regulation of the AChR gamma-to-epsilon switch. Dev Biol 179, 223-238CrossRefGoogle ScholarPubMed
42Yumoto, N., Wakatsuki, S. and Sehara-Fujisawa, A. (2005) The acetylcholine receptor gamma-to-epsilon switch occurs in individual endplates. Biochem Biophys Res Commun 331, 1522-1527Google Scholar
43Mishina, M. et al. (1986) Molecular distinction between fetal and adult forms of muscle acetylcholine receptor. Nature 321, 406-411CrossRefGoogle ScholarPubMed
44Hoffmann, K. et al. (2006) Escobar syndrome is a prenatal myasthenia caused by disruption of the acetylcholine receptor fetal gamma subunit. Am J Hum Genet 79, 303-312CrossRefGoogle ScholarPubMed
45Morgan, N.V. et al. (2006) Mutations in the embryonal subunit of the acetylcholine receptor (CHRNG) cause lethal and Escobar variants of multiple pterygium syndrome. Am J Hum Genet 79, 390-395CrossRefGoogle ScholarPubMed
46Rajab, A. et al. (2005) Escobar variant with pursed mouth, creased tongue, ophthalmologic features, and scoliosis in 6 children from Oman. Am J Med Genet A 134, 151-157Google Scholar
47Escobar, V. et al. (1978) Multiple pterygium syndrome. Am J Dis Child 132, 609-611Google Scholar
48Abicht, A. et al. (1997) Congenital myasthenic syndromes: clinical and genetic analysis of 18 patients. Eur J Med Res 2, 515–222Google Scholar
49Müller, J.S. et al. (2006) Novel mutations in the CHRNB1 gene in three patients affected by a congenital myasthenic syndrome. Neuromuscul Disord 16, 661 (Abstract)Google Scholar
50Vincent, A. et al. (2003) Antibodies in myasthenia gravis and related disorders. Ann N Y Acad Sci 998, 324-335CrossRefGoogle ScholarPubMed
51Müller, J.S. et al. (2003) Rapsyn N88K is a frequent cause of congenital myasthenic syndromes in European patients. Neurology 60, 1805-1810Google Scholar
52Burke, G. et al. (2003) Rapsyn mutations in hereditary myasthenia: distinct early- and late-onset phenotypes. Neurology 61, 826-828Google Scholar
53Dunne, V. and Maselli, R.A. (2003) Identification of pathogenic mutations in the human rapsyn gene. J Hum Genet 48, 204-207Google Scholar
54Richard, P. et al. (2003) Possible founder effect of rapsyn N88K mutation and identification of novel rapsyn mutations in congenital myasthenic syndromes. J Med Genet 40, e81Google Scholar
55Banwell, B.L. et al. (2004) Novel truncating RAPSN mutations causing congenital myasthenic syndrome responsive to 3,4-diaminopyridine. Neuromuscul Disord 14, 202-207CrossRefGoogle ScholarPubMed
56Ioos, C. et al. (2004) Congenital myasthenic syndrome due to rapsyn deficiency: three cases with arthrogryposis and bulbar symptoms. Neuropediatrics 35, 246-249Google Scholar
57Skeie, G.O. et al. (2006) Unusual features in a boy with the rapsyn N88K mutation. Neurology 67, 2262-2263CrossRefGoogle Scholar
58Ohno, K. and Engel, A.G. (2004) Lack of founder haplotype for the rapsyn N88K mutation: N88K is an ancient founder mutation or arises from multiple founders. J Med Genet 41, e8Google Scholar
59Müller, J.S. et al. (2004) The congenital myasthenic syndrome mutation RAPSN N88K derives from an ancient Indo-European founder. J Med Genet 41, e104CrossRefGoogle ScholarPubMed
60Müller, J.S. et al. (2006) Impaired receptor clustering in congenital myasthenic syndrome with novel RAPSN mutations. Neurology 67, 1159-1164CrossRefGoogle ScholarPubMed
61Ohno, K. et al. (2003) E-box mutations in the RAPSN promoter region in eight cases with congenital myasthenic syndrome. Hum Mol Genet 12, 739-748Google Scholar
62Dunne, V. and Maselli, R.A. (2004) Common founder effect of rapsyn N88K studied using intragenic markers. J Hum Genet 49, 366-369Google Scholar
63Gautam, M. et al. (1995) Failure of postsynaptic specialization to develop at neuromuscular junctions of rapsyn-deficient mice. Nature 377, 232-236Google Scholar
64Fuhrer, C. et al. (1999) Roles of rapsyn and agrin in interaction of postsynaptic proteins with acetylcholine receptors. J Neurosci 19, 6405-6416Google Scholar
65Ferns, M. and Carbonetto, S. (2001) Challenging the neurocentric view of neuromuscular synapse formation. Neuron 30, 311-314Google Scholar
66Ramarao, M.K. and Cohen, J.B. (1998) Mechanism of nicotinic acetylcholine receptor cluster formation by rapsyn. Proc Natl Acad Sci U S A 95, 4007-4012CrossRefGoogle ScholarPubMed
