Paramyotonia congenita

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Paramyotonia congenita
Other namesParamyotonia congenita of von Eulenburg or Eulenburg disease [1]
Autosomal dominant - en.svg
This condition is inherited in an autosomal dominant manner.
Specialty Neurology   OOjs UI icon edit-ltr-progressive.svg

Paramyotonia congenita (PC) is a rare congenital autosomal dominant neuromuscular disorder characterized by "paradoxical" myotonia. [2] This type of myotonia has been termed paradoxical because it becomes worse with exercise whereas classical myotonia, as seen in myotonia congenita, is alleviated by exercise. PC is also distinguished as it can be induced by cold temperatures. Although more typical of the periodic paralytic disorders, patients with PC may also have potassium-provoked paralysis. PC typically presents within the first decade of life and has 100% penetrance. Patients with this disorder commonly present with myotonia in the face or upper extremities. The lower extremities are generally less affected. While some other related disorders result in muscle atrophy, this is not normally the case with PC. This disease can also present as hyperkalemic periodic paralysis and there is debate as to whether the two disorders are actually distinct. [3]

Contents

Symptoms and signs

Patients typically complain of muscle stiffness that can continue to focal weakness. This muscle stiffness cannot be walked off, in contrast to myotonia congenita. These symptoms are increased (and sometimes induced) in cold environments. For example, some patients have reported that eating ice cream leads to a stiffening of the throat. For other patients, exercise consistently induces symptoms of myotonia or weakness. Typical presentations of this are during squatting or repetitive fist clenching. Some patients also indicate that specific foods are able to induce symptoms of paramyotonia congenita. Isolated cases have reported that carrots and watermelon are able to induce these symptoms. The canonical definition of this disorder precludes permanent weakness in the definition of this disorder. In practice, however, this has not been strictly adhered to in the literature.[ citation needed ]

Pathophysiology

Paramyotonia congenita (as well as hyperkalemic periodic paralysis and the potassium-aggravated myotonias) is caused by mutations in a sodium channel, SCN4A. The phenotype of patients with these mutations is indicated in Table 1. These mutations affect fast inactivation of the encoded sodium channel. There are also indications that some mutations lead to altered activation and deactivation. The result of these alterations in channel kinetics is that there is prolonged inward (depolarizing) current following muscle excitation. There is also the introduction of a "window current" due to changes in the voltage sensitivity of the channel’s kinetics. These lead to a general increase in cellular excitability,[ citation needed ] as shown in figure 1.

Figure 1. Theoretical simulation of a muscle membrane potential in response to 150 ms depolarizing pulse of -45 pA. (A) Normal muscle produces only a single action potential due to such stimulus. This is due to inactivation of sodium channels, preventing their further activation even during depolarization. (B) Myotonic muscle, however, is hyperexcitable and able to produce action potentials for the duration of the stimulus pulse. This model adapted from Cannon, 1993. Myotonia figure.png
Figure 1. Theoretical simulation of a muscle membrane potential in response to 150 ms depolarizing pulse of −45 pA. (A) Normal muscle produces only a single action potential due to such stimulus. This is due to inactivation of sodium channels, preventing their further activation even during depolarization. (B) Myotonic muscle, however, is hyperexcitable and able to produce action potentials for the duration of the stimulus pulse. This model adapted from Cannon, 1993.

There has been one study of a large number of patients with paramyotonia congenita. Of 26 kindreds, it found that 17 (71%) had a mutation in SCN4A while 6 (29%) had no known mutation. There is no large difference between these two groups except that patients with no known mutation have attacks precipitated less by cold but more by hunger, are much more likely to have normal muscle biopsies, and show less decreased compound muscle action potentials when compared to patients with known mutations. [5]
 

