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Han JY, Park J. Novel compound heterozygous mutations in SCN4A as a potential genetic cause contributing to myopathic manifestations: A case report and literature review. Heliyon 2024; 10:e28684. [PMID: 38571618 PMCID: PMC10988054 DOI: 10.1016/j.heliyon.2024.e28684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 03/13/2024] [Accepted: 03/22/2024] [Indexed: 04/05/2024] Open
Abstract
Background SCN4A mutations account for a diverse array of clinical manifestations, encompassing periodic paralysis, myotonia, and newly recognized symptoms like classical congenital myopathy or congenital myasthenic syndromes. We describe the initial occurrence of myopathic features mimic with recessive classical CM in a Korean infant presenting with novel compound heterozygous SCN4A mutations. The infant exhibited profound hypotonia after birth, thereby expanding the spectrum of SCN4A-related channelopathy. Methods The genetic analyses comprised targeted exome sequencing, employing a Celemics G-Mendeliome DES Panel, along with Sanger sequencing. Results Considering the clinical manifestations observed in the proband, SCN4A variants emerged as the primary contenders for autosomal recessive (AR) congenital myopathy 22a, classic (#620351). Sanger sequencing validated the association of SCN4A variants with the phenotype, affirming the AR nature of the compound heterozygous variants in both the carrier mother (c.3533G > T/p.Gly1178Val) and the father (c.4216G > A/p.Ala1406Thr). Conclusion Our report emphasizes the association of novel compound heterozygous mutations in SCN4A with myopathic features resembling CM, as supporting by muscle biopsy. It is essential to note that pathogenic SCN4A LoF mutations are exceedingly rare. This study contributes to our understanding of SCN4A mutations and their role in myopathic features mimic with classical CM.
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Affiliation(s)
- Ji Yoon Han
- Department of Pediatrics, College of Medicine, The Catholic University of Korea, Seoul, 06591, Republic of Korea
| | - Joonhong Park
- Department of Laboratory Medicine, Jeonbuk National University Medical School and Hospital, Jeonju, 54907, Republic of Korea
- Research Institute of Clinical Medicine of Jeonbuk National University-Biomedical Research Institute of Jeonbuk National University Hospital, Jeonju, 54907, Republic of Korea
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Min JH, Lee JY, Ahn HS, Cui HS, Seo CH, Kim JB. Prevalence and risk factors of low vitamin D levels in children and adolescents with familial hypokalemic periodic paralysis. Eur J Pediatr 2024; 183:305-311. [PMID: 37875632 DOI: 10.1007/s00431-023-05299-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 10/17/2023] [Accepted: 10/18/2023] [Indexed: 10/26/2023]
Abstract
Patients with familial hypokalemic periodic paralysis (HOKPP) experience episodes of reversible immobility and are at an increased risk of limited sunlight exposure, potentially leading to vitamin D deficiency. However, there is a lack of data on vitamin D levels in this population. We investigated serum vitamin D levels and their associated factors in children with HOKPP. This study included 170 genetically-confirmed children with HOKPP, aged 3-18 years, and 170 age-, sex-, and body mass index (BMI)-matched healthy controls from the Korean Channelopathy Study, a prospective controlled investigation. Anthropometric and clinical characteristics were recorded, and serum levels of calcium, ionized calcium, phosphorus, alkaline phosphatase, 25-hydroxyvitamin D, and intact parathyroid hormone (PTH) were analyzed. Vitamin D deficiency (< 20 ng/mL) was observed in 87.0% of the patients compared to 45.5% of the controls (P < 0.05) during the summer-fall season. During the winter-spring season, 91.7% of the patients and 73.4% of the controls were deficient (P < 0.05). A strong positive correlation was found between onset age of the first paralytic attack and vitamin D levels (r = 0.78, P < 0.01). Conversely, the frequency and duration of paralytic attacks were negatively correlated with vitamin D levels (r = -0.82 and r = -0.65, P < 0.01, respectively). Age, BMI, age at onset, frequency and duration of attacks, and PTH levels were independently associated with vitamin D levels (ß = -0.10, -0.12, 0.19, -0.27, -0.21, and -0.13, P < 0.05, respectively). CONCLUSIONS Vitamin D deficiency was highly prevalent in children with HOKPP, and vitamin D levels correlated with various disease characteristics. We recommend routine screening for vitamin D levels in these patients to address this prevalent deficiency. Considering the high prevalence of vitamin D deficiency observed, further research on other diseases characterized by reversible immobility is warranted. WHAT IS KNOWN • A correlation between immobility and low serum vitamin D levels has been established. However, the vitamin D status of patients with familial hypokalemic periodic paralysis (HOKPP) who experience periods of reversible immobility remains unknown. WHAT IS NEW • Vitamin D deficiency was highly prevalent in children with HOKPP, and vitamin D levels correlated with various disease characteristics.