67Ramarao, M.K. et al. (2001) Role of rapsyn tetratricopeptide repeat and coiled-coil domains in self-association and nicotinic acetylcholine receptor clustering. J Biol Chem 276, 7475-7483Google Scholar
68Cartaud, A. et al. (1998) Evidence for in situ and in vitro association between beta-dystroglycan and the subsynaptic 43K rapsyn protein. Consequence for acetylcholine receptor clustering at the synapse. J Biol Chem 273, 11321-11326CrossRefGoogle ScholarPubMed
69Bartoli, M., Ramarao, M.K. and Cohen, J.B. (2001) Interactions of the rapsyn RING-H2 domain with dystroglycan. J Biol Chem 276, 24911-24917Google Scholar
70Maselli, R.A. et al. (2003) Rapsyn mutations in myasthenic syndrome due to impaired receptor clustering. Muscle Nerve 28, 293-301CrossRefGoogle ScholarPubMed
71Yasaki, E. et al. (2004) Electrophysiological and morphological characterization of a case of autosomal recessive congenital myasthenic syndrome with acetylcholine receptor deficiency due to a N88K rapsyn homozygous mutation. Neuromuscul Disord 14, 24-32CrossRefGoogle ScholarPubMed
72Cossins, J. et al. (2006) Diverse molecular mechanisms involved in AChR deficiency due to rapsyn mutations. Brain 129, 2773-2783Google Scholar
73Eckler, S.A., Kuehn, R. and Gautam, M. (2005) Deletion of N-terminal rapsyn domains disrupts clustering and has dominant negative effects on clustering of full-length rapsyn. Neuroscience 131, 661-670CrossRefGoogle ScholarPubMed
74Gautam, M. et al. (1996) Defective neuromuscular synaptogenesis in agrin-deficient mutant mice. Cell 85, 525-535Google Scholar
75Okada, K. et al. (2006) The muscle protein Dok-7 is essential for neuromuscular synaptogenesis. Science 312, 1802-1805Google Scholar
76Müller, J.S. et al. (2007) Phenotypical spectrum of DOK7 mutations in congenital myasthenic syndromes. Brain 130, 1497-1506Google Scholar
77Slater, C.R. et al. (2006) Pre- and post-synaptic abnormalities associated with impaired neuromuscular transmission in a group of patients with ‘limb-girdle myasthenia’. Brain 129, 2061-2076Google Scholar
78Palace, J. et al. (2007) Clinical features of the DOK7 neuromuscular junction synaptopathy. Brain 130, 1507-1515CrossRefGoogle ScholarPubMed
79Massoulie, J. et al. (1993) Structure and functions of acetylcholinesterase and butyrylcholinesterase. Prog Brain Res 98, 139-146Google Scholar
80Bon, S., Coussen, F. and Massoulie, J. (1997) Quaternary associations of acetylcholinesterase. II. The polyproline attachment domain of the collagen tail. J Biol Chem 272, 3016-3021CrossRefGoogle ScholarPubMed
81Simon, S., Krejci, E. and Massoulie, J. (1998) A four-to-one association between peptide motifs: four C-terminal domains from cholinesterase assemble with one proline-rich attachment domain (PRAD) in the secretory pathway. Embo J 17, 6178-6187Google Scholar
82Deprez, P.N. and Inestrosa, N.C. (1995) Two heparin-binding domains are present on the collagenic tail of asymmetric acetylcholinesterase. J Biol Chem 270, 11043-11046Google Scholar
83Ohno, K. et al. (2000) The spectrum of mutations causing end-plate acetylcholinesterase deficiency. Ann Neurol 47, 1621–703.0.CO;2-Q>CrossRefGoogle ScholarPubMed
84Shapira, Y.A. et al. (2002) Three novel COLQ mutations and variation of phenotypic expressivity due to G240X. Neurology 58, 603-609Google Scholar
85Ohno, K. et al. (1999) Congenital end-plate acetylcholinesterase deficiency caused by a nonsense mutation and an A– > G splice-donor-site mutation at position +3 of the collagenlike-tail-subunit gene (COLQ): how does G at position +3 result in aberrant splicing? Am J Hum Genet 65, 635-644CrossRefGoogle Scholar
86Müller, J.S. et al. (2004) Synaptic congenital myasthenic syndrome in three patients due to a novel missense mutation (T441A) of the COLQ gene. Neuropediatrics 35, 183-189Google Scholar
87Schmidt, C. et al. (2003) Congenital myasthenic syndrome due to a novel missense mutation in the gene encoding choline acetyltransferase. Neuromuscul Disord 13, 245-251Google Scholar
88Barisic, N. et al. (2005) Clinical variability of CMS-EA (congenital myasthenic syndrome with episodic apnea) due to identical CHAT mutations in two infants. Eur J Paediatr Neurol 9, 7-12Google Scholar
