Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C1762617 (weakness)
 37,932 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Hypokalemic periodic paralysis (hypoKPP) is an autosomal dominant skeletal muscle disorder manifested by episodic weakness associated with low serum potassium. Genetic linkage analysis has localized the hypoKPP gene to chromosome 1q31-q32 near a dihydropyridine (DHP) receptor gene. This receptor functions as a voltage-gated calcium channel and is also critical for excitation-contraction coupling in a voltage-sensitive and calcium-independent manner. We have characterized patient-specific DHP receptor mutations in 11 probands of 33 independent hypoKPP kindreds that occur at one of two adjacent nucleotides within the same codon and predict substitution of a highly conserved arginine in the S4 segment of domain 4 with either histidine or glycine. In one kindred, the mutation arose de novo. Taken together, these data establish this DHP receptor as the hypoKPP gene. We are unaware of any other human diseases presently known to result from DHP receptor mutations.
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PMID:Dihydropyridine receptor mutations cause hypokalemic periodic paralysis. 800 73

We report a patient with small cell lung cancer associated with Lambert-Eaton myasthenic syndrome (LEMS) and subacute cerebellar degeneration (SCD). The patient was a 71-year-old man suffering from weakness of the limbs and a gait disturbance who developed limb ataxia and dysarthria one month after admission. Electrophysiologic studies confirmed the diagnosis of Lambert-Eaton myasthenic syndrome. Chest X-rays 2 months after admission revealed an abnormal shadow, and small cell lung cancer was diagnosed on the basis of biopsy specimens. Anti-voltage-gated calcium channel antibody was positive. Anti-Yo and -Hu antibodies were negative. The patient was treated by plasmapheresis and chemotherapy, which resulted in a transient improvement in the LEMS symptoms but not in the SCD. Fifteen cases of LEMS associated with SCD have been reported in the Japanese literature, and all were accompanied by small cell lung cancer. We discuss the frequency of association with LEMS and SCD and the effects of plasmapheresis and chemotherapy in both diseases.
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PMID:[Report of a case of small cell lung cancer associated with Lambert-Eaton myasthenic syndrome and subacute cerebellar degeneration--with a review of the Japanese literature]. 819 44

Calcium homeostasis and ultrastructure are altered in motor axon terminals (AT) of amyotrophic lateral sclerosis (ALS) patients and in mice injected with ALS IgG and exhibit increased density of synaptic vesicles and increased intracellular calcium. To develop an immune-mediated passive transfer experimental model of both systemic weakness and altered morphology, mice were inoculated intraperitoneally with anti-motoneuronal IgG. Animals initially manifested muscle stiffness and evidence of autonomic cholinergic hyperactivity. Electron microscopic cytochemistry within 12 hours (h) demonstrated significantly increased density of synaptic vesicles and calcium both in axon terminals of neuromuscular junctions and synaptic boutons on spinal motoneurons. After 24 h the mice were severely weak and premorbid. The number of synaptic vesicles was still larger than normal, but calcium was depleted from axon terminals and synaptic boutons. The motoneuron perikarya demonstrated the dilatation of the Golgi system and the rough endoplasmic reticulum with an increased amount of calcium. The NMDA receptor antagonist, MK-801, and the L-type calcium channel antagonist, Diltiazem, prevented clinical symptoms and some morphological alterations. These data demonstrate that high titer anti-motoneuronal IgG can induce severe weakness and produce similar ultrastructural features of motor axon terminals in human ALS and in mice injected with ALS IgG, and support a key role for calcium in selective vulnerability of motoneurons.
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PMID:Altered calcium homeostasis and ultrastructure in motoneurons of mice caused by passively transferred anti-motoneuronal IgG. 899 Jan 26

Hypokalemic periodic paralysis (hypoPP) is an autosomal dominant disorder characterized by acute attacks of muscle weakness concomitant to a drop in blood potassium levels. Recent molecular work has shown that hypoPP is due to mutations in a skeletal muscle voltage-gated calcium channel: the dihydropyridine receptor (DHP receptor). Mutations affect segments S4 of domains II and IV, changing an arginine in position 528 and 1239 into an histidine, or an histidine or a glycine respectively. Surprisingly, expressing in vitro mutants channels in a non-muscular environment resulted in functional calcium channels with minor modifications in electrophysiological properties. Expressing mutant channels in a muscular environment or transgenic mice might help to bridge the gap between the knowledge of the molecular defect and the understanding of the pathophysiology of the disease.
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PMID:Hypokalemic periodic paralysis: an autosomal dominant muscle disorder caused by mutations in a voltage-gated calcium channel. 919 5