Table 1. Summary of mutations found in patients diagnosed with paramyotonia congenita and their resulting phenotypes
Mutation Region Myotonia Weakness References
Cold Exercise/
Activity 		Potassium Cold Exercise/
Activity 		Potassium
R672C D2S4  ?  ?  ?  ?  ?  ? [5]
I693T D2S4-S5 N  ?  ? Y Y Y [6]
T704M* D2S5 Y  ?  ? Y Y Y [7] , [8] , [9] , [10]
S804F** D2S6 Y Y Y  ? Y N [11]
A1152D D3S4-S5 Y  ?  ?  ?  ?  ? [12]
A1156T* D3S4-S5 Y  ?  ?  ? Y  ? [3] , [11]
V1293I D3S4 Y Y N  ?  ? N
G1306V** D3-4 Y Y Y  ?  ? Y [13] , [14]
T1313A D3-4 Y Y N Y Y N [15]
T1313M D3-4 Y Y N Y Y**** N [13] , [16]
M1360V* D4S1  ?  ?  ? Y Y  ? [17]
M1370V* D4S1 Y Y N N N Y [18]
L1433R D4S3 Y Y Y  ? Y***** N [16]
R1448C D4S4 Y Y N N Y N [6] , [10] , [19] , [20]
R1448H D4S4 Y Y Y Y Y  ? [10] , [16] , [19] , [20]
R1448P D4S4 Y Y  ? Y  ? N [21]
R1448S D4S4 Y Y N  ? Y N [22]
R1456E D4S4 Y Y N N N N [23]
V1458F*** D4S4  ?  ?  ?  ?  ?  ? [24]
F1473S*** D4S4-S5  ?  ?  ?  ?  ?  ? [24]
M1592V* D4S6 Y Y Y Y Y Y [10] , [16] , [25] , [26] , [27] , [28] , [29]
E1702K C-term  ?  ? N  ?  ? N [5]
F1795I C-term Y  ?  ?  ?  ?  ? [30]
 
*
**
***
****
*****
 
Symptoms of both PC and hyperKPP (Periodica paralytica paramyotonica)
Also diagnosed as a Potassium-aggravated myotonia
Original case reports unpublished.
When exercised in a cold environment
After muscles were cooled
This table was adapted from Vicart et al., 2005. [31] "Cold" refers to symptoms either occurring or significantly worsening with cold temperatures. Likewise, "Exercise/Activity" refers to symptom onset or severity worsening with exercise and/or more general movement like hand clenching. "Potassium" refers to ingestion of food high in potassium or other disorders which are known to increase serum potassium levels. Mutation region nomenclature is: domain number (e.g., D1) followed by segment number (e.g., S4). Thus, D2S3 indicates that the mutation is in the 3rd membrane spanning loop of the 2nd domain. Some mutations occur between segments and are denoted similarly (e.g., D4S4-S5 occurs between the 4th and 5th segments of the 4th domain). Other mutations are located between domains and are denoted DX-Y where X and Y are domain numbers. C-term refers to the carboxy-terminus.

Diagnosis

Diagnosis of paramyotonia congenita is made upon evaluation of patient symptoms and case history. Myotonia must increase with exercise or movement and usually must worsen in cold temperatures. Patients that present with permanent weakness are normally not characterized as having PC. Electromyography may be used to distinguish between paramyotonia congenita and myotonia congenita. [32] , [33] Clinicians may also attempt to provoke episodes or myotonia and weakness/paralysis in patients in order to determine whether the patient has PC, hyperkalemic periodic paralysis, or one of the potassium-aggravated myotonias. Genomic sequencing of the SCN4A gene is the definitive diagnostic determinant.[ citation needed ]

Treatment

Some patients do not require treatment to manage the symptoms of paramyotonia congenita. Others require treatment for their muscle stiffness and often find mexiletine to be helpful. Others have found acetazolamide to be helpful as well. [34] Avoidance of myotonia triggering events is also an effective method of myotonia prevention.[ citation needed ]

Epidemiology

Paramyotonia congenita is considered an extremely rare disorder, though little epidemiological work has been done. Prevalence is generally higher in European-derived populations and lower among Asians. Epidemiological estimates have been provided for the German population. There, it was estimated that the prevalence of PC is between 1:350,000 (0.00028%) and 1:180,000 (0.00056%). [20] However, the German population of patients with PC is not uniformly distributed across the country. Many individuals with PC herald from the Ravensberg area in North-West Germany, where a founder effect seems to be responsible for most cases. [20] [35] The prevalence here is estimated at 1:6000 or 0.017%.[ citation needed ]

