Channelopathy
| Channelopathy | |
|---|---|
 | |
| Sodium channel, implicated in channelopathies includingBrugada syndrome,Long QT syndrome,Dravet syndrome,Paramyotonia congenita | |
| Specialty | Medical genetics,Neuromuscular medicine,Cardiology |
| Symptoms | Dependent on type. Include:Syncope,muscle weakness,seizures,breathlessness |
| Complications | Dependent on type. Include:Sudden death |
| Causes | Genetic variants |
Channelopathiesare a group of diseases caused by the dysfunction ofion channelsubunits or their interactingproteins.These diseases can beinheritedor acquired by other disorders, drugs, or toxins. Mutations ingenesencodingion channels,which impair channel function, are the most common cause of channelopathies.[1]There are more than 400 genes that encode ion channels, found in all human cell types and are involved in almost all physiological processes.[2]Each type of channel is a multimeric complex of subunits encoded by a number of genes. Depending where themutationoccurs it may affect the gating, conductance, ion selectivity, or signal transduction of the channel.
Channelopathies can be categorized based on the organ system which they are associated with. In the cardiovascular system, the electrical impulse needed for each heartbeat is made possible by theelectrochemical gradientof each heart cell. Because the heartbeat is dependent on the proper movement of ions across the surface membrane, cardiac channelopathies make up a key group of heart diseases.[3]Long QT syndrome,the most common form of cardiac channelopathy, is characterized by prolonged ventricular repolarization, predisposing to a high risk of ventricular tachyarrhythmias (e.g., torsade de pointes), syncope, and sudden cardiac death.[1]
The channelopathies of humanskeletal muscleinclude hyper- and hypokalemic (high and low potassium blood concentrations)periodic paralysis,myotonia congenitaandparamyotonia congenita.
Channelopathies affectingsynapticfunction are a type ofsynaptopathy.
Causes
[edit]Genetic type
[edit]Mutations in genes encoding ion channels, which cause defects in channel function, are the most common cause of channelopathies.[1]
Acquired type
[edit]Acquired channelopathies are caused by acquired disorders, drug use, toxins, etc.[1]
Types
[edit]The types in the following table are commonly accepted.[by whom?][citation needed]Channelopathies currently under research, likeKir4.1potassium channel inmultiple sclerosis,are not included.
| Condition | Channel type |
|---|---|
| Bartter syndrome | various, by type |
| Brugada syndrome | various, by type |
| Catecholaminergic polymorphic ventricular tachycardia(CPVT) | Ryanodine receptor |
| Congenital hyperinsulinism | Inward-rectifier potassium ion channel |
| Cystic fibrosis | Chloride channel |
| Dravet syndrome | Voltage-gated sodium channel |
| Episodic ataxia | Voltage-gated potassium channel |
| Erythromelalgia | Voltage-gated sodium channel |
| Generalized epilepsy with febrile seizures plus | Voltage-gated sodium channel |
| Familial hemiplegic migraine | various |
| Associated with one particular disabling form offibromyalgia[4] | Voltage-gated sodium channel |
| Hyperkalemic periodic paralysis | Voltage-gated sodium channel |
| Hypokalemic periodic paralysis | Voltage-gated sodium channel or voltage-dependent calcium channel (calciumopathy) |
| Lambert–Eaton myasthenic syndrome | Voltage-gated calcium channel |
| Long QT syndrome main typeRomano-Ward syndrome |
various, by type |
| Malignant hyperthermia | Ligand-gated calcium channel |
| Mucolipidosis type IV | Non-selective cation channel |
| Myotonia congenita | Voltage-dependent chloride channel |
| Neuromyelitis optica | Aquaporin-4 water channel |
| Neuromyotonia | Voltage-gated potassium channel |
| Nonsyndromic deafness | various |
| Paramyotonia congenita (aperiodic paralysis) |
Voltage-gated sodium channel |
| Polymicrogyria(brain malformation) | Voltage-gated sodium channel,SCN3A[5]ATP1A3[6] |
| Retinitis pigmentosa(some forms) | Ligand-gated non-specific ion channels |
| Short QT syndrome | various potassium channels suspected |
| Temple–Baraitser syndrome | Voltage-gated potassium channel,KCNH1[7] |
| Timothy syndrome | Voltage-dependent calcium channel |
| Tinnitus | Voltage-gated potassium channel of the KCNQ family |
| Seizure | Voltage-dependent potassium channel[8][9] |
| Zimmermann–Laband syndrome,type1 | Voltage-gated potassium channel,KCNH1 |
Ion channels versus ion pumps
[edit]Bothchannelsandpumpsare ion transporters which move ions across membranes. Channels move ions quickly, throughpassive transport,down electrical and concentration gradients (moving "downhilll" ); whereas pumps move ions slowly, throughactive transport,building-up gradients (moving "uphill" ).[10]Historically the difference between the two seemed cut and dried; however, recent research has shown that in some ion transporters, it is not always clear whether it functions as a channel or a pump.[10]
Diseases involving ion pumps can produce symptoms similar to channelopathies, as they both involve the movement of ions across membranes.Brody disease(also known as Brody myopathy) includes symptoms similar tomyotonia congenita,including muscle stiffness and cramping after initiating exercise (delayed muscle relaxation). However, it is pseudo-myotoniaas those with Brody disease have normalEMG.[11]
Due to similar symptoms, different genes for both channels and pumps can be associated with the same disease. For instance,polymicrogyriahas been associated with the channel geneSCN3A[12]and the pump geneATP1A3,[6]among other genes that are not ion transporters.[13]
See also
[edit]- Template: ATPase disorders(ion pumps)
References
[edit]- ^abcdKim JB (January 2014)."Channelopathies".Korean Journal of Pediatrics.57(1): 1–18.doi:10.3345/kjp.2014.57.1.1.PMC3935107.PMID24578711.
