Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.1.7 (acetylcholinesterase)
 28,390 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Congenital myasthenic syndromes (CMSs) are a group of inherited disorders of neuromuscular transmission characterized by fatigable muscle weakness. One major subgroup of patients shows a characteristic "limb girdle" pattern of muscle weakness, in which the muscles have small, simplified neuromuscular junctions but normal acetylcholine receptor and acetylcholinesterase function. We showed that recessive inheritance of mutations in Dok-7, which result in a defective structure of the neuromuscular junction, is a cause of CMS with proximal muscle weakness.
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PMID:Dok-7 mutations underlie a neuromuscular junction synaptopathy. 1691 26

Mutations in DOK7 have recently been shown to underlie a recessive congenital myasthenic syndrome (CMS) associated with small simplified neuromuscular junctions ('synaptopathy') but normal acetylcholine receptor and acetylcholinesterase function. We identified DOK7 mutations in 27 patients from 24 kinships. Mutation 1124_1127dupTGCC was common, present in 20 out of 24 kinships. All patients were found to have at least one allele with a frameshift mutation in DOK7 exon 7, suggesting that loss of function(s) associated with the C-terminal region of Dok-7 underlies this disorder. In 15 patients, we were able to study the clinical features in detail. Clinical onset was usually characterized by difficulty in walking developing after normal motor milestones. Proximal muscles were usually more affected than distal, leading to a 'limb-girdle' pattern of weakness; although ptosis was often present from an early age, eye movements were rarely involved. Patients did not show long-term benefit from anticholinesterase medication and sometimes worsened, and where tried responded to ephedrine. The phenotype can be distinguished from 'limb-girdle' myasthenia associated with tubular aggregates, where DOK7 mutations were not detected and patients respond to anticholinesterase treatments. CMS due to DOK7 mutations are common within our UK cohort and is likely to be under-diagnosed; recognition of the phenotype will help clinical diagnosis, targeted genetic screening and appropriate management.
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PMID:Clinical features of the DOK7 neuromuscular junction synaptopathy. 1745 75

During the past five years many patients suffering from congenital myasthenic syndromes (CMS) have been identified worldwide and novel causative genes and mutations have been discovered. The disease genes now include those encoding each subunit of the acetylcholine receptor (AChR), the ColQ part of acetylcholinesterase (AChE), choline acetyltransferase, Na(v)1.4, MuSK, and Dok-7. Moreover, emerging genotype-phenotype correlations are providing clues for targeted mutation analysis. This review focuses on the recent observations in selected CMS.
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PMID:Further observations in congenital myasthenic syndromes. 1856 59

Congenital myasthenic syndromes are rare genetic disorders compromising neuromuscular transmission. The defects are mainly mutations in the muscle acetylcholine receptor, or associated proteins rapsyn and Dok-7. We analyzed three unrelated Italian patients with typical clinical features of congenital myasthenic syndrome, who all benefitted from cholinesterase inhibitors. We found five mutations: a previously unreported homozygous alphaG378D mutation in the CHRNA1 gene, a previously unreported heterozygous epsilonY8X mutation associated with a known heterozygous epsilonM292del deletion in the CHRNE gene, and the common heterozygous N88K mutation associated with a previously unreported heterozygous IVS1 + 2T > G splice site mutation in the RAPSN gene. All three patients had two mutant alleles; parents or offspring with a single mutated allele were asymptomatic, thus all mutations exerted their effects recessively. The previously unreported mutations are likely to reduce the number of AChRs at the motor endplate, although the alphaG378D mutation might produce a mild fast channel syndrome. The alphaG378D mutation was recessive, but recessive CHRNA1 mutations have rarely been reported previously, so studies on the effect of this mutation at the cellular level would be of interest.
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PMID:Identification of previously unreported mutations in CHRNA1, CHRNE and RAPSN genes in three unrelated Italian patients with congenital myasthenic syndromes. 2015 24

Genetic defects in molecules expressed at the neuromuscular junction (NMJ) cause congenital myasthenic syndromes (CMSs), which are characterized by muscle weakness, abnormal fatigability, amyotrophy, and minor facial anomalies. Muscle weakness mostly develops under 2 years but is also sometimes seen in adults. Mutations identified to date include (i) muscle nicotinic acetylcholine receptor (AChR) subunits, (ii) rapsyn that anchors and clusters AChRs at the neuromuscular junction, (iii) agrin that is released from the nerve terminal and induces AChR clustering by stimulating the downstream LRP4/MuSK/Dok-7/rapsyn/AChR pathway, (iv) muscle-specific kinase (MuSK) that transmits the AChR-clustering signal from agrin/LRP4 to rapsyn/AChR, (v) Dok-7 that transmits the AChR-clustering signal from agrin/LRP4/MuSK to rapsyn/AChR, (vi) skeletal muscle sodium channel type 1.4 (Nav1.4) that spreads the depolarization potential from the endplate throughout muscle fibers, (vii) collagen Q that anchors acetylcholinesterase to the synaptic basal lamina, and (viii) choline acetyltransferase that resynthesizes acetylcholine from recycled choline at the nerve terminal. In addition, mutations in the heparin sulfate proteoglycan perlecan, which binds to many molecules including collagen Q and dystroglycan, causes Schwartz-Jampel syndrome. Interestingly, mutations in LRP4 cause Cenani-Lenz syndactyly syndrome but not CMS. AChR, MuSK, and LRP4 are also targets of auto-antibodies in myasthenia gravis. In addition, molecules at the NMJ are targets of many other disease states AChRs are blocked by the snake toxin alpha-bungarotoxin and the plant poison curare. The presynaptic SNARE complex is attacked by botulinum toxin. Acetylcholinesterase is inhibited by the nerve gas sarin and by organophosphate pesticides. This review focuses on the molecular bases underlying defects of AChR, rapsyn, Nav1.4, collagen Q, and choline acetyltransferase.
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PMID:[Genetic defects and disorders at the neuromuscular junction]. 2174 36

Congenital myasthenic syndromes (CMS) are caused by germline mutations of molecules expressed at the neuromuscular junction (NMJ). Mutations in 11 molecules encoded by 15 genes have been reported in association with CMS. CMS can be classified into four clinical categories. First, missense mutations in the acetylcholine receptor (AChR) subunits lead to slow- and fast-channel syndromes. Second, mutations in the AChR subunits, rapsyn, agrin, MuSK, Dok-7, plectirn, and GFPT1 lead to endplate AChR deficiency. Third, collagen Q (ColQ) anchors acetylcholinesterase (AChE) to the synaptic basal lamina and mutations in COLQ lead to endplate AChE deficiency. By exploiting the synaptic basal lamina-targeting signal of ColQ, we recently reported that the exogenously administered AChE/ColQ complex can be specifically localized to the NMJ. The protein-anchoring therapy can be potentially applicable to a wide spectrum of defective extracellular matrix molecules. Fourth, CMS associated with episodic apnea is caused by mutations in choline acetyltransferase (ChAT) and skeletal muscle voltage-gated sodium channel (Na(V)1.4). In the past two years, we diagnosed 15 cases with CMS in Japan, and identified mutations in 12 patients. All the mutations except for one are unique to Japanese patients. We assume that more CMS cases still remain undiagnosed in Japan.
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PMID:[Congenital myasthenic syndromes]. 2319 49