History

Originally thought to be separate from hyperkalemic periodic paralysis and the sodium channel myotonias, there is now considerable disagreement as to whether these disorders represent separate entities or overlapping phenotypes of a complex disorder spectrum. It was once thought that paramyotonia congenita was more common in males. Observation of the most recent generation has shown this to be untrue. On average, half of children in a family inherit the disorder regardless of gender. [36]

Related Research Articles

Myotonia is a symptom of a small handful of certain neuromuscular disorders characterized by delayed relaxation of the skeletal muscles after voluntary contraction or electrical stimulation, and the muscle shows an abnormal EMG.

<span class="mw-page-title-main">Hyperkalemia</span> Excess potassium in the blood

Hyperkalemia is an elevated level of potassium (K+) in the blood. Normal potassium levels are between 3.5 and 5.0 mmol/L (3.5 and 5.0 mEq/L) with levels above 5.5 mmol/L defined as hyperkalemia. Typically hyperkalemia does not cause symptoms. Occasionally when severe it can cause palpitations, muscle pain, muscle weakness, or numbness. Hyperkalemia can cause an abnormal heart rhythm which can result in cardiac arrest and death.

Hyperkalemic periodic paralysis is an inherited autosomal dominant disorder that affects sodium channels in muscle cells and the ability to regulate potassium levels in the blood. It is characterized by muscle hyperexcitability or weakness which, exacerbated by potassium, heat or cold, can lead to uncontrolled shaking followed by paralysis. Onset usually occurs in early childhood, but it still occurs with adults.

<span class="mw-page-title-main">Andersen–Tawil syndrome</span> Rare autosomal dominant genetic disorder

Andersen–Tawil syndrome, also called Andersen syndrome and long QT syndrome 7, is a rare genetic disorder affecting several parts of the body. The three predominant features of Andersen–Tawil syndrome include disturbances of the electrical function of the heart characterised by an abnormality seen on an electrocardiogram and a tendency to abnormal heart rhythms, physical characteristics including low-set ears and a small lower jaw, and intermittent periods of muscle weakness known as hypokalaemic periodic paralysis.

<span class="mw-page-title-main">Fainting goat</span> American breed of meat goat

The myotonic goat or Tennessee fainting goat is an American breed of goat. It is characterised by myotonia congenita, a hereditary condition that may cause it to stiffen or fall over when excited or startled. It may also be known as the fainting goat, falling goat, stiff-legged goat or nervous goat, or as the Tennessee wooden-leg goat. Four goats of this type were brought to Tennessee in the 1880s.

<span class="mw-page-title-main">Channelopathy</span> Diseases caused by disturbed function of ion channel subunits or the proteins that regulate them

Channelopathies are a group of diseases caused by the dysfunction of ion channel subunits or their interacting proteins. These diseases can be inherited or acquired by other disorders, drugs, or toxins. Mutations in genes encoding ion channels, which impair channel function, are the most common cause of channelopathies. There are more than 400 genes that encode ion channels, found in all human cell types and are involved in almost all physiological processes. Each type of channel is a multimeric complex of subunits encoded by a number of genes. Depending where the mutation occurs it may affect the gating, conductance, ion selectivity, or signal transduction of the channel.

Myotonia congenita is a congenital neuromuscular channelopathy that affects skeletal muscles. It is a genetic disorder. The hallmark of the disease is the failure of initiated contraction to terminate, often referred to as delayed relaxation of the muscles (myotonia) and rigidity. Symptoms include delayed relaxation of the muscles after voluntary contraction (myotonia), and may also include stiffness, hypertrophy (enlargement), transient weakness in some forms of the disorder, severe masseter spasm, and cramping. The condition is sometimes referred to as fainting goat syndrome, as it is responsible for the eponymous 'fainting' seen in fainting goats when presented with a sudden stimulus. Of note, myotonia congenita has no association with malignant hyperthermia (MH).

