Takashi Kondo1, Toshimichi Yasuda2, Keiko Mukaida3, Sachiko Otsuki4, Rieko Kanzaki4, Hirotsugu Miyoshi4, Hiroshi Hamada2, Ichizo Nishino5, Masashi Kawamoto2. 1. Department of Anesthesiology and Critical Care, Hiroshima University Hospital, 1-2-3 Kasumi, Minami-ku, Hiroshima, 734-8551, Japan. kondo320@hiroshima-u.ac.jp. 2. Department of Anesthesiology and Critical Care, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima, Japan. 3. Department of Anesthesiology, Hiroshima Prefectural Rehabilitation Center, Higashi, Hiroshima, Japan. 4. Department of Anesthesiology and Critical Care, Hiroshima University Hospital, 1-2-3 Kasumi, Minami-ku, Hiroshima, 734-8551, Japan. 5. Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Kodaira, Japan.
Abstract
PURPOSE: The aim of this study was to analyze the genetic and functional role of a novel RYR1 variant c.251 C > T (p.Thr84Met) identified in a patient with muscle weakness demonstrating MH susceptibility. METHODS: DNA testing of family members was conducted for assessment of pathogenicity of the genetic variant. For functional analysis, Ca2+ measurement using patient-derived myotubes and p.Thr84Met RYR1-transfected human embryonic kidney (HEK)-293 cells was performed to evaluate reactivity to RYR1 activators. The half-maximal effective concentration (EC50) values of two RYR1 activators, caffeine and 4-chloro-m-cresol (4CmC), were calculated from the acquired dose-response curves. The EC50 was compared between two groups: for myotubes, the control group and the patient, and for HEK-293 cells, WT and p.Thr84Met. RESULTS: Dose-response curves for caffeine and 4CmC were shifted to the left in both myotubes and HEK-293 cells compared to controls. The 50% effective concentration values for caffeine and 4CmC were significantly lower in both myotubes and HEK-293 cells compared to controls (P < 0.001 for all comparisons). CONCLUSIONS: Our results of functional testing indicated RYR1 hypersensitivity to caffeine and 4CmC. We conclude that the genetic variant was associated with MH susceptibility.
PURPOSE: The aim of this study was to analyze the genetic and functional role of a novel RYR1 variant c.251 C > T (p.Thr84Met) identified in a patient with muscle weakness demonstrating MH susceptibility. METHODS: DNA testing of family members was conducted for assessment of pathogenicity of the genetic variant. For functional analysis, Ca2+ measurement using patient-derived myotubes and p.Thr84MetRYR1-transfected humanembryonic kidney (HEK)-293 cells was performed to evaluate reactivity to RYR1 activators. The half-maximal effective concentration (EC50) values of two RYR1 activators, caffeine and 4-chloro-m-cresol (4CmC), were calculated from the acquired dose-response curves. The EC50 was compared between two groups: for myotubes, the control group and the patient, and for HEK-293 cells, WT and p.Thr84Met. RESULTS: Dose-response curves for caffeine and 4CmC were shifted to the left in both myotubes and HEK-293 cells compared to controls. The 50% effective concentration values for caffeine and 4CmC were significantly lower in both myotubes and HEK-293 cells compared to controls (P < 0.001 for all comparisons). CONCLUSIONS: Our results of functional testing indicated RYR1hypersensitivity to caffeine and 4CmC. We conclude that the genetic variant was associated with MH susceptibility.
Authors: C A Sewry; C Müller; M Davis; J S M Dwyer; J Dove; G Evans; R Schröder; D Fürst; T Helliwell; N Laing; R C M Quinlivan Journal: Neuromuscul Disord Date: 2002-12 Impact factor: 4.296
Authors: William J Durham; Paula Aracena-Parks; Cheng Long; Ann E Rossi; Sanjeewa A Goonasekera; Simona Boncompagni; Daniel L Galvan; Charles P Gilman; Mariah R Baker; Natalia Shirokova; Feliciano Protasi; Robert Dirksen; Susan L Hamilton Journal: Cell Date: 2008-04-04 Impact factor: 41.582
Authors: M Davis; R Brown; A Dickson; H Horton; D James; N Laing; R Marston; M Norgate; D Perlman; N Pollock; K Stowell Journal: Br J Anaesth Date: 2002-04 Impact factor: 9.166