著者

Megumi Fukuyama Minoru Horie Koichi Kato Hisaaki Aoki Shuhei Fujita Yoko Yoshida Hisanori Sakazaki Takako Toda Michihiko Ueno Gaku Izumi Nobuo Momoi Jun Muneuchi Takeru Makiyama Yoshihisa Nakagawa Seiko Ohno

出版者

The Japanese Circulation Society

雑誌

Circulation Journal (ISSN:13469843)

巻号頁・発行日

pp.CJ-23-0195, (Released:2023-06-28)

参考文献数

38

被引用文献数

1

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Background: Cardiac calmodulinopathy, characterized by a life-threatening arrhythmia and sudden death in the young, is extremely rare and caused by genes encoding calmodulin, namely calmodulin 1 (CALM1), CALM2, and CALM3.Methods and Results: We screened 195 symptomatic children (age 0–12 years) who were suspected of inherited arrhythmias for 48 candidate genes, using a next-generation sequencer. Ten probands were identified as carrying variants in any of CALM1–3 (5%; median age 5 years), who were initially diagnosed with long QT syndrome (LQTS; n=5), catecholaminergic polymorphic ventricular tachycardia (CPVT; n=3), and overlap syndrome (n=2). Two probands harbored a CALM1 variant and 8 probands harbored 6 CALM2 variants. There were 4 clinical phenotypes: (1) documented lethal arrhythmic events (LAEs): 4 carriers of N98S in CALM1 or CALM2; (2) suspected LAEs: CALM2 p.D96G and D132G carriers experienced syncope and transient cardiopulmonary arrest under emotional stimulation; (3) critical cardiac complication: CALM2 p.D96V and p.E141K carriers showed severe cardiac dysfunction with QTc prolongation; and (4) neurological and developmental disorders: 2 carriers of CALM2 p.E46K showed cardiac phenotypes of CPVT. Beta-blocker therapy was effective in all cases except cardiac dysfunction, especially in combination with flecainide (CPVT-like phenotype) and mexiletine (LQTS-like).Conclusions: Calmodulinopathy patients presented severe cardiac features, and their onset of LAEs was earlier in life, requiring diagnosis and treatment at the earliest age possible.

著者

Mari Ichikawa Takeshi Aiba Seiko Ohno Daichi Shigemizu Junichi Ozawa Keiko Sonoda Megumi Fukuyama Hideki Itoh Yoshihiro Miyamoto Tatsuhiko Tsunoda Takeru Makiyama Toshihiro Tanaka Wataru Shimizu Minoru Horie

出版者

日本循環器学会

雑誌

Circulation Journal (ISSN:13469843)

巻号頁・発行日

pp.CJ-16-0486, (Released:2016-10-25)

参考文献数

33

被引用文献数

1 17

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Background:Mutations inANK2have been reported to cause various arrhythmia phenotypes. The prevalence ofANK2mutation carriers in inherited primary arrhythmia syndrome (IPAS), however, remains unknown in Japanese. Using a next-generation sequencer, we aimed to identifyANK2mutations in our cohort of IPAS patients, in whom conventional Sanger sequencing failed to identify pathogenic mutations in major causative genes, and to assess the clinical characteristics ofANK2mutation carriers.Methods and Results:We screened 535 probands with IPAS and analyzed 46 genes including wholeANK2exons using a bench-top NGS (MiSeq, Illumina) or performed whole-exome-sequencing using HiSeq2000 (Illumina). As a result, 12 of 535 probands (2.2%, aged 0–61 years, 5 males) were found to carry 7 different heterozygousANK2mutations.ANK2-W1535R was identified in 5 LQTS patients and 1 symptomatic BrS and was predicted as damaging by multiple prediction software. In total, as to phenotype, there were 8 LQTS, 2 BrS, 1 IVF, and 1 SSS/AF. Surprisingly, 4/8 LQTS patients had the acquired type of LQTS (aLQTS) and suffered torsades de pointes. A total of 7 of 12 patients had documented malignant ventricular tachyarrhythmias.Conclusions:VariousANK2mutations are associated with a wide range of phenotypes, including aLQTS, especially with ventricular fibrillation, representing “ankyrin-B” syndrome.

著者

Masao Yoshinaga Yumiko Ninomiya Yuji Tanaka Megumi Fukuyama Koichi Kato Seiko Ohno Minoru Horie Hiromitsu Ogata

出版者

The Japanese Circulation Society

雑誌

Circulation Journal (ISSN:13469843)

巻号頁・発行日

pp.CJ-23-0409, (Released:2023-12-01)

