OBJECTIVE: To explore the clinical and genetic characteristics of five children with Catecholaminergic polymorphic ventricular tachycardia (CPVT). METHODS: Five children with clinical manifestations consistent with CPVT admitted to the Department of Cardiology of Children's Hospital Affiliated to Zhengzhou University from November 2019 to November 2021 were selected as the study subjects. Their clinical data were collected. Potential variants were detected by whole exome sequencing, and Sanger sequencing was used to verify the candidate variants. All patients were treated with β-blocker propranolol and followed up. RESULTS: All patients had developed the disease during exercise and presented with syncope as the initial clinical manifestation. Electrocardiogram showed sinus bradycardia. The first onset age of the 5 patients were (10.4 ± 2.19) years, and the time of delayed diagnosis was (1.6 ± 2.19) years. All of the children were found to harbor de novo heterozygous missense variants of the RYR2 gene, including c.6916G>A (p.V2306I), c.527G>C (p.R176P), c.12271G>A (p.A4091T), c.506G>T (p.R169L) and c.6817G>A (p.G2273R). Among these, c.527G>C (p.R176P) and c.6817G>A (p.G2273R) were unreported previously. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), the c.527G>C (p.R176P) was classified as a pathogenic variant (PS2+PM1+PM2_Supporting+PM5+PP3+PP4), and the c.6817G>A (p.G2273R) was classified as a likely pathogenic variant (PS2+PM2_Supporting+PP3+PP4). The symptoms of all children were significantly improved with the propranolol treatment, and none has developed syncope during the follow up. CONCLUSION Discovery of the c.527G>C (p.R176P) and c.6817G>A (p.G2273R) variants has expanded the mutational spectrum of the RYR2 gene. Genetic testing of CPVT patients can clarify the cause of the disease and provide a reference for their genetic counseling.
Child ; Humans ; Mutation ; Propranolol ; Ryanodine Receptor Calcium Release Channel/genetics* ; Syncope ; Tachycardia, Ventricular/diagnosis* ; United States

Humans ; Cardiomyopathy, Hypertrophic/genetics* ; Mutation ; Phenotype ; Ryanodine Receptor Calcium Release Channel/genetics* ; Tachycardia, Ventricular/genetics*

Humans ; Cardiomyopathy, Hypertrophic/genetics* ; Mutation ; Phenotype ; Ryanodine Receptor Calcium Release Channel/genetics* ; Tachycardia, Ventricular/genetics*

Electrocardiography ; Humans ; Mutation ; Phosphorylation ; Ryanodine Receptor Calcium Release Channel/genetics* ; Tachycardia, Ventricular/genetics*

PURPOSE: The underlying cause of myasthenia gravis (MG) is unknown, although it likely involves a genetic component. However, no common genetic variants have been unequivocally linked to autoimmune MG. We sought to identify the genetic variants associated with an increased or decreased risk of developing MG in samples from a Korean Multicenter MG Cohort. MATERIALS AND METHODS: To determine new genetic targets related to autoimmune MG, a whole genome-based single nucleotide polymorphisms (SNP) analysis was conducted using an Axiom(TM) Genome-Wide ASI 1 Array, comprising 598375 SNPs and samples from 109 MG patients and 150 neurologically normal controls. RESULTS: In total, 641 SNPs from five case-control associations showed p-values of less than 10(-5). From regional analysis, we selected seven candidate genes (RYR3, CACNA1S, SLAMF1, SOX5, FHOD3, GABRB1, and SACS) for further analysis. CONCLUSION: The present study suggests that a few genetic polymorphisms, such as in RYR3, CACNA1S, and SLAMF1, might be related to autoimmune MG. Our findings also encourage further studies, particularly confirmatory studies with larger samples, to validate and analyze the association between these SNPs and autoimmune MG.
Antigens, CD/genetics ; Asian Continental Ancestry Group/genetics ; Calcium Channels/genetics ; Female ; Genetic Predisposition to Disease/genetics ; Genotype ; Humans ; Male ; Myasthenia Gravis/*etiology ; Polymorphism, Single Nucleotide/genetics ; Receptors, Cell Surface/genetics ; Ryanodine Receptor Calcium Release Channel/genetics

OBJECTIVETo investigate changes in adenosine triphosphatase (ATPase) activity and expression of ryanodine receptor 1 (RyR1) mRNA in formation of pressure ulcer at early stage, and to analyze its mechanism.