<span class="mw-page-title-main">Sodium channel</span> Transmembrane protein allowing sodium ions in and out

Sodium channels are integral membrane proteins that form ion channels, conducting sodium ions (Na+) through a cell's membrane. They belong to the superfamily of cation channels.

Periodic paralysis is a group of rare genetic diseases that lead to weakness or paralysis from common triggers such as cold, heat, high carbohydrate meals, not eating, stress or excitement and physical activity of any kind. The underlying mechanism of these diseases are malfunctions in the ion channels in skeletal muscle cell membranes that allow electrically charged ions to leak in or out of the muscle cell, causing the cell to depolarize and become unable to move.

<span class="mw-page-title-main">Hypokalemic periodic paralysis</span> Medical condition

Hypokalemic periodic paralysis (hypoKPP), also known as familial hypokalemic periodic paralysis (FHPP), is a rare, autosomal dominant channelopathy characterized by muscle weakness or paralysis when there is a fall in potassium levels in the blood. In individuals with this mutation, attacks sometimes begin in adolescence and most commonly occur with individual triggers such as rest after strenuous exercise, high carbohydrate meals, meals with high sodium content, sudden changes in temperature, and even excitement, noise, flashing lights, cold temperatures and stress. Weakness may be mild and limited to certain muscle groups, or more severe full-body paralysis. During an attack, reflexes may be decreased or absent. Attacks may last for a few hours or persist for several days. Recovery is usually sudden when it occurs, due to release of potassium from swollen muscles as they recover. Some patients may fall into an abortive attack or develop chronic muscle weakness later in life.

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Na<sub>v</sub>1.4 Protein found in humans

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<span class="mw-page-title-main">Myotonic dystrophy</span> Genetic disorder that impairs muscle function

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<span class="mw-page-title-main">Potassium-aggravated myotonia</span> Medical condition

Potassium-aggravated myotonia is a rare genetic disorder that affects skeletal muscle. Beginning in childhood or adolescence, people with this condition experience bouts of sustained muscle tensing (myotonia) that prevent muscles from relaxing normally. Myotonia causes muscle stiffness, often painful, that worsens after exercise and may be aggravated by eating potassium-rich foods such as bananas and potatoes. Stiffness occurs in skeletal muscles throughout the body. Potassium-aggravated myotonia ranges in severity from mild episodes of muscle stiffness to severe, disabling disease with frequent attacks. Potassium-aggravated myotonia may, in some cases, also cause paradoxical myotonia, in which myotonia becomes more severe at the time of movement instead of after movement has ceased. Unlike some other forms of myotonia, potassium-aggravated myotonia is not associated with episodes of muscle weakness.

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<span class="mw-page-title-main">CLCN1</span> Protein-coding gene in the species Homo sapiens

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SCN1A Protein-coding gene in the species Homo sapiens

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Ca<sub>v</sub>1.1 Mammalian protein found in Homo sapiens

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Louis Ptáček is an American neurologist and professor who contributed greatly to the field of genetics and neuroscience. He was also an HHMI investigator from 1997 to 2018. His chief areas of research include the understanding of inherited Mendelian disorders and circadian rhythm genes. Currently, Ptáček is a neurology professor and a director of the Division of Neurogenetics in University of California, San Francisco, School of Medicine. His current investigations primarily focus on extensive clinical studies in families with hereditary disorders, which include identifying and characterizing the genes responsible for neurological variations.

Hyperkalemic periodic paralysis is a genetic disorder that occurs in horses. It is also known as Impressive syndrome, after an index case in a horse named Impressive. It is an inherited autosomal dominant disorder that affects sodium channels in muscle cells and the ability to regulate potassium levels in the blood. It is characterized by muscle hyperexcitability or weakness which, exacerbated by potassium, heat or cold, can lead to uncontrolled shaking followed by paralysis.

