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Miura A, Yamamoto T, Funayama K, Koyama A, Takatsuka H, Sato T, Nishio H. Postmortem Identification of Genetic Variations Associated with Sudden Unexpected Death in Young People. Int Heart J 2024; 65:55-62. [PMID: 38296580 DOI: 10.1536/ihj.23-252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2024]
Abstract
Sudden unexpected death in the young (SUDY) is a traumatic occurrence for their family; however, information on the genetic variations associated with the condition is currently lacking. It is important to carry out postmortem genetic analyses in cases of sudden death to provide information for relatives and to allow appropriate genetic counselling and clinical follow-up. This study aimed to investigate the genetic variations associated with the occurrence of SUDY in Japan, using next-generation sequencing (NGS). The study included 18 cases of SUDY (16 males, 2 females; age 15-47 years) who underwent autopsy, including NGS DNA sequencing for molecular analysis. A total of 168 genes were selected from the sequencing panel and filtered, resulting in the identification of 60 variants in cardiac disease-related genes. Many of the cases had several of these genetic variants and some cases had a cardiac phenotype. The identification of genetic variants using NGS provides important information regarding the pathogenicity of sudden death.
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Affiliation(s)
- Aya Miura
- Department of Legal Medicine, Hyogo Medical University
| | | | - Kazuhisa Funayama
- Division of Legal Medicine, Department of Community Preventive Medicine, Niigata University Graduate School of Medicine and Dental Sciences
| | - Akihide Koyama
- Division of Legal Medicine, Department of Community Preventive Medicine, Niigata University Graduate School of Medicine and Dental Sciences
| | - Hisakazu Takatsuka
- Division of Legal Medicine, Department of Community Preventive Medicine, Niigata University Graduate School of Medicine and Dental Sciences
| | - Takako Sato
- Department of Legal Medicine, Osaka Medical and Pharmaceutical University, Osaka
| | - Hajime Nishio
- Department of Legal Medicine, Hyogo Medical University
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Wu J, Sakaguchi T, Takenaka K, Toyoda F, Tsuji K, Matsuura H, Horie M. A trafficking-deficient KCNQ1 mutation, T587M, causes a severe phenotype of long QT syndrome by interfering with intracellular hERG transport. J Cardiol 2019; 73:343-350. [DOI: 10.1016/j.jjcc.2018.10.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 09/11/2018] [Accepted: 10/24/2018] [Indexed: 11/29/2022]
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Fukumoto D, Ding WG, Wada Y, Fujii Y, Ichikawa M, Takayama K, Fukuyama M, Kato K, Itoh H, Makiyama T, Omatsu-Kanbe M, Matsuura H, Horie M, Ohno S. Novel intracellular transport-refractory mutations in KCNH2 identified in patients with symptomatic long QT syndrome. J Cardiol 2017; 71:401-408. [PMID: 29146210 DOI: 10.1016/j.jjcc.2017.10.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2017] [Revised: 09/29/2017] [Accepted: 10/10/2017] [Indexed: 01/30/2023]
Abstract
BACKGROUND Missense mutations in KCNH2, a gene encoding the Kv11.1 channel, cause long QT syndrome (LQTS) type 2 primarily by disrupting the intracellular transport of Kv11.1 to the plasma membrane. The present study aimed to clarify the functional changes by two novel KCNH2 missense mutations. METHODS We performed genetic screening of three unrelated symptomatic LQTS probands with family histories of cardiac symptoms. Chinese hamster ovary cells were transfected with wild-type (WT) and/or mutant KCNH2 plasmid and examined by patch-clamp technique. Immunostaining and confocal microscopy were performed to evaluate the intracellular localization of WT and homozygous mutant Kv11.1 in human embryonic kidney cells. For the study of trafficking rescue, we used low-temperature incubation (30°C). We also examined pharmacological rescue of homozygous mutant Kv11.1 current in cells treated with E-4031 or dofetilide. RESULTS We identified two novel KCNH2 missense mutations, G785D and T826I. Electrophysiological study showed that both mutant channels were nonfunctional in homozygous condition and reduced current densities by half in heterozygous condition compared with WT Kv11.1. Heterozygous Kv11.1-G785D produced a significant positive shift in activation and a significant negative shift in inactivation, whereas heterozygous Kv11.1-T826I caused no kinetic changes. Immunostaining revealed that both were transport-refractory mutations. Incubation at 30°C rescued plasma membrane expression of Kv11.1-T826I but not G785D. We confirmed low-temperature-induced restoration of homozygous Kv11.1-T826I transport by functional current measurements. In contrast, incubation with E-4031 or dofetilide failed to produce measurable currents in both homozygous mutant channels. CONCLUSIONS Two novel KCNH2 mutations disrupted the intracellular transport of Kv11.1. Low-temperature incubation rescued plasma membrane expression of Kv11.1-T826I but not G785D. Both mutations exerted loss-of-function effects on Kv11.1 and explained the phenotypes of the mutation carriers.
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Affiliation(s)
- Daisuke Fukumoto
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Otsu, Shiga, Japan
| | - Wei-Guang Ding
- Department of Physiology, Division of Cell Physiology, Shiga University of Medical Science, Otsu, Shiga, Japan
| | - Yuko Wada
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Otsu, Shiga, Japan
| | - Yusuke Fujii
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Otsu, Shiga, Japan
| | - Mari Ichikawa
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Otsu, Shiga, Japan
| | - Koichiro Takayama
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Otsu, Shiga, Japan
| | - Megumi Fukuyama
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Otsu, Shiga, Japan
| | - Koichi Kato
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Otsu, Shiga, Japan
| | - Hideki Itoh
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Otsu, Shiga, Japan
| | - Takeru Makiyama
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Mariko Omatsu-Kanbe
- Department of Physiology, Division of Cell Physiology, Shiga University of Medical Science, Otsu, Shiga, Japan
| | - Hiroshi Matsuura
- Department of Physiology, Division of Cell Physiology, Shiga University of Medical Science, Otsu, Shiga, Japan
| | - Minoru Horie
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Otsu, Shiga, Japan
| | - Seiko Ohno
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Otsu, Shiga, Japan; Center for Epidemiologic Research in Asia, Shiga University of Medical Science, Otsu, Shiga, Japan.
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