Linked Life Data

8872460

Source:http://linkedlifedata.com/resource/pubmed/id/8872460

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
9
pubmed:dateCreated
1997-1-8
pubmed:abstractText
Mutations in genes encoding the epsilon, delta, beta and alpha subunits of the end plate acetylcholine (ACh) receptor (AChR) are described and functionally characterized in three slow-channel congenital myasthenic syndrome patients. All three had prolonged end plate currents and AChR channel opening episodes and an end plate myopathy with loss of AChR from degenerating junctional folds. Genetic analysis revealed heterozygous mutations: epsilon L269F and delta Q267E in Patient 1, beta V266M in Patient 2, and alpha N217K in Patient 3 that were not detected in 100 normal controls. Patients 1 and 2 have no similarly affected relatives; in Patient 3, the mutation cosegregates with the disease in three generations. epsilon L269F, delta Q267E and beta V266M occur in the second and alpha N217K in the first transmembrane domain of AChR subunits; all have been postulated to contribute to the lining of the upper half of the channel lumen and all but delta Q267E are positioned toward the channel lumen, and introduce an enlarged side chain. Expression studies in HEK cells indicate that all of the mutations express normal amounts of AChR. epsilon L269F, beta V266M, and alpha N217K slow the rate of channel closure in the presence of ACh and increase apparent affinity for ACh; epsilon L269F and alpha N217K enhance desensitization, and epsilon L269F and beta V266M cause pathologic channel openings in the absence of ACh, rendering the channel leaky, delta Q267E has none of these effects and is therefore a rare polymorphism or a benign mutation. The end plate myopathy stems from cationic overloading of the postsynaptic region. The safety margin of neuromuscular transmission is compromised by AChR loss from the junctional folds and by a depolarization block owing to temporal summation of prolonged end plate potentials at physiologic rates of stimulation.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0964-6906
pubmed:author
pubmed:issnType
Print
pubmed:volume
5
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1217-27
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1996
pubmed:articleTitle
New mutations in acetylcholine receptor subunit genes reveal heterogeneity in the slow-channel congenital myasthenic syndrome.
pubmed:affiliation
Department of Neurology, Mayo Clinic and Foundation, Rochester, MN 55905, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Case Reports, Research Support, Non-U.S. Gov't