References

  1. ↑ Facts About Myopathies | MDA Publications Archived 2007-08-05 at the Wayback Machine
  2. ↑ Eulenburg A (1886). "Über eine familiäre durch 6 Generationen verfolgbare Form kongenitaler Paramyotonie". Neurol. Zentralbl. 12: 265–72.
  3. 1 2 de Silva S, Kuncl R, Griffin J, Cornblath D, Chavoustie S (1990). "Paramyotonia congenita or hyperkalemic periodic paralysis? Clinical and electrophysiological features of each entity in one family". Muscle Nerve. 13 (1): 21–6. doi:10.1002/mus.880130106. PMID   2325698. S2CID   24805255.
  4. ↑ Cannon S, Brown R, Corey D (1993). "Theoretical reconstruction of myotonia and paralysis caused by incomplete inactivation of sodium channels". Biophys J. 65 (1): 270–88. Bibcode:1993BpJ....65..270C. doi:10.1016/S0006-3495(93)81045-2. PMC   1225722 . PMID   8396455.
  5. 1 2 3 Miller T, Dias da Silva M, Miller H, Kwiecinski H, Mendell J, Tawil R, McManis P, Griggs R, Angelini C, Servidei S, Petajan J, Dalakas M, Ranum L, Fu Y, Ptácek L (2004). "Correlating phenotype and genotype in the periodic paralyses". Neurology. 63 (9): 1647–55. doi:10.1212/01.wnl.0000143383.91137.00. PMID   15534250. S2CID   36507153.
  6. 1 2 Plassart E, Eymard B, Maurs L, Hauw J, Lyon-Caen O, Fardeau M, Fontaine B (1996). "Paramyotonia congenita: genotype to phenotype correlations in two families and report of a new mutation in the sodium channel gene". J Neurol Sci. 142 (1–2): 126–33. doi:10.1016/0022-510X(96)00173-6. PMID   8902732. S2CID   8785846.
  7. ↑ Ptácek L, George A, Griggs R, Tawil R, Kallen R, Barchi R, Robertson M, Leppert M (1991). "Identification of a mutation in the gene causing hyperkalemic periodic paralysis". Cell. 67 (5): 1021–7. doi:10.1016/0092-8674(91)90374-8. PMID   1659948. S2CID   12539865.
  8. ↑ Kim J, Hahn Y, Sohn E, Lee Y, Yun J, Kim J, Chung J (2001). "Phenotypic variation of a Thr704Met mutation in skeletal sodium channel gene in a family with paralysis periodica paramyotonica". J Neurol Neurosurg Psychiatry. 70 (5): 618–23. doi:10.1136/jnnp.70.5.618. PMC   1737343 . PMID   11309455.
  9. ↑ Brancati F, Valente E, Davies N, Sarkozy A, Sweeney M, LoMonaco M, Pizzuti A, Hanna M, Dallapiccola B (2003). "Severe infantile hyperkalaemic periodic paralysis and paramyotonia congenita: broadening the clinical spectrum associated with the T704M mutation in SCN4A". J Neurol Neurosurg Psychiatry. 74 (9): 1339–41. doi:10.1136/jnnp.74.9.1339. PMC   1738672 . PMID   12933953.
  10. 1 2 3 4 Ptáĉek L, Tawil R, Griggs R, Meola G, McManis P, Barohn R, Mendell J, Harris C, Spitzer R, Santiago F (1994). "Sodium channel mutations in acetazolamide-responsive myotonia congenita, paramyotonia congenita, and hyperkalemic periodic paralysis". Neurology. 44 (8): 1500–3. doi:10.1212/wnl.44.8.1500. PMID   8058156. S2CID   28470701.
  11. 1 2 McClatchey A, McKenna-Yasek D, Cros D, Worthen H, Kuncl R, DeSilva S, Cornblath D, Gusella J, Brown R (1992). "Novel mutations in families with unusual and variable disorders of the skeletal muscle sodium channel". Nat Genet. 2 (2): 148–52. doi:10.1038/ng1092-148. PMID   1338909. S2CID   12492661.
  12. ↑ Bouhours M, Luce S, Sternberg D, Willer J, Fontaine B, Tabti N (2005). "A1152D mutation of the Na+ channel causes paramyotonia congenita and emphasizes the role of DIII/S4-S5 