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Query: UMLS:C0024591 (malignant hyperthermia)
 2,353 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Malignant hyperthermia (MH) is a potentially lethal pharmacogenetic disease with autosomal dominant inheritance triggered by exposure to commonly used inhalational anaesthetics or depolarising muscle relaxants. A MHS locus has been identified on human chromosome 19q12-q13.2 and the gene for the skeletal muscle calcium release channel of sarcoplasmic reticulum (ryanodine receptor) (RYR1) is considered a candidate for the molecular defect. However, MH has been shown to be genetically heterogeneous, and in the ensuing search for other MHS genes, a locus on chromosome 17q has been proposed, and the gene for the adult muscle sodium channel (SCN4A) was suggested as a candidate. We performed linkage studies using polymorphic microsatellite markers for subunits of the skeletal muscle dihydropyridine (DHP) receptor, CACNL1A3 mapped to chromosome 1q, as well as C-ACNLB1 and CACNLG, the latter two localised on chromosome 17q11.2-q24 in proximity to the proposed MHS2 and the SCN4A loci, and we also included markers for the loci D17S250, D17S579, NM23 (NME1), GH1, and SCN4A from that region. Our results exclude the alpha 1, beta 1 and gamma subunit of the DHP receptor as well as the SCN4A locus from that region. Our results exclude the alpha 1, beta 1, and gamma subunit of the DHP receptor as well as the SCN4A locus as candidates for the molecular defect in MHS for these pedigrees where also the RYR1 on chromosome 19q13.1 has been excluded. A multipoint analysis excludes the disease from the entire 84 cM interval containing the proposed MHS locus on chromosome 17q.(ABSTRACT TRUNCATED AT 250 WORDS)
Hum Mol Genet 1993 Jul
PMID:Exclusion of malignant hyperthermia susceptibility (MHS) from a putative MHS2 locus on chromosome 17q and of the alpha 1, beta 1, and gamma subunits of the dihydropyridine receptor calcium channel as candidates for the molecular defect. 839 39

Malignant hyperthermia susceptibility (MHS) is an autosomal dominant disorder of skeletal muscle which manifests as a life-threatening hypermetabolic crisis triggered by commonly-used inhalation anaesthetics and depolarizing muscle relaxants. Defects in the ryanodine receptor (RYR1) protein have been proposed to underly MHS, but significant genetic heterogeneity in MHS has recently been demonstrated. In order to investigate the potential roles played by other skeletal muscle calcium channels in MHS, we isolated cosmids containing the gene encoding the beta 1-subunit of skeletal muscle L-type voltage-dependent calcium channel (CACNLB1). We identified a new, highly polymorphic dinucleotide repeat motif close to this gene, and linkage analysis placed the marker proximal to the HOX2B locus, previously localized to chromosome segment 17q21-q22. We recently identified a novel marker within the gamma-subunit locus (CACNLG) at band 17q24, and since both markers are within the 17q11.2-q24 region reported to contain the MHS2 locus, we tested them for linkage in MHS families whose disease trait has been shown not to co-segregate with markers for the RYR1 region on chromosome 19q13.1. Our results exclude CACNLB1 and CACNLG as candidate genes for MHS2, and do not support the reported chromosome 17q localization for the MHS2 locus in our families.
Hum Mol Genet 1993 Jul
PMID:Genetic mapping of the beta 1- and gamma-subunits of the human skeletal muscle L-type voltage-dependent calcium channel on chromosome 17q and exclusion as candidate genes for malignant hyperthermia susceptibility. 839 40