METHODSThirty-six male Sprague-Dawley rats were divided into three groups according to the random number table as follows, with 12 rats in each group. (1) Ischemia-reperfusion (IR) for 3 times (3IR) group: unilateral gracilis of rats were loaded with 22.47 kPa pressure with a special pressure apparatus for 2.0 h to simulate ischemia, and unloaded for 0.5 h to simulate reperfusion. All rats were treated with above-mentioned manoeuvre for 3 times. (2) IR for 5 times (5IR) group: rats were treated with the same manoeuvre as that in 3IR group except for IR for 5 times. (3) CONTROL GROUP: gracilis of rats were subjected to a load of 0 kPa pressure. Rats in 3IR, 5IR groups were sacrificed, and then central part of pressured tissue was harvested for detection of activity of total ATPase, Ca(2+)-Mg(2+)-ATPase, and Na(+)-K(+)-ATPase with spectrophotometer colorimetry, the level of malondialdehyde (MDA) with enzyme linked immunosorbent assay (ELISA), and the level of RyR1 mRNA with real-time fluorescence quantitative RT-PCR. The same part of gracilis muscle of rats in control group was harvested for determination of indexes as above. Data were processed with one-way analysis of variance. Pearson correlation analysis was respectively performed between total ATPase activity and MDA level, total ATPase activity and RyR1 mRNA expression level, and RyR1 mRNA expression level and MDA level.

RESULTSActivity of total ATPase, Ca(2+)-Mg(2+)-ATPase, Na(+)-K(+)-ATPase in control group was respectively (1.629 ± 0.004), (0.907 ± 0.061), (0.697 ± 0.083) U/mg, all significantly higher than those in 3IR group [(1.365 ± 0.004), (0.784 ± 0.020), (0.581 ± 0.017) U/mg, with F value respectively 1707.0, 29.8, 15.2, P < 0.05 or P < 0.01] and 5IR group [(1.055 ± 0.049), (0.619 ± 0.016), (0.436 ± 0.039) U/mg, with F value respectively 1107.0, 169.9, 65.7, P values all below 0.01], and the values of 3 indexes in 5IR group were obviously lower than those in 3IR group (with F value respectively 322.8, 341.7, 94.0, P values all below 0.01). The level of MDA in control group [(7.5 ± 0.6) nmol/L] was lower than that in 3IR group [(9.9 ± 0.6) nmol/L, F = 53.2, P < 0.01] and 5IR group [(13.7 ± 1.3) nmol/L, F = 76.9, P < 0.01]. There was also statistical difference in MDA level between 3IR group and 5IR group (F = 82.9, P < 0.01). Expression level of RyR1 mRNA in control group (8.5 ± 4.2), which was similar to that in 3IR group (3.3 ± 2.1, F = 0.9, P > 0.05), was significantly higher than that in 5IR group (0.6 ± 0.5, F = 23.6, P < 0.05); while the RyR1 mRNA expression level was lower in 5IR group than in 3IR group (F = 39.3,P < 0.05). Activity of total ATPase was negatively correlated with MDA level (r = -0.918, P < 0.01). Activity of total ATPase was positively correlated with RyR1 mRNA expression level (r = 0.713, P < 0.01). RyR1 mRNA expression level was negatively correlated with MDA level (r = -0.702, P < 0.01).

CONCLUSIONSEnergy dysbolism may be an initial factor in the development of pressure ulcer at early stage. Calcium overload injury in pressure tissue can be identified by determination of RyR1 mRNA expression.