Some of the most common diseases in humans occur intermittently in people who are otherwise healthy and active. Such disorders include migraine headache, epilepsy, and cardiac arrhythmias. Because electrical signals are critical to the function of neurons, muscle cells, and heart cells, proteins that regulate electrical signaling in these cells are logical sites where abnormalities might lead to disease. All of these diseases have prominent genetic components. Difficulty in understanding these diseases arises from the complexity of the clinical phenotypes as well as from the genetic heterogeneity that is almost certain to exist. Therefore, early work in may laboratory was aimed at understanding the pathogenesis of rare disorders that are similar in their episodic nature. These disorders of muscle (the periodic paralyses), lead to attacks of weakness that occur intermittently in otherwise normal people. We, and others, have shown that hyperkalemic periodic paralysis (hyperKPP) and paramyotonia congenita (PC) result from mutations in a gene encoding a skeletal muscle sodium channel. We have also shown that hypokalemic periodic paralysis (hypoKPP) is caused by mutations in a gene encoding a voltage-gated calcium channel. The characterization of these diseases as channelopathies has served as a paradigm for other episodic disorders. One example is periodic ataxia, which results from mutations in voltage-gated potassium calcium channels. Long QT syndrome, an episodic cardiac dysrhythmia syndrome, is known to result from mutations in either voltage-gated sodium or potassium channels. We have recently mapped genes that cause a familial paroxysmal dyskinesia (non-kinesiogenic paroxysmal dystonia/choreoathetosis) in humans and a reflex epilepsy in mice. The similarities among all these disorders, including their episodic nature, precipitating factors, and therapeutic responses, are striking. Understanding gained from work in these rare monogenic episodic disorders is not only allowing characterization of the molecular and physiologic basis of these diseases, but may ultimately shed light on our understanding of the pathophysiology of more common and genetically complex disorders of the central nervous system.
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PMID:Channelopathies: ion channel disorders of muscle as a paradigm for paroxysmal disorders of the nervous system. 919 7

Since 1990, many mutations, in genes encoding ion channels have been discovered to cause disorders characterized by hyper- or hypoexcitability of skeletal muscle or the central nervous system (CNS): i) mutations in the muscle chloride channel gene lead to a loss or change of function of the channels and cause an abnormally low total chloride conductance resulting in hyperexcitability of the muscle fiber membrane in the dominant and recessive form of myotonia congenita; ii) numerous dominant point mutations in the gene encoding the muscle sodium channel alpha-subunit cause incomplete sodium channel inactivation. Dependent on the inactivation parameter altered and the degree of the gain of function induced by a given mutation, the muscle episodically becomes hyper- or hypoexcitable (i.e. stiff or weak), particularly in response to elevated serum potassium (potassium-aggravated myotonia, hyperkalemic periodic paralysis) or cold environment (paramyotonia congenita); iii) dominant point mutations in the gene coding for the muscle L-type calcium channel alpha(1)-subunit can cause episodes of muscle inexcitability (i.e. weakness), particularly in response to lowered serum potassium (hypokalemic periodic paralysis); despite the recently discovered etiology of the disease, the pathogenesis of the weakness is still unknown; iv) dominant mutations in a voltage-gated potassium channel expressed in the CNS cause episodic ataxia type 1 presumably by antagonizing repolarization of the cell membrane; v) dominant mutations in a neuronal calcium channel alpha-subunit may cause either episodic ataxia type II or familial hemiplegic migraine by a so far unknown pathomechanism; vi) the first mutation in an ion channel associated with an inherited form of epilepsy, nocturnal frontal lobe epilepsy, was found in the alpha(4)-subunit of a neuronal nicotinic acetylcholine receptor.
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PMID:[Ion channel diseases in neurology]. 948 Feb 90

The Lambert-Eaton myasthenic syndrome (LEMS) is an autoimmune disease that is often associated with lung cancer which shares a common antigenic protein with the motor nerve terminal. The myasthenic weakness is caused by an antibody-induced reduction in the release of acetylcholine from the nerve terminal. This study was undertaken to determine the target of LEMS antibodies and specify the voltage-gated calcium channel (VGCC) through which calcium influxes following the presynaptic membrane depolarization. Among the 5 types of VGCC, we found that the P/Q-type was highly recognized by LEMS antibodies. Using synthetic peptides or recombinant proteins as antigens for testing LEMS patients' sera or inducing an animal model of LEMS, we specified the S5-S6 linker regions in 3 of 4 domains constituting the alpha1 subunit of P/Q-type VGCC as immunodominant sites. Synaptotagmin, one of the functionally VGCC-associated proteins and a protein functioning as a calcium sensor for exocytosis of synaptic vesicles, was also found to be a pathogenic immunogen of LEMS when the recombinant protein for antibody assay and the synthetic peptide for the induction of animal model were used as antigens. The present study forms a united front against cancer and cancer-related myasthenic syndrome.
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PMID:An autoimmune channelopathy associated with cancer: Lambert-Eaton myasthenic syndrome. 1022 62