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Affiliation(s)
- Jae-Hoon Min
- Department of Pediatrics, Uijeongbu Eulji Medical Center, Eulji University College of Medicine, Uijeongbu, Republic of Korea
| | - Ji Young Lee
- Department of Pediatrics, Hallym University Chuncheon Sacred Heart Hospital, Chuncheon, Republic of Korea
| | - Hye-Sung Ahn
- Department of Pediatrics, Seoul National University Boramae Medical Center, Seoul, Republic of Korea
| | - Hui Song Cui
- Department of Rehabilitation Medicine, Hallym University Hangang Sacred Heart Hospital, Seoul, Republic of Korea
| | - Cheong Hoon Seo
- Department of Rehabilitation Medicine, Hallym University Hangang Sacred Heart Hospital, Seoul, Republic of Korea.
| | - June-Bum Kim
- Department of Pediatrics, Uijeongbu Eulji Medical Center, Eulji University College of Medicine, Uijeongbu, Republic of Korea.
- Medical Genetics Clinic, Uijeongbu Eulji Medical Center, Eulji University College of Medicine, Uijeongbu, Republic of Korea.
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Kim HR, Jeon JW, Lee EJ, Ham YR, Na KR, Lee KW, Park KH, Kim SY, Choi DE. Confirming Genetic Abnormalities of Hypokalemic Periodic Paralysis Using Next-Generation Sequencing: A Case Report and Literature Review. Electrolyte Blood Press 2021; 19:10-14. [PMID: 34290819 PMCID: PMC8267070 DOI: 10.5049/ebp.2021.19.1.10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 05/12/2021] [Accepted: 05/13/2021] [Indexed: 11/05/2022] Open
Abstract
Hypokalemic periodic paralysis (hypoPP) is a disorder characterized by episodic, short-lived, and hypo-reflexive skeletal muscle weakness. HypoPP is a rare disease caused by genetic mutations related to expression of sodium or calcium ion channels. Most mutations are associated with autosomal dominant inheritance, but some are found in patients with no relevant family history. A 28-year-old man who visited the emergency room for paralytic attack was assessed in this study. He exhibited motor weakness in four limbs. There was no previous medical history or family history. The initial electrocardiogram showed a flat T wave and QT prolongation. His blood test was delayed, and sudden hypotension and bradycardia were observed. The blood test showed severe hypokalemia. After correcting hypokalemia, his muscle paralysis recovered without any neurological deficits. The patient's thyroid function and long exercise test results were normal. However, because of the history of high carbohydrate diet and exercise, hypoPP was suspected. Hence, next-generation sequencing (NGS) was performed, and a mutation of Arg669His was noted in the SCN4A gene. Although hypoPP is a rare disease, it can be suspected in patients with hypokalemic paralysis, and iden tification of this condition is important for preventing further attacks and improving patient outcomes. Diagnosing hypoPP through targeted NGS is a cost-effective and useful method.
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Affiliation(s)
- Hae Ri Kim
- Department of Internal Medicine, Division of Nephrology, Chungnam National University Sejong Hospital, Sejong, Republic of Korea
| | - Jae Wan Jeon
- Department of Internal Medicine, Division of Nephrology, Chungnam National University Sejong Hospital, Sejong, Republic of Korea
| | - Eu Jin Lee
- Department of Internal Medicine, Division of Nephrology, Chungnam National University Hospital, Daejeon, Republic of Korea
| | - Young Rok Ham
- Department of Internal Medicine, Division of Nephrology, Chungnam National University Hospital, Daejeon, Republic of Korea
| | - Ki Ryang Na
- Department of Internal Medicine, Division of Nephrology, Chungnam National University Hospital, Daejeon, Republic of Korea
| | - Kang Wook Lee
- Department of Internal Medicine, Division of Nephrology, Chungnam National University Hospital, Daejeon, Republic of Korea
| | - Kee Hong Park
- Department of Neurology, Seoul Medical Center, Seoul, Republic of Korea
| | - Seon Young Kim
- Department of Laboratory Medicine, Chungnam National University Hospital, Daejeon, Republic of Korea
| | - Dae Eun Choi
- Department of Internal Medicine, Division of Nephrology, Chungnam National University Hospital, Daejeon, Republic of Korea
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Närhi A, Fernandes A, Toiviainen-Salo S, Harris J, McInerney-Leo A, Lazarus S, Avela K, Duncan EL. A family with partially penetrant multicentric carpotarsal osteolysis due to gonadal mosaicism: First reported case. Am J Med Genet A 2021; 185:2477-2481. [PMID: 33988298 DOI: 10.1002/ajmg.a.62257] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 03/17/2021] [Accepted: 04/10/2021] [Indexed: 01/30/2023]
Abstract
Multicentric carpotarsal osteolysis (MCTO) is an autosomal dominant condition characterized by carpal-tarsal abnormalities; over half of affected individuals also develop renal disease. MCTO is caused by mutations of MAFB; however, there is no clear phenotype-genotype correlation. We describe the first reported family of variable MCTO phenotype due to mosaicism: the proband had classical skeletal features and renal involvement due to focal segmental glomerulosclerosis (FSGS), and the father had profound renal impairment due to FSGS, necessitating kidney transplantation. Mosaicism was first suspected in this family due to unequal allele ratios in the sequencing chromatograph of the initial blood sample of proband's father and confirmed by sequencing DNA extracted from the father's hair, collected from different bodily parts. This case highlights the need for a high index of clinical suspicion to detect low-level parental mosaicism, as well as a potential role for MAFB mutation screening in individuals with isolated FSGS.