Adenosine Triphosphatases ; metabolism ; Animals ; Male ; Muscle, Skeletal ; metabolism ; Pressure Ulcer ; metabolism ; RNA, Messenger ; genetics ; Rats ; Rats, Sprague-Dawley ; Ryanodine Receptor Calcium Release Channel ; genetics ; metabolism

BACKGROUND: Malignant hyperthermia (MH) is genetically heterogeneous, with mutations in the gene encoding the skeletal muscle ryanodine receptor (RYR1) at 19q13.1 accounting for up to 80% of the cases. However, the search for known and novel mutations in the RYR1 gene is hampered by the fact that the gene contains 106 exons. We aimed to analyze mutations from the entire RYR1 coding region in Korean MH families. METHODS: We investigated seven affected MH individuals and their family members. The entire RYR1 coding region from the genomic DNA was sequenced, and RYR1 haplotyping and mutational analysis were carried out. RESULTS: We identified nine different RYR1 mutations or variations from seven Korean MH families. Among these, five previously reported mutations (p.Gly248Arg, p.Arg2435His, p.Arg2458His, p.Arg2676Trp, and p.Leu4838Val) and four novel variations of unknown significance (p.Arg2508Cys, p.Met4022Val, p.Glu2669Lys, and p.Ala4295Val) were identified. In two families, two variations (R2676W & M4022V, R2435H & A4295V, respectively) were identified simultaneously. Four of the observed nine mutations or variations were located outside the hotspot region of RYR1 mutations. CONCLUSIONS: These data indicate that RYR1 is a main candidate gene in Korean MH families, and that comprehensive screening of the entire coding sequence of the RYR1 gene is necessary for molecular genetic investigations in MH-susceptible individuals, owing to the presence of RYR1 mutations or variations outside of the hotspot region.
Adult ; Asian Continental Ancestry Group/*genetics ; Child ; DNA Mutational Analysis ; Exons ; Female ; Genetic Predisposition to Disease ; Haplotypes ; Humans ; Male ; Malignant Hyperthermia/*genetics ; Middle Aged ; Mutation, Missense ; Pedigree ; Republic of Korea ; Ryanodine Receptor Calcium Release Channel/*genetics ; Sequence Analysis, DNA

During membrane depolarization associated with skeletal excitation-contraction (EC) coupling, dihydropyridine receptor [DHPR, a L-type Ca2+ channel in the transverse (t)-tubule membrane] undergoes conformational changes that are transmitted to ryanodine receptor 1 [RyR1, an internal Ca2+-release channel in the sarcoplasmic reticulum (SR) membrane] causing Ca2+ release from the SR. Canonical-type transient receptor potential cation channel 3 (TRPC3), an extracellular Ca2+-entry channel in the t-tubule and plasma membrane, is required for full-gain of skeletal EC coupling. To examine additional role(s) for TRPC3 in skeletal muscle other than mediation of EC coupling, in the present study, we created a stable myoblast line with reduced TRPC3 expression and without alpha1SDHPR (MDG/TRPC3 KD myoblast) by knock-down of TRPC3 in alpha1SDHPR-null muscular dysgenic (MDG) myoblasts using retrovirus-delivered small interference RNAs in order to eliminate any DHPR-associated EC coupling-related events. Unlike wild-type or alpha1SDHPR-null MDG myoblasts, MDG/TRPC3 KD myoblasts exhibited dramatic changes in cellular morphology (e.g., unusual expansion of both cell volume and the plasma membrane, and multi-nuclei) and failed to differentiate into myotubes possibly due to increased Ca2+ content in the SR. These results suggest that TRPC3 plays an important role in the maintenance of skeletal muscle myoblasts and myotubes.
Animals ; Calcium/metabolism ; Calcium Channels/metabolism ; Calcium Channels, L-Type/genetics/metabolism ; Cations/metabolism ; *Cell Differentiation ; *Cell Proliferation ; Cells, Cultured ; Excitation Contraction Coupling ; Gene Knockdown Techniques ; Membrane Potentials ; Mice ; Muscle Fibers, Skeletal/*metabolism ; Muscle Proteins/metabolism ; Myoblasts, Skeletal/*metabolism ; Ryanodine Receptor Calcium Release Channel/metabolism ; Sarcoplasmic Reticulum/*physiology ; Synaptophysin/metabolism ; TRPC Cation Channels/genetics/*metabolism ; Transient Receptor Potential Channels/metabolism