Several human Mendelian diseases, including the long-QT syndrome, malignant hyperthermia, and episodic ataxia/myokymia syndrome, have recently been demonstrated to be due to mutations in ion channel genes. Systematic mapping of ion channel genes may therefore reveal candidates for other heritable disorders. In this study, the GenBank and dbEST databases were used to identify members of several ion channel families (voltage-gated calcium and sodium, cardiac chloride, and all classes of potassium channels). Genes and ESTs without prior map localization were identified based on GDB and OWL database information and 15 genes and ESTs were selected for mapping. Of these 15, only the serotonin receptor 5HT3R had been previously mapped to a chromosome. A somatic cell hybrid panel (SCH) was screened with an STS from each gene and, if necessary the results verified by a second SCH panel. For three ESTs, rodent derived PCR products of the same size as the human STS precluded SCH mapping. For these three, human P1 clones were isolated and the genomic location was determined by metaphase FISH. These genes and ESTs can now be further evaluated as candidate genes for inherited cardiac, neuromuscular and psychiatric disorders mapped to these chromosomes. Furthermore, the ESTs developed in this study can be used to isolate genomic clones, enabling the determination of each transcript's genomic structure and physical map location. This approach may also be applicable to other gene families and may aid in the identification of candidate genes for groups of related heritable disorders.
Somat Cell Mol Genet 1996 Sep
PMID:Chromosomal localization of 15 ion channel genes. 903 51

A microassay is demonstrated for functional characterization of the Ca(2+)-release channel (CRC) of sarcoplasmic reticulum (SR) of skeletal muscle using swine with susceptibility to malignant hyperthermia (MH). Diluted muscle homogenates, indo-1 and ratiometric dual-emission spectrofluorometry are used to monitor Ca(2+)-lowering activity in real-time in the presence and absence of ryanodine at exposures that open and close the CRC. Reactions are initiated with 50 microM CaCl2 to raise ionized Ca2+ concentration near 1 microM and MgATP to activate the Ca(2+)-ATPase pump. Oxalate is included to precipitate Ca2+ within the SR. The assay requires less than 30 mg muscle, which may be cryopreserved, and is completed within 20 min of thawing the tissue. Maximum SR Ca(2+)-ATPase pumping and CRC activities, degree of CRC activation, and Ca(2+)-buffering capacity can be determined. Using this assay we studied muscle from MH-susceptible swine and demonstrated that whereas maximal Ca(2+)-ATPase pumping and CRC activities are normal, the CRC activity after addition of a bolus of Ca2+ is 50% greater in heterozygotes and 100% greater in homozygotes for the MH mutation. Hypersensitivity to CRC agonists, such as caffeine, and an associated hyposensitivity to CRC antagonists such as Mg2+ is also demonstrated. Genotypes for the MH mutation site can be discriminated from each other by determining Ca(2+)-lowering activities and the effect of ryanodine on them.
Mol Cell Biochem 1997 Feb
PMID:Rapid, simple and sensitive microassay for skeletal muscle homogenates in the functional assessment of the Ca-release channel of sarcoplasmic reticulum: application to diagnosis of susceptibility to malignant hyperthermia. 905 82

Malignant hyperthermia (MH) is an autosomal dominant disorder which is potentially lethal in susceptible individuals on exposure to commonly used inhalational anaesthetics and depolarising muscle relaxants. Crises reflect the consequences of disturbed skeletal muscle calcium homeostasis. Susceptibility was first localised to chromosome 19q13.1 and the skeletal muscle ryanodine receptor, RYR1 (the calcium release channel of the sarcoplasmic reticulum). Defects in this gene have been identified which cosegregate with the MHS phenotype and evidence as to their potential causal roles has accumulated. MH has, however, been shown to be genetically heterogeneous, additional loci on chromosomes 3q, 17q and 7q being proposed. Pedigrees remain in Europe where linkage status is still unclear. In a collaborative search of the human genome conducted with three pedigrees whose disease status was classified according to the European IVCT protocol we have evidence to suggest that at least two further loci exist for MH susceptibility. One of these locates to chromosome 1q, the site of a candidate gene, CACNL1A3, encoding the alpha-subunit of the dihydropyridine receptor. The second region resides on chromosome 5p to where no known candidate has been mapped to date. The third family exhibited inconclusive results which suggests the existence of at least one other locus. This study adds to the evidence for considerable genetic heterogeneity in MH and will provide a route to further our understanding of the molecular pathology of the condition.
Hum Mol Genet 1997 Jun
PMID:A genome wide search for susceptibility loci in three European malignant hyperthermia pedigrees. 917 45