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Affiliation(s)
- Anu Närhi
- Department of Clinical Genetics, Helsinki University Hospital, Helenski, Finland
| | - Andrea Fernandes
- Department of Endocrinology and Diabetes, Royal Brisbane and Women's Hospital, Herston, Australia.,Faculty of Medicine, University of Queensland, Translational Research Institute, Woolloongabba, Australia.,Faculty of Medicine, Herston, University of Queensland, Herston, Australia
| | - Sanna Toiviainen-Salo
- Department of Radiology, New Children's Hospital, Helsinki University Hospital, Helenski, Finland
| | - Jessica Harris
- University of Queensland Diamantina Institute, University of Queensland, Translational Research Institute, Princess Alexandra Hospital, Woolloongabba, Australia
| | - Aideen McInerney-Leo
- Dermatology Research Centre, University of Queensland Diamantina Institute, University of Queensland, Woolloongabba, Australia
| | - Syndia Lazarus
- Department of Endocrinology and Diabetes, Royal Brisbane and Women's Hospital, Herston, Australia.,Faculty of Medicine, Herston, University of Queensland, Herston, Australia.,Department of Internal Medicine (Endocrinology), The Prince Charles Hospital, Chermside, Australia
| | - Kristiina Avela
- Department of Clinical Genetics, Helsinki University Hospital, Helenski, Finland
| | - Emma L Duncan
- Department of Twin Research and Genetic Epidemiology, School of Life Course Sciences, Faculty of Life Sciences and Medicine, King's College London, London, UK
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Paramonov AS, Lyukmanova EN, Myshkin MY, Shulepko MA, Kulbatskii DS, Petrosian NS, Chugunov AO, Dolgikh DA, Kirpichnikov MP, Arseniev AS, Shenkarev ZO. NMR investigation of the isolated second voltage-sensing domain of human Nav1.4 channel. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1859:493-506. [PMID: 28065835 DOI: 10.1016/j.bbamem.2017.01.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 12/06/2016] [Accepted: 01/04/2017] [Indexed: 10/20/2022]
Abstract
Voltage-gated Na+ channels are essential for the functioning of cardiovascular, muscular, and nervous systems. The α-subunit of eukaryotic Na+ channel consists of ~2000 amino acid residues and encloses 24 transmembrane (TM) helices, which form five membrane domains: four voltage-sensing (VSD) and one pore domain. The structural complexity significantly impedes recombinant production and structural studies of full-sized Na+ channels. Modular organization of voltage-gated channels gives an idea for studying of the isolated second VSD of human skeletal muscle Nav1.4 channel (VSD-II). Several variants of VSD-II (~150a.a., four TM helices) with different N- and C-termini were produced by cell-free expression. Screening of membrane mimetics revealed low stability of VSD-II samples in media containing phospholipids (bicelles, nanodiscs) associated with the aggregation of electrically neutral domain molecules. The almost complete resonance assignment of 13C,15N-labeled VSD-II was obtained in LPPG micelles. The secondary structure of VSD-II showed similarity with the structures of bacterial Na+ channels. The fragment of S4 TM helix between the first and second conserved Arg residues probably adopts 310-helical conformation. Water accessibility of S3 helix, observed by the Mn2+ titration, pointed to the formation of water-filled crevices in the micelle embedded VSD-II. 15N relaxation data revealed characteristic pattern of μs-ms time scale motions in the VSD-II regions sharing expected interhelical contacts. VSD-II demonstrated enhanced mobility at ps-ns time scale as compared to isolated VSDs of K+ channels. These results validate structural studies of isolated VSDs of Na+ channels and show possible pitfalls in application of this 'divide and conquer' approach.
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Affiliation(s)
- A S Paramonov
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya str., 16/10, Moscow 117997, Russia; Lomonosov Moscow State University, Moscow 119991, Russia
| | - E N Lyukmanova
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya str., 16/10, Moscow 117997, Russia; Lomonosov Moscow State University, Moscow 119991, Russia
| | - M Yu Myshkin
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya str., 16/10, Moscow 117997, Russia; Moscow Institute of Physics and Technology (State University), Institutskiy Pereulok 9, Dolgoprudny, Moscow Region 141700, Russia
| | - M A Shulepko
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya str., 16/10, Moscow 117997, Russia; Lomonosov Moscow State University, Moscow 119991, Russia
| | - D S Kulbatskii
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya str., 16/10, Moscow 117997, Russia; Lomonosov Moscow State University, Moscow 119991, Russia
| | - N S Petrosian
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya str., 16/10, Moscow 117997, Russia; Moscow Institute of Physics and Technology (State University), Institutskiy Pereulok 9, Dolgoprudny, Moscow Region 141700, Russia
| | - A O Chugunov
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya str., 16/10, Moscow 117997, Russia
| | - D A Dolgikh
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya str., 16/10, Moscow 117997, Russia; Lomonosov Moscow State University, Moscow 119991, Russia
| | - M P Kirpichnikov
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya str., 16/10, Moscow 117997, Russia; Lomonosov Moscow State University, Moscow 119991, Russia
| | - A S Arseniev
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya str., 16/10, Moscow 117997, Russia; Moscow Institute of Physics and Technology (State University), Institutskiy Pereulok 9, Dolgoprudny, Moscow Region 141700, Russia
| | - Z O Shenkarev
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya str., 16/10, Moscow 117997, Russia; Moscow Institute of Physics and Technology (State University), Institutskiy Pereulok 9, Dolgoprudny, Moscow Region 141700, Russia.