89Milone, M. et al. (2006) Novel congenital myasthenic syndromes associated with defects in quantal release. Neurology 66, 1223-1229Google Scholar
90Maselli, R.A. et al. (2001) Presynaptic congenital myasthenic syndrome due to quantal release deficiency. Neurology 57, 279-289CrossRefGoogle ScholarPubMed
91Bady, B., Chauplannaz, G. and Carrier, H. (1987) Congenital Lambert-Eaton myasthenic syndrome. J Neurol Neurosurg Psychiatry 50, 476-478Google Scholar
92Walls, T.J. et al. (1993) Congenital myasthenic syndrome associated with paucity of synaptic vesicles and reduced quantal release. Ann N Y Acad Sci 681, 461-468Google Scholar
93Engel, A.G., Ohno, K. and Sine, S.M. (2003) Congenital myasthenic syndromes, progress over the past decade. Muscle Nerve 27, 4-25Google Scholar
94Bestue-Cardiel, M. et al. (2005) Congenital endplate acetylcholinesterase deficiency responsive to ephedrine. Neurology 65, 144-146Google Scholar
95Colomer, J. et al. (2006) Long-term improvement of slow-channel congenital myasthenic syndrome with fluoxetine. Neuromuscul Disord 16, 329-333Google Scholar
96Harper, C.M., Fukodome, T. and Engel, A.G. (2003) Treatment of slow-channel congenital myasthenic syndrome with fluoxetine. Neurology 60, 1710-1713Google Scholar
97Harper, C.M. and Engel, A.G. (1998) Safety and efficacy of quinidine sulfate in slow-channel congenital myasthenic syndrome. Ann N Y Acad Sci 841, 203–106Google Scholar
98Shen, X.M. et al. (2006) Slow-channel mutation in acetylcholine receptor alphaM4 domain and its efficient knockdown. Ann Neurol 60, 128-136CrossRefGoogle ScholarPubMed
99Abdelgany, A., Wood, M. and Beeson, D. (2003) Allele-specific silencing of a pathogenic mutant acetylcholine receptor subunit by RNA interference. Hum Mol Genet 12, 2637-2644Google Scholar
100Missias, A.C. et al. (1997) Deficient development and maintenance of postsynaptic specializations in mutant mice lacking an ‘adult’ acetylcholine receptor subunit. Development 124, 5075-5086Google Scholar
101Witzemann, V. et al. (1996) Acetylcholine receptor epsilon-subunit deletion causes muscle weakness and atrophy in juvenile and adult mice. Proc Natl Acad Sci U S A 93, 13286-13291Google Scholar
102MacLennan, C. et al. (1997) Acetylcholine receptor expression in human extraocular muscles and their susceptibility to myasthenia gravis. Ann Neurol 41, 423-431Google Scholar
103Ohno, K. et al. (1997) Congenital myasthenic syndromes due to heteroallelic nonsense/missense mutations in the acetylcholine receptor epsilon subunit gene, identification and functional characterization of six new mutations. Hum Mol Genet 6, 753-766Google Scholar
104Cossins, J. et al. (2004) A mouse model of AChR deficiency syndrome with a phenotype reflecting the human condition. Hum Mol Genet 13, 2947-2957Google Scholar
105Feng, G. et al. (1999) Genetic analysis of collagen Q: roles in acetylcholinesterase and butyrylcholinesterase assembly and in synaptic structure and function. J Cell Biol 144, 1349-1360Google Scholar
106Leonard, J.P. and Salpeter, M.M. (1982) Calcium-mediated myopathy at neuromuscular junctions of normal and dystrophic muscle. Exp Neurol 76, 121-138Google Scholar
107Gomez, C.M. et al. (2002) Active calcium accumulation underlies severe weakness in a panel of mice with slow-channel syndrome. J Neurosci 22, 6447-6457Google Scholar
108Brandon, E.P. et al. (2003) Aberrant patterning of neuromuscular synapses in choline acetyltransferase-deficient mice. J Neurosci 23, 539-549Google Scholar

Further reading, resources and contacts

The congenital myasthenic syndromes entry on GeneReviews can be found at:

Engel, A.G. and Sine, S.M. (2005) Current understanding of congenital myasthenic syndromes. Curr Opin Pharmacol 5, 308-321Google Scholar
Hughes, B.W., Kusner, L.L. and Kaminski, H.J. (2006) Molecular architecture of the neuromuscular junction. Muscle Nerve 33, 445-461CrossRefGoogle ScholarPubMed
Engel, A.G. and Sine, S.M. (2005) Current understanding of congenital myasthenic syndromes. Curr Opin Pharmacol 5, 308-321Google Scholar
Hughes, B.W., Kusner, L.L. and Kaminski, H.J. (2006) Molecular architecture of the neuromuscular junction. Muscle Nerve 33, 445-461CrossRefGoogle ScholarPubMed