The missing link in our understanding of excitation-contraction coupling (ECC) in skeletal muscle is the mechanism by which Ca2+ increases in the cytosol to trigger contraction. We discuss here a general background of intracellular Ca2+ handling, some characteristics of the major proteins involved in Ca2+ flow during ECC, and mechanisms currently believed to explain the increase in Ca2+ upon stimulation of muscle cells. These mechanisms include the calcium-induced calcium release, the direct coupled mechanism in which a plasma membrane and sarcoplasmic reticulum membrane protein interact, and mechanisms involving Ca2+ secretagogues that are known to elicit increases in calcium in other cells, inositol trisphosphate, and cyclic ADP ribose. We also consider possible roles for proteins associated with the principal calcium release channel of the sarcoplasmic reticulum, the ryanodine receptor. Finally, we discuss malignant hyperthermia, a disease associated directly with aberrant control of muscle cell calcium release.
Mol Genet Metab 1998 Oct
PMID:Control of calcium in skeletal muscle excitation-contraction coupling: implications for malignant hyperthermia. 978 3

Extremely large protein complexes involved in the Ca2+-regulatory system of the excitation-contraction-relaxation cycle have been identified in skeletal muscle, i.e. clusters of the Ca2+-binding protein calsequestrin, apparent tetramers of Ca2+-ATPase pump units and complexes between the transverse-tubular alpha1-dihydropyridine receptor and ryanodine receptor Ca2+-release channel tetramers of the sarcoplasmic reticulum. While receptor interactions appear to be crucial for signal transduction during excitation-contraction coupling, avoidance of passive disintegration of junctional complexes and stabilization of receptor interactions may be mediated by disulfide-bonded clusters of triadin. Oligomerization of Ca2+-release, Ca2+-sequestration and Ca2+-uptake complexes appear to be an intrinsic property of these muscle membrane proteins. During chronic low-frequency stimulation, the expression of triad receptors is decreased while conditioning has only a marginal effect on Ca2+-binding proteins. In contrast, muscle stimulation induces a switch from the fast-twitch Ca2+-ATPase to its slow-twitch/cardiac isoform. These alterations in Ca2+-handling might reflect early functional adaptations to electrical stimulation. Studying Ca2+-homeostasis in transformed muscles is important regarding the evaluation of new clinical applications such as dynamic cardiomyoplasty. Studies of Ca2+-handling in skeletal muscle fibers have not only increased our understanding of muscle regulation, but have given important insights into the molecular pathogenesis of malignant hyperthermia, hypokalemic periodic paralysis and Brody disease.
Int J Mol Med 1998 Apr
PMID:Excitation-contraction-relaxation cycle: role of Ca2+-regulatory membrane proteins in normal, stimulated and pathological skeletal muscle (review). 985 82

The skeletal muscle ryanodine receptor (RYR1) is a calcium release channel that mediates efflux of calcium ions from the sarcoplasmic reticulum into the myoplasm during excitation-contraction coupling. Mutations in the RYR1 gene have been detected in about 50% of the patients suffering from malignant hyperthermia (MH), but evidence is accumulating that other genetic defects can also lead to MH in humans. MH is a life-threatening disorder induced by exposure to volatile anesthetics and/or the muscle relaxans succinylcholin during surgical procedures in affected patients. MH leads to skeletal muscle rigidity, hypermetabolism and rapid rise in body temperature. MH is also known in pigs where it is triggered by stress and therefore often referred to as porcine stress syndrome. The existence of an animal model has greatly faciliated the elucidation of the basis for the human disease. This review describes recent advances in the understanding of the physiological action of ryanodine receptors and new insights regarding the relation between different RYR1 mutations and distinct phenotypical appearances.
Int J Mol Med 1998 Sep
PMID:Ryanodine receptors and their role in genetic diseases (review). 985 1