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Imbrici P, Liantonio A, Camerino GM, De Bellis M, Camerino C, Mele A, Giustino A, Pierno S, De Luca A, Tricarico D, Desaphy JF, Conte D. Therapeutic Approaches to Genetic Ion Channelopathies and Perspectives in Drug Discovery. Front Pharmacol 2016; 7:121. [PMID: 27242528 PMCID: PMC4861771 DOI: 10.3389/fphar.2016.00121] [Citation(s) in RCA: 105] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2016] [Accepted: 04/25/2016] [Indexed: 12/21/2022] Open
Abstract
In the human genome more than 400 genes encode ion channels, which are transmembrane proteins mediating ion fluxes across membranes. Being expressed in all cell types, they are involved in almost all physiological processes, including sense perception, neurotransmission, muscle contraction, secretion, immune response, cell proliferation, and differentiation. Due to the widespread tissue distribution of ion channels and their physiological functions, mutations in genes encoding ion channel subunits, or their interacting proteins, are responsible for inherited ion channelopathies. These diseases can range from common to very rare disorders and their severity can be mild, disabling, or life-threatening. In spite of this, ion channels are the primary target of only about 5% of the marketed drugs suggesting their potential in drug discovery. The current review summarizes the therapeutic management of the principal ion channelopathies of central and peripheral nervous system, heart, kidney, bone, skeletal muscle and pancreas, resulting from mutations in calcium, sodium, potassium, and chloride ion channels. For most channelopathies the therapy is mainly empirical and symptomatic, often limited by lack of efficacy and tolerability for a significant number of patients. Other channelopathies can exploit ion channel targeted drugs, such as marketed sodium channel blockers. Developing new and more specific therapeutic approaches is therefore required. To this aim, a major advancement in the pharmacotherapy of channelopathies has been the discovery that ion channel mutations lead to change in biophysics that can in turn specifically modify the sensitivity to drugs: this opens the way to a pharmacogenetics strategy, allowing the development of a personalized therapy with increased efficacy and reduced side effects. In addition, the identification of disease modifiers in ion channelopathies appears an alternative strategy to discover novel druggable targets.
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Affiliation(s)
- Paola Imbrici
- Department of Pharmacy - Drug Sciences, University of Bari "Aldo Moro" Bari, Italy
| | - Antonella Liantonio
- Department of Pharmacy - Drug Sciences, University of Bari "Aldo Moro" Bari, Italy
| | - Giulia M Camerino
- Department of Pharmacy - Drug Sciences, University of Bari "Aldo Moro" Bari, Italy
| | - Michela De Bellis
- Department of Pharmacy - Drug Sciences, University of Bari "Aldo Moro" Bari, Italy
| | - Claudia Camerino
- Department of Basic Medical Sciences, Neurosciences and Sense Organs, University of Bari "Aldo Moro" Bari, Italy
| | - Antonietta Mele
- Department of Pharmacy - Drug Sciences, University of Bari "Aldo Moro" Bari, Italy
| | - Arcangela Giustino
- Department of Biomedical Sciences and Human Oncology, University of Bari "Aldo Moro" Bari, Italy
| | - Sabata Pierno
- Department of Pharmacy - Drug Sciences, University of Bari "Aldo Moro" Bari, Italy
| | - Annamaria De Luca
- Department of Pharmacy - Drug Sciences, University of Bari "Aldo Moro" Bari, Italy
| | - Domenico Tricarico
- Department of Pharmacy - Drug Sciences, University of Bari "Aldo Moro" Bari, Italy
| | - Jean-Francois Desaphy
- Department of Biomedical Sciences and Human Oncology, University of Bari "Aldo Moro" Bari, Italy
| | - Diana Conte
- Department of Pharmacy - Drug Sciences, University of Bari "Aldo Moro" Bari, Italy
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Wang XY, Ren BW, Yong ZH, Xu HY, Fu QX, Yao HB. Mutation analysis of CACNA1S and SCN4A in patients with hypokalemic periodic paralysis. Mol Med Rep 2015; 12:6267-74. [PMID: 26252573 DOI: 10.3892/mmr.2015.4201] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Accepted: 07/22/2015] [Indexed: 11/05/2022] Open
Abstract
Mutations in CACNA1S (calcium channel, voltage‑dependent, L type, alpha 1S subunit) and SCN4A (sodium channel, voltage‑gated, type IV, alpha subunit) are associated with hypokalemic periodic paralysis (HPP). The aim of the current study was to investigate CACNA1S and SCN4A mutations in patients with HPP. Mutations in CACNA1S and SCN4A were detected in three familial hypokalemic periodic paralysis (FHPP) pedigrees and in two thyrotoxic hypokalemic periodic paralysis (THPP) pedigrees using polymerase chain reaction, DNA sequencing and sequence alignment with GenBank data. A single base mutation from cytosine to guanine at site 1582 was identified in exon 11 of CACNA1S in one FHPP pedigree, resulting in an arginine to glycine (R528G) substitution. A single base mutation from thymine to cytosine at site 2012 was identified in exon 12 of SCN4A in one THPP pedigree, resulting in a phenylalanine to serine (F671S) substitution. No mutations in CACNA1S or SCN4A were identified in the remaining three pedigrees. The present study indicated that CACNA1S and SCN4A mutations are relatively rare in patients with HPP, and further studies are required to determine whether these mutation‑associated substitutions are representative of patients with HPP.