BACKGROUND/AIMS: Underlying cardiac pathology and atrial fibrillation (AF) affect the molecular remodeling of ion channels in the atria. Changes in the expression of these molecules have not been demonstrated in Korean patients with mitral valvular heart disease. Thus, the purpose of this study was to analyze ion channel expression in patients with chronic AF and mitral valvular heart disease. METHODS: A total of 17 patients (eight males and nine females; mean age, 57 +/- 14 years [range, 19 to 77]) undergoing open-heart surgery were included in the study. Twelve patients (seven with coronary artery disease and five with aortic valvular disease) had sinus rhythm, and five patients (all with mitral valvular disease) had chronic, permanent AF. A piece of right atrial appendage tissue (0.5 g) was obtained during surgery. RT-PCR was used to evaluate the expression of L-type Ca2+ channels, ryanodine receptor (RyR2), sarcoplasmic reticular Ca2+-ATPase (SERCA2), gene encoding the rapid component of the delayed rectifier Ikr (HERG), gene encoding calcium-independent transient outward current I(to1) (Kv4.3), gene encoding the ultrarapid component of the delayed rectifier Iku (Kv1.5), K+ channel-interacting protein 2 (KChIP2), hyperpolarization-activated cation channel 2 associated with the pacemaker current If (HCN2), and gene encoding Na+ channel (SCN5A). RESULTS: Reduced L-type Ca2+ channel, RyR2, SERCA2, Kv1.5, and KChIP2 expression and borderline increased HCN2 expression were observed in the patients with AF and mitral valvular heart disease. Left atrial diameter was negatively correlated with RyR2 and KChIP2 expression. Fractional area shortening of the left atrium was positively correlated with RyR2 and KChIP2 expression. CONCLUSIONS: Alterations in ion channel expression and the anatomical substrate may favor the initiation and maintenance of AF in patients with mitral valvular heart disease.
Adult ; Aged ; Aortic Valve Stenosis/metabolism ; Atrial Fibrillation/*metabolism ; Calcium/metabolism ; Chronic Disease ; Coronary Artery Disease/metabolism ; Female ; Heart Valve Diseases/*metabolism ; Humans ; Ion Channels/*genetics ; Male ; Middle Aged ; *Mitral Valve ; Potassium Channels/genetics ; Ryanodine Receptor Calcium Release Channel/genetics ; Sodium Channels/genetics

OBJECTIVESTo block the synthesis of ryanodine receptor 2 (RyR2) in myocardial cells by RNA interference and to investigate its biological impact on ischemia-reperfusion (I/R) in rat myocardial cells.

METHODSRat myocardial cells were isolated and cultured for an I/R model in vitro. RNA interference technique was used to block the synthesis of RyR2 in myocardial cells. Changes of LDH level, apoptosis, RyR2 mRNA expression and cytosolic Ca(2+) concentration were analyzed accordingly.

RESULTSMyocardial cells after I/R manipolation were severely injuried (LDH leakage, 125 IU/L vs 12 IU/L, P < 0.05), apoptosis (60.1% vs 5.5%, P < 0.05), significant cytosolic Ca(2+) overload (21.2 vs 7.6, P < 0.05) and remarkable mitochondrial membrane potential loss (37.2 vs 85.1, P < 0.05). However, no visible change of RyR2 was observed (20.1 vs 22.7, P > 0.05). Pre-treatment with RyR2 specified siRNA demonstrated suppressed expression of RyR2 (6.8 vs 20.1, P < 0.05), increased mitochondrial membrane potential (55.8 vs 37.2, P < 0.05), attenuated cytosolic Ca(2+) overload (8.6 vs 21.2) and cellular apoptosis (31.2% vs 60.1%, P < 0.05).

CONCLUSIONRyR2 gene silencing enables to protect myocardial cells from I/R injury in vitro.

Animals ; Apoptosis ; drug effects ; genetics ; Cells, Cultured ; Gene Silencing ; immunology ; physiology ; Membrane Potential, Mitochondrial ; drug effects ; immunology ; Myocardial Reperfusion Injury ; immunology ; pathology ; Myocytes, Cardiac ; drug effects ; pathology ; Oxygen ; metabolism ; RNA Interference ; RNA, Small Interfering ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Reperfusion Injury ; immunology ; pathology ; Ryanodine Receptor Calcium Release Channel ; drug effects ; genetics