- ^Imbrici P, Liantonio A, Camerino GM, De Bellis M, Camerino C, Mele A, et al. (2016-05-10)."Therapeutic Approaches to Genetic Ion Channelopathies and Perspectives in Drug Discovery".Frontiers in Pharmacology.7:121.doi:10.3389/fphar.2016.00121.PMC4861771.PMID27242528.
- ^Marbán E (January 2002). "Cardiac channelopathies".Nature.415(6868): 213–218.Bibcode:2002Natur.415..213M.doi:10.1038/415213a.PMID11805845.S2CID4419017.
- ^Vargas-Alarcon G, Alvarez-Leon E, Fragoso JM, Vargas A, Martinez A, Vallejo M, Martinez-Lavin M (February 2012)."A SCN9A gene-encoded dorsal root ganglia sodium channel polymorphism associated with severe fibromyalgia".BMC Musculoskeletal Disorders.13:23.doi:10.1186/1471-2474-13-23.PMC3310736.PMID22348792.
- ^Smith RS, Kenny CJ, Ganesh V, Jang A, Borges-Monroy R, Partlow JN, et al. (September 2018)."Sodium Channel SCN3A (NaV1.3) Regulation of Human Cerebral Cortical Folding and Oral Motor Development ".Neuron.99(5): 905–913.e7.doi:10.1016/j.neuron.2018.07.052.PMC6226006.PMID30146301.
- ^abSmith RS, Florio M, Akula SK, Neil JE, Wang Y, Hill RS, et al. (June 2021)."Early role for a Na+,K+-ATPase (ATP1A3) in brain development ".Proceedings of the National Academy of Sciences of the United States of America.118(25): e2023333118.Bibcode:2021PNAS..11823333S.doi:10.1073/pnas.2023333118.PMC8237684.PMID34161264.
- ^Simons C, Rash LD, Crawford J, Ma L, Cristofori-Armstrong B, Miller D, et al. (January 2015). "Mutations in the voltage-gated potassium channel gene KCNH1 cause Temple-Baraitser syndrome and epilepsy".Nature Genetics.47(1): 73–77.doi:10.1038/ng.3153.PMID25420144.S2CID52799681.
- ^Hunter JV,Moss AJ(January 2009). "Seizures and arrhythmias: Differing phenotypes of a common channelopathy?".Neurology.72(3): 208–209.doi:10.1212/01.wnl.0000339490.98283.c5.PMID19153369.S2CID207103822.
- ^Mulley JC, Scheffer IE, Petrou S, Berkovic SF (April 2003). "Channelopathies as a genetic cause of epilepsy".Current Opinion in Neurology.16(2): 171–176.doi:10.1097/00019052-200304000-00009.PMID12644745.S2CID40441842.
- ^abGadsby, David C. (May 2009)."Ion channels versus ion pumps: the principal difference, in principle".Nature Reviews. Molecular Cell Biology.10(5): 344–352.doi:10.1038/nrm2668.ISSN1471-0080.PMC2742554.PMID19339978.
- ^Braz, Luís; Soares-Dos-Reis, Ricardo; Seabra, Mafalda; Silveira, Fernando; Guimarães, Joana (October 2019)."Brody disease: when myotonia is not myotonia".Practical Neurology.19(5): 417–419.doi:10.1136/practneurol-2019-002224.ISSN1474-7766.PMID30996034.S2CID122401141.
- ^Smith, Richard S.; Kenny, Connor J.; Ganesh, Vijay; Jang, Ahram; Borges-Monroy, Rebeca; Partlow, Jennifer N.; Hill, R. Sean; Shin, Taehwan; Chen, Allen Y.; Doan, Ryan N.; Anttonen, Anna-Kaisa; Ignatius, Jaakko; Medne, Livija; Bönnemann, Carsten G.; Hecht, Jonathan L. (2018-09-05)."Sodium channel SCN3A (NaV1.3) regulation of human cerebral cortical folding and oral motor development".Neuron.99(5): 905–913.e7.doi:10.1016/j.neuron.2018.07.052.ISSN0896-6273.PMC6226006.PMID30146301.
- ^Stutterd, Chloe A.; Leventer, Richard J. (June 2014)."Polymicrogyria: a common and heterogeneous malformation of cortical development".American Journal of Medical Genetics. Part C, Seminars in Medical Genetics.166C(2): 227–239.doi:10.1002/ajmg.c.31399.ISSN1552-4876.PMID24888723.S2CID24534275.
Bibliography
[edit]External links
[edit]VIDEOChannel Surfing in Pediatricsby Carl E. Stafstrom, M.D., at the UW-Madison Health Sciences Learning Center.
- "The Weiss Lab".The Weiss Lab is investigating the molecular and cellular mechanisms underlying human diseases caused by dysfunction of ion channels.
- The Channelopathy Foundation - Foundation for Ion Channel diseases
- Cystic Fibrosis Foundation
- Rare Diseases Clinical Research Network