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Affiliation(s)
- Xiao-Ying Wang
- Department of Endocrinology, Chinese People's Liberation Army Navy General Hospital, Beijing 100048, P.R. China
| | - Bing-Wen Ren
- Department of Cadres Medical Care, Chinese People's Liberation Army Navy General Hospital, Beijing 100048, P.R. China
| | - Zeng-Hua Yong
- Department of Endocrinology, Chinese People's Liberation Army Navy General Hospital, Beijing 100048, P.R. China
| | - Hong-Yan Xu
- Department of Endocrinology, Chinese People's Liberation Army Navy General Hospital, Beijing 100048, P.R. China
| | - Qiu-Xia Fu
- Department of Endocrinology, Chinese People's Liberation Army Navy General Hospital, Beijing 100048, P.R. China
| | - He-Bin Yao
- Department of Endocrinology, Chinese People's Liberation Army Navy General Hospital, Beijing 100048, P.R. China
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Kim JB, Kim SJ, Kang SY, Yi JW, Kim SM. The large-conductance calcium-activated potassium channel holds the key to the conundrum of familial hypokalemic periodic paralysis. KOREAN JOURNAL OF PEDIATRICS 2014; 57:445-50. [PMID: 25379045 PMCID: PMC4219947 DOI: 10.3345/kjp.2014.57.10.445] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Revised: 03/27/2014] [Accepted: 06/03/2014] [Indexed: 11/30/2022]
Abstract
Purpose Familial hypokalemic periodic paralysis (HOKPP) is an autosomal dominant channelopathy characterized by episodic attacks of muscle weakness and hypokalemia. Mutations in the calcium channel gene, CACNA1S, or the sodium channel gene, SCN4A, have been found to be responsible for HOKPP; however, the mechanism that causes hypokalemia remains to be determined. The aim of this study was to improve the understanding of this mechanism by investigating the expression of calcium-activated potassium (KCa) channel genes in HOKPP patients. Methods We measured the intracellular calcium concentration with fura-2-acetoxymethyl ester in skeletal muscle cells of HOKPP patients and healthy individuals. We examined the mRNA and protein expression of KCa channel genes (KCNMA1, KCNN1, KCNN2, KCNN3, and KCNN4) in both cell types. Results Patient cells exhibited higher cytosolic calcium levels than normal cells. Quantitative reverse transcription polymerase chain reaction analysis showed that the mRNA levels of the KCa channel genes did not significantly differ between patient and normal cells. However, western blot analysis showed that protein levels of the KCNMA1 gene, which encodes KCa1.1 channels (also called big potassium channels), were significantly lower in the membrane fraction and higher in the cytosolic fraction of patient cells than normal cells. When patient cells were exposed to 50 mM potassium buffer, which was used to induce depolarization, the altered subcellular distribution of BK channels remained unchanged. Conclusion These findings suggest a novel mechanism for the development of hypokalemia and paralysis in HOKPP and demonstrate a connection between disease-associated mutations in calcium/sodium channels and pathogenic changes in nonmutant potassium channels.
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Affiliation(s)
- June-Bum Kim
- Department of Pediatrics, Hallym University Hangang Sacred Heart Hospital, Seoul, Korea
| | - Sung-Jo Kim
- Department of Biotechnology, Hoseo University, Asan, Korea
| | - Sun-Yang Kang
- Department of Biotechnology, Hoseo University, Asan, Korea
| | - Jin Woong Yi
- Department of Orthopedic Surgery, Konyang University Hospital, Daejeon, Korea
| | - Seung-Min Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, Korea
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Abstract
Channelopathies are a heterogeneous group of disorders resulting from the dysfunction of ion channels located in the membranes of all cells and many cellular organelles. These include diseases of the nervous system (e.g., generalized epilepsy with febrile seizures plus, familial hemiplegic migraine, episodic ataxia, and hyperkalemic and hypokalemic periodic paralysis), the cardiovascular system (e.g., long QT syndrome, short QT syndrome, Brugada syndrome, and catecholaminergic polymorphic ventricular tachycardia), the respiratory system (e.g., cystic fibrosis), the endocrine system (e.g., neonatal diabetes mellitus, familial hyperinsulinemic hypoglycemia, thyrotoxic hypokalemic periodic paralysis, and familial hyperaldosteronism), the urinary system (e.g., Bartter syndrome, nephrogenic diabetes insipidus, autosomal-dominant polycystic kidney disease, and hypomagnesemia with secondary hypocalcemia), and the immune system (e.g., myasthenia gravis, neuromyelitis optica, Isaac syndrome, and anti-NMDA [N-methyl-D-aspartate] receptor encephalitis). The field of channelopathies is expanding rapidly, as is the utility of molecular-genetic and electrophysiological studies. This review provides a brief overview and update of channelopathies, with a focus on recent advances in the pathophysiological mechanisms that may help clinicians better understand, diagnose, and develop treatments for these diseases.