参考文献数

32

被引用文献数

1

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Background: This study was performed to clarify the clinical findings of pediatric patients diagnosed with long QT syndrome (LQTS) through electrocardiographic screening programs and to predict their outcome using Holter electrocardiographic approaches.Methods and Results: This retrospective study included pediatric patients with a Schwartz score of ≥3.5 who visited the National Hospital Organization Kagoshima Medical Center between April 2005 and March 2019. Resting 12-lead and Holter electrocardiograms were recorded at every visit. The maximum resting QTc and maximum Holter QTc values among all recordings were used for statistical analyses. To test the prognostic value of QTc for the appearance of cardiac events after the first hospital visit, receiver operating characteristic curves were used to calculate the area under the curve (AUC). Among 207 patients, 181 (87%) were diagnosed through screening programs. The prevalence of cardiac events after the first hospital visit was 4% (8/207). Among QTc at diagnosis, maximum resting QTc, and maximum Holter QTc, only maximum Holter QTc value was a predictor (P=0.02) of cardiac events after the hospital visit in multivariate regression analysis. The AUC of the maximum Holter QTc was significantly superior to that of maximum resting QTc.Conclusions: The maximum Holter QTc value can be used to predict the appearance of symptoms in pediatric patients with LQTS.

著者

Mamoru Hayano Takeru Makiyama Tsukasa Kamakura Hiroshi Watanabe Kenichi Sasaki Shunsuke Funakoshi Yimin Wuriyanghai Suguru Nishiuchi Takeshi Harita Yuta Yamamoto Hirohiko Kohjitani Sayako Hirose Fumika Yokoi Jiarong Chen Osamu Baba Takahiro Horie Kazuhisa Chonabayashi Seiko Ohno Futoshi Toyoda Yoshinori Yoshida Koh Ono Minoru Horie Takeshi Kimura

出版者

日本循環器学会

雑誌

Circulation Journal (ISSN:13469843)

巻号頁・発行日

pp.CJ-17-0064, (Released:2017-06-20)

参考文献数

38

被引用文献数

23

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Background:TheSCN5Agene encodes the α subunit of the cardiac voltage-gated sodium channel, NaV1.5. The missense mutation, D1275N, has been associated with a range of unusual phenotypes associated with reduced NaV1.5 function, including cardiac conduction disease and dilated cardiomyopathy. Curiously, the reported biophysical properties ofSCN5A-D1275N channels vary with experimental system.Methods and Results:First, using a human embryonic kidney (HEK) 293 cell-based heterologous expression system, theSCN5A-D1275N channels showed similar maximum sodium conductance but a significantly depolarizing shift of activation gate (+10 mV) compared to wild type. Second, we generated human-induced pluripotent stem cells (hiPSCs) from a 24-year-old female who carried heterozygousSCN5A-D1275N and analyzed the differentiated cardiomyocytes (CMs). AlthoughSCN5Atranscript levels were equivalent between D1275N and control hiPSC-CMs, both the total amount of NaV1.5 and the membrane fractions were reduced approximately half in the D1275N cells, which were rescued by the proteasome inhibitor MG132 treatment. Electrophysiological assays revealed that maximum sodium conductance was reduced to approximately half of that in control hiPSC-CMs in the D1275N cells, and maximum upstroke velocity of action potential was lower in D1275N, which was consistent with the reduced protein level of NaV1.5.Conclusions:This study successfully demonstrated diminished sodium currents resulting from lower NaV1.5 protein levels, which is dependent on proteasomal degradation, using a hiPSC-based model forSCN5A-D1275N-related sodium channelopathy.

著者

Tsukasa Kamakura Takeru Makiyama Kenichi Sasaki Yoshinori Yoshida Yimin Wuriyanghai Jiarong Chen Tetsuhisa Hattori Seiko Ohno Toru Kita Minoru Horie Shinya Yamanaka Takeshi Kimura

出版者

日本循環器学会

雑誌

Circulation Journal (ISSN:13469843)

巻号頁・発行日

pp.CJ-12-0987, (Released:2013-02-09)

参考文献数

34

被引用文献数

28 221

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Background: In the short- to mid-term, cardiomyocytes generated from human-induced pluripotent stem cells (hiPSC-CMs) have been reported to be less mature than those of adult hearts. However, the maturation process in a long-term culture remains unknown. Methods and Results: A hiPSC clone generated from a healthy control was differentiated into CMs through embryoid body (EB) formation. The ultrastructural characteristics and gene expressions of spontaneously contracting EBs were analyzed through 1-year of culture after cardiac differentiation was initiated. The 14-day-old EBs contained a low number of myofibrils, which lacked alignment, and immature high-density Z-bands lacking A-, H-, I-, and M-bands. Through the long-term culture up to 180 days, the myofibrils became more tightly packed and formed parallel arrays accompanied by the appearance of mature Z-, A-, H-, and I-bands, but not M-bands. Notably, M-bands were finally detected in 360-day-old EBs. The expression levels of the M-band-specific genes in hiPSC-CMs remained lower in comparison with those in the adult heart. Immunocytochemistry indicated increasing number of MLC2v-positive/MLC2a-negative cells with decreasing number of MLC2v/MLC2a double-positive cells, indicating maturing of ventricular-type CMs. Conclusions: The structural maturation process of hiPSC-CMs through 1-year of culture revealed ultrastructural sarcomeric changes accompanied by delayed formation of M-bands. Our study provides new insight into the maturation process of hiPSC-CMs.