Meat quality of pigs is dependent on biochemical and biophysical processes in the time course post mortem (p.m.) and is associated with the intracellular Ca2+ homeostasis. However, there is little known about changes in the Ca2+ transporting proteins controlling the Ca2+ uptake of sarcoplasmic reticulum (SR) in the time course p.m. In this study changes in the Ca2+ transporting proteins were investigated in homogenates of longissimus muscles of 4 malignant hyperthermia susceptible (MHS) and 6 malignant hyperthermia resistant (MHR) Pietrain pigs. Muscle samples were obtained at different time intervals: biopsy 2 h prior slaughtering and from the carcass immediately after exsanguination (0 h), 45 min, 4 h, and 22 h p.m. The SR Ca2+ uptake rate was measured immediately after homogenization with closed calcium release channel (CRC), with opened CRC and without manipulation of CRC. Additionally the SR Ca2+ ATPase activity was determined. The results show: (i) The ability of SR to sequester Ca2+ declined to about 60% in the first 45 min p.m. in MHS samples irrespective of CRC state, whereas in MHR samples this decline was about 5%; (ii) Ca2+ uptake and Ca2+ ATPase activity were not different between the biopsy and 0 h samples, i.e. the stress of slaughter was of no immediate influence; (iii) The Ca2+ ATPase activity of the SR declined at about the same rate as the Ca2+ uptake in both MHS and MHR pig samples in the course of time p.m.; (iv) In samples, taken immediately after exsanguination, the Ca2+ ATPase activity of MHS pigs was higher than that of MHR pigs. However, in samples taken 4 h p.m. Ca2+ ATPase activity of MHS pigs has declined to about 30% of the value at 0 h; (v) The CRC can be closed and opened in all samples up to 22 h p.m. and seems to be fully functional at all sampling times; (vi) The CRC of MHS pigs is almost fully open, whereas the CRC of MHR pigs is only partially open at all sampling times; (vii) The permeability of the SR membrane to Ca2+ (determined as the ratio of SR Ca2+ ATPase with and without ionophore A23187) is the same in both MHS and MHR and did not change with ongoing time; (viii) No uncoupling of uptake from ATP hydrolysis occurred up to 4 h p.m., but the coupling differed between MHS and MHR for all time intervals with lower values for MHS pigs. The results suggest that the decreasing Ca2+ uptake rate of homogenates, sampled at different times p.m., is essentially caused by changes in the Ca2+ pump and not by changes in the CRC or an increased phospholipid membrane permeability to Ca2+.
Mol Cell Biochem 1999 May
PMID:Post mortem changes in Ca2+ transporting proteins of sarcoplasmic reticulum in dependence on malignant hyperthermia status in pigs. 1039 67

Malignant hyperthermia (MH) in man is an autosomal dominant disorder of skeletal muscle Ca(2+)-regulation. During anesthesia in predisposed individuals, it is triggered by volatile anesthetics and depolarizing muscle relaxants. In >50% of the families, MH susceptibility is linked to the gene encoding the skeletal muscle ryanodine receptor (RYR1), the calcium release channel of the sarcoplasmic reticulum, on chromosome 19q12-13.2. To date, 21 RYR1 mutations have been identified in a number of pedigrees. Four of them are also associated with central core disease (CCD), a congenital myopathy. Screening for these 21 mutations in 105 MH families including 10 CCD families phenotyped by the in vitro contracture test (IVCT) according to the European protocol revealed the following approximate distribution: 9% Arg-614-Cys, 1% Arg-614-Leu, 1% Arg-2163-Cys, 1% Val-2168-Met, 3% Thr-2206-Met and 7% Gly-2434-Arg. In one CCD family, the disease was caused by a recently reported MH mutation, Arg-2454-His. Two novel mutations, Thr-2206-Arg and Arg-2454-Cys were detected, each in a single pedigree. In the 109 individuals of the 25 families with RYR1 mutations cosegregation between genetic result and IVCT was almost perfect, only three genotypes were discordant with the IVCT phenotypes, suggesting a true sensitivity of 98.5% and a specificity of minimally 81.8% for this test. Screening of the transmembraneous region of RYR1 did not yield a new mutation confirming the cytosolic portion of the protein to be of main functional importance for disease pathogenesis.
Hum Mol Genet 1999 Oct
PMID:Screening of the ryanodine receptor gene in 105 malignant hyperthermia families: novel mutations and concordance with the in vitro contracture test. 1048 75


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