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Affiliation(s)
- June-Bum Kim
- Department of Pediatrics, Seoul Children's Hospital, Seoul, Korea
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Song YW, Kim SJ, Heo TH, Kim MH, Kim JB. Normokalemic periodic paralysis is not a distinct disease. Muscle Nerve 2012; 46:914-6. [PMID: 22926674 DOI: 10.1002/mus.23441] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/27/2012] [Indexed: 11/11/2022]
Abstract
INTRODUCTION Recent molecular studies of the original cases of normokalemic periodic paralysis (normoKPP) have raised suspicions that these families actually had hyperkalemic periodic paralysis (hyperKPP) due to mutations in the skeletal muscle sodium channel gene SCN4A. However, there is still a debate about the existence of normoKPP. METHODS We screened 230 individuals with primary periodic paralysis for mutations in the SCN4A, CACNA1S, and KCNJ2 genes. All patients had either a hyperKPP or a hypoKPP phenotype, and none had a normoKPP phenotype. RESULTS In 4 hyperKPP patients from 2 families, molecular analyses revealed Arg675Gly and Arg675Gln mutations of SCN4A, which were previously reported to cause normoKPP. Each patient exhibited the characteristic clinical and laboratory features (including hyperkalemia during spontaneous attacks) of hyperKPP. CONCLUSION Our findings support the notion that normoKPP is not a distinct disease.
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Affiliation(s)
- Young-Wha Song
- Department of Pediatrics, Konyang University Hospital, Daejun, Republic of Korea
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Chu PY, Cheng CJ, Tseng MH, Yang SS, Chen HC, Lin SH. Genetic variant rs623011 (17q24.3) associates with non-familial thyrotoxic and sporadic hypokalemic paralysis. Clin Chim Acta 2012; 414:105-8. [PMID: 22910584 DOI: 10.1016/j.cca.2012.08.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2012] [Revised: 08/01/2012] [Accepted: 08/04/2012] [Indexed: 10/28/2022]
Abstract
BACKGROUND A recent genome-wide association study of Thai patients with thyrotoxic periodic paralysis (TPP) identified a novel genetic variant rs623011 located in chromosome 17q24.3, which may potentially reduce the transcription of Kir2.1 and total Kir current. PURPOSE The aim of this study was to evaluate whether this genetic variant was present in Chinese patients with TPP and sporadic periodic paralysis (SPP), the second leading cause of non-familial hypokalemic periodic paralysis (hypoKPP) in Asia. METHODS Ninety patients with TPP, 61 SPP, and 100 age and sex-matched healthy subjects were performed. Genomic DNA was isolated from blood leukocytes and analysis of rs623011 was performed by polymerase chain reaction and direct sequencing. RESULTS Compared with normal control, the frequency of the risk allele A of rs623011 was significantly higher in both TPP and SPP patients (73.9% versus 53.5%, p=0.001; 82.0% versus 53.5%, p<0.001, respectively) with the Odds ratios (95% confidence interval) 2.426 (1.348-4.369) and 4.488 (2.265-8.891), respectively. The frequency of the A allele of rs623011 was similar between TPP and SPP. CONCLUSIONS TPP and SPP have the same susceptible gene variant rs623011 and may share the pathogenic mechanism of reduced Kir current in skeletal muscle independent of thyroid hormone.
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Affiliation(s)
- Pei-Yi Chu
- Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan
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Jurkat-Rott K, Groome J, Lehmann-Horn F. Pathophysiological role of omega pore current in channelopathies. Front Pharmacol 2012; 3:112. [PMID: 22701429 PMCID: PMC3372090 DOI: 10.3389/fphar.2012.00112] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2012] [Accepted: 05/23/2012] [Indexed: 12/12/2022] Open
Abstract
In voltage-gated cation channels, a recurrent pattern for mutations is the neutralization of positively charged residues in the voltage-sensing S4 transmembrane segments. These mutations cause dominant ion channelopathies affecting many tissues such as brain, heart, and skeletal muscle. Recent studies suggest that the pathogenesis of associated phenotypes is not limited to alterations in the gating of the ion-conducting alpha pore. Instead, aberrant so-called omega currents, facilitated by the movement of mutated S4 segments, also appear to contribute to symptoms. Surprisingly, these omega currents conduct cations with varying ion selectivity and are activated in either a hyperpolarized or depolarized voltage range. This review gives an overview of voltage sensor channelopathies in general and focuses on pathogenesis of skeletal muscle S4 disorders for which current knowledge is most advanced.