A 60-year-old man with a 40-year history of seronegative ocular myasthenia gravis (MG) developed generalized weakness cumulating crisis over 2 years. On admission, ophthalmoplegia, severe ptosis and marked generalized weakness were observed without autonomic symptoms and signs. The deep tendon reflexes were decreased, but were normalized after repeated muscle contractions. EMG of the abductor digiti minimi muscle showed low amplitude in compound muscle action potentials (0.6 mV), waxing phenomenon (292%) with 20 Hz repetitive nerve stimulation (RNS), waning phenomenon (34%) in 3 Hz RNS, and posttetanic facilitation (393%). Stimulated single fiber EMG showed reduced jitter with higher stimulation rates. Serum anti-P/Q-type voltage-gated calcium channel antibodies were negative with no evidence of malignancy. Sensitive assay of acetylcholine receptor antibody in serum revealed a positive titer, while conventional assay was negative. A muscle biopsy was performed and immune complex deposition was demonstrated at the endplate. A nearly complete clinical remission and normalization of electrophysiological features followed immunoadsorption and prednisolone therapy. A sensitive immunoassay of acetylcholine receptor antibodies and immunolocalization of complement at the endplate are useful diagnostic tools in cases presenting with features of myasthenia gravis and Lambert-Eaton myasthenic syndrome.
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PMID:[Myasthenia gravis with electrophysiological features of Lambert-Eaton myasthenic syndrome: usefulness of serum autoantibodies assay and neuromuscular junction biopsy]. 1042 44

The Lambert-Eaton myasthenic syndrome (LEMS) is a disorder of neuromuscular transmission characterized by the reduced quantal release of acetylcholine from the motor nerve terminal, wherein the P/Q-type of voltage-gated calcium channel (VGCC) and is attacked by a majority of LEMS antibodies. Using the molecular structure of the alpha1 subunit (consisting of 4 domains) of the P/Q-type VGCC as a reference, we synthesized the extracellular region (S5-S6 linker) of the domain III, known as the segment which plays an important role in channel functions. Six of the ten Lewis rats immunized with this synthetic peptide conjugated with carrier protein showed moderate weakness (grade 1 in a 3-graded scale, for myasthenic weakness in experimental animals) and a reduction in acetylcholine quantum content of end-plate potentials. Antipeptide antibodies raised in test rats reacted with omega-conotoxin MVIIC-sensitive cerebellar extract (P/Q-type VGCC) and the domain III peptide inhibited the binding of rat antibodies to VGCCs. Our findings suggest the identification of one of the potential epitopes of LEMS antibodies.
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PMID:Calcium channel peptide can cause an autoimmune-mediated model of Lambert-Eaton myasthenic syndrome in rats. 1047 6

This study was undertaken to analyse the clinical and immunological features in a large group of Lambert-Eaton Myasthenic Syndrome (LEMS) patients (n = 110). In the Japanese LEMS patients studied, there was a male predominance with a male to female ratio of 3:1. The age at onset of neurological symptoms ranged between 17 and 80 years with a mean of 62 years. Malignancy was detected in 69% of the patients, of whom 61% had small cell lung carcinoma (SCLC). Neurological symptoms preceded a diagnosis of malignancy in 84% of cases. The neurological findings were similar in all patients and consisted of lower limb weakness in 97%, upper limb weakness in 80%, hyporeflexia in 85%, autonomic dysfunction in 37% (dry mouth in 31%, constipation in 11%, impaired sweating, urinary disturbance, impotence, and blurred vision in less than 10%), blepharoptosis in 28% and ophthalmoplegia in 5%. Signs of cerebellar involvement are noted in 9% and all of these patients had SCLC. Of 110 patients with LEMS, 85% had detectable antibodies against P/Q-type voltage-gated calcium channel (P/Q-type VGCC). Seronegative patients (15%) had similar neurological findings, but a lower incidence of SCLC than seropositive patients. The clinical features of our patients were very similar to those observed in British LEMS patients (n = 50), but autonomic features in our study were less prevalent than reported in British patients.
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PMID:[The Lambert-Eaton myasthenic syndrome: a study of 110 Japanese cases]. 1079 Oct 87


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