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Han JY, Kim JB. Familial hyperkalemic periodic paralysis caused by a de novo mutation in the sodium channel gene SCN4A. KOREAN JOURNAL OF PEDIATRICS 2012; 54:470-2. [PMID: 22253644 PMCID: PMC3254893 DOI: 10.3345/kjp.2011.54.11.470] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Revised: 06/07/2011] [Accepted: 07/06/2011] [Indexed: 11/27/2022]
Abstract
Familial hyperkalemic periodic paralysis (HYPP) is an autosomaldominant channelopathy characterized by transient and recurrent episodes of paralysis with concomitant hyperkalemia. Mutations in the skeletal muscle voltage-gated sodium channel gene SCN4A have been reported to be responsible for this disease. Here, we report the case of a 16-year-old girl with HYPP whose mutational analysis revealed a heterozygous c.2111C>T substitution in the SCN4A gene leading to a Thr704Met mutation in the protein sequence. The parents were clinically unaffected and did not have a mutation in the SCN4A gene. A de novo SCN4A mutation for familial HYPP has not previously been reported. The patient did not respond to acetazolamide, but showed a marked improvement in paralytic symptoms upon treatment with hydrochlorothiazide. The findings in this case indicate that a de novo mutation needs to be considered when an isolated family member is found to have a HYPP phenotype.
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Affiliation(s)
- Ji-Yeon Han
- Department of Pediatrics, Konyang University College of Medicine, Daejeon, Korea
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Kim H, Hwang H, Cheong HI, Park HW. Hypokalemic periodic paralysis; two different genes responsible for similar clinical manifestations. KOREAN JOURNAL OF PEDIATRICS 2011; 54:473-6. [PMID: 22253645 PMCID: PMC3254894 DOI: 10.3345/kjp.2011.54.11.473] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/09/2011] [Revised: 04/07/2011] [Accepted: 06/25/2011] [Indexed: 11/27/2022]
Abstract
Primary hypokalemic periodic paralysis (HOKPP) is an autosomal dominant disorder manifesting as recurrent periodic flaccid paralysis and concomitant hypokalemia. HOKPP is divided into type 1 and type 2 based on the causative gene. Although 2 different ion channels have been identified as the molecular genetic cause of HOKPP, the clinical manifestations between the 2 groups are similar. We report the cases of 2 patients with HOKPP who both presented with typical clinical manifestations, but with mutations in 2 different genes (CACNA1Sp.Arg528His and SCN4A p.Arg672His). Despite the similar clinical manifestations, there were differences in the response to acetazolamide treatment between certain genotypes of SCN4A mutations and CACNA1S mutations. We identified p.Arg672His in the SCN4A gene of patient 2 immediately after the first attack through a molecular genetic testing strategy. Molecular genetic diagnosis is important for genetic counseling and selecting preventive treatment.
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Affiliation(s)
- Hunmin Kim
- Department of Pediatrics, Seoul National University Bundang Hospital, Seongnam, Korea
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Tricarico D, Camerino DC. Recent advances in the pathogenesis and drug action in periodic paralyses and related channelopathies. Front Pharmacol 2011; 2:8. [PMID: 21687503 PMCID: PMC3108473 DOI: 10.3389/fphar.2011.00008] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2011] [Accepted: 02/08/2011] [Indexed: 11/13/2022] Open
Abstract
The periodic paralysis (PP) are rare autosomal-dominant disorders associated to mutations in the skeletal muscle sodium, calcium, and potassium channel genes characterized by muscle fiber depolarization with un-excitability, episodes of weakness with variations in serum potassium concentrations. Recent advances in thyrotoxic PP and hypokalemic PP (hypoPP) confirm the involvement of the muscle potassium channels in the pathogenesis of the diseases and their role as target of action for drugs of therapeutic interest. The novelty in the gating pore currents theory help to explain the disease symptoms, and open the possibility to more specifically target the disease. It is now known that the fiber depolarization in the hypoPP is due to an unbalance between the novel identified depolarizing gating pore currents (Igp) carried by protons or Na+ ions flowing through aberrant alternative pathways of the mutant subunits and repolarizing inwardly rectifying potassium channel (Kir) currents which also includes the ATP-sensitive subtype. Abnormal activation of the Igp or deficiency in the Kir channels predispose to fiber depolarization. One pharmacological strategy is based on blocking the Igp without affecting normal channel gating. It remains safe and effective the proposal of targeting the KATP, Kir channels, or BK channels by drugs capable to specifically open at nanomolar concentrations the skeletal muscle subtypes with less side effects.
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Affiliation(s)
- Domenico Tricarico
- Department of Pharmacobiology, Faculty of Pharmacy, University of Bari Italy
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Kil TH, Kim JB. Severe respiratory phenotype caused by a de novo Arg528Gly mutation in the CACNA1S gene in a patient with hypokalemic periodic paralysis. Eur J Paediatr Neurol 2010; 14:278-81. [PMID: 19822448 DOI: 10.1016/j.ejpn.2009.08.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2009] [Revised: 08/24/2009] [Accepted: 08/31/2009] [Indexed: 10/20/2022]
Abstract
Hypokalemic periodic paralysis (HOKPP) is a rare disorder characterized by episodic muscle weakness with hypokalemia. Mutations in the CACNA1S gene, which encodes the alpha 1-subunit of the skeletal muscle L-type voltage-dependent calcium channel, have been reported to be mainly responsible for HOKPP. The paralytic attacks generally spare the respiratory muscles and the heart. Here, we report the case of a 16-year-old boy who presented with frequent respiratory insufficiency during the severe attacks. Mutational analysis revealed a heterozygous c.1582C>G substitution in the CACNA1S gene, leading to an Arg528Gly mutation in the protein sequence. The parents were clinically unaffected and did not show a mutation in the CACNA1S gene. A de novo Arg528Gly mutation has not previously been reported. The patient described here presents the unique clinical characteristics, including a severe respiratory phenotype and a reduced susceptibility to cold exposure. The patient did not respond to acetazolamide and showed a marked improvement of the paralytic symptoms on treatment with a combination of spironolactone, amiloride, and potassium supplements.
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Affiliation(s)
- Tae-Hwan Kil
- Department of Pediatrics, College of Medicine, Konyang University, 685 Gasoowon-dong, Su-goo, Daejun, Choongnam 302-718, South Korea
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Matthews E, Hanna MG. Muscle channelopathies: does the predicted channel gating pore offer new treatment insights for hypokalaemic periodic paralysis? J Physiol 2010; 588:1879-86. [PMID: 20123788 DOI: 10.1113/jphysiol.2009.186627] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Hypokalaemic periodic paralysis (hypoPP) is the archetypal skeletal muscle channelopathy caused by dysfunction of one of two sarcolemmal ion channels, either the sodium channel Nav1.4 or the calcium channel Cav1.1. Clinically, hypoPP is characterised by episodes of often severe flaccid muscle paralysis, in which the muscle fibre membrane becomes electrically inexcitable, and which may be precipitated by low serum potassium levels. Initial functional characterisation of hypoPP mutations failed to adequately explain the pathomechanism of the disease. Recently, as more pathogenic mutations involving loss of positive charge have been identified in the S4 segments of either channel, the hypothesis that an abnormal gating pore current may be important has emerged. Such an aberrant gating pore current has been identified in mutant Nav1.4 channels and has prompted potentially significant advances in this area. The carbonic anhydrase inhibitor acetazolamide has been used as a treatment for hypokalaemic periodic paralysis for over 40 years but its precise therapeutic mechanism of action is unclear. In this review we summarise the recent advances in the understanding of the molecular pathophysiology of hypoPP and consider how these may relate to the reported beneficial effects of acetazolamide. We also consider potential areas for future therapeutic development.
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Affiliation(s)
- E Matthews
- MRC Centre for Neuromuscular Disease, University College London Hospitals/University College London, UCL, Institute of Neurology, London, UK
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Kim SJ, Lee YJ, Kim JB. Reduced expression and abnormal localization of the K(ATP) channel subunit SUR2A in patients with familial hypokalemic periodic paralysis. Biochem Biophys Res Commun 2009; 391:974-8. [PMID: 19962959 DOI: 10.1016/j.bbrc.2009.11.177] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2009] [Accepted: 11/27/2009] [Indexed: 11/28/2022]
Abstract
Familial hypokalemic periodic paralysis is an autosomal-dominant channelopathy that features episodic attacks of flaccid paralysis with concomitant hypokalemia. Reduced activity of ATP-sensitive K(+) (K(ATP)) channels is suggested to be responsible for this disorder; however, the molecular mechanisms have not yet been elucidated. In this study, we investigated the molecular mechanism of reduced K(ATP) channel activity in skeletal muscle cells of patients with familial hypokalemic periodic paralysis. We examined the mRNA and protein levels of SUR2A, a K(ATP) channel subunit, in cells from patients (patient cells) and normal individuals (normal cells). Our results demonstrated that normal cells exposed to 50mM potassium buffer, which was used to induce depolarization, did not show significant change in the SUR2A mRNA levels; however, the protein level significantly increased in the cytosolic fraction. When the patient cells were exposed to 50mM potassium buffer, the SUR2A mRNA level significantly decreased. Further, the protein level of SUR2A significantly increased in the membrane fraction but decreased in the cytosolic fraction in patient cells. These findings suggest that abnormal localization of the SUR2A K(+) channel protein leads to reduced K(ATP) channel activity in familial hypokalemic periodic paralysis.
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Affiliation(s)
- Sung-Jo Kim
- Department of Biotechnology, Hoseo University, 165 Baebang-Myun, Asan, Chungnam, Republic of Korea
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Practical aspects in the management of hypokalemic periodic paralysis. J Transl Med 2008; 6:18. [PMID: 18426576 PMCID: PMC2374768 DOI: 10.1186/1479-5876-6-18] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2007] [Accepted: 04/21/2008] [Indexed: 11/26/2022] Open
Abstract
Management considerations in hypokalemic periodic paralysis include accurate diagnosis, potassium dosage for acute attacks, choice of diuretic for prophylaxis, identification of triggers, creating a safe physical environment, peri-operative measures, and issues in pregnancy. A positive genetic test in the context of symptoms is the gold standard for diagnosis. Potassium chloride is the favored potassium salt given at 0.5–1.0 mEq/kg for acute attacks. The oral route is favored, but if necessary, a mannitol solvent can be used for intravenous administration. Avoidance of or potassium prophylaxis for common triggers, such as rest after exercise, high carbohydrate meals, and sodium, can prevent attacks. Chronically, acetazolamide, dichlorphenamide, or potassium-sparing diuretics decrease attack frequency and severity but are of little value acutely. Potassium, water, and a telephone should always be at a patient's bedside, regardless of the presence of weakness. Perioperatively, the patient's clinical status should be checked frequently. Firm data on the management of periodic paralysis during pregnancy is lacking. Patient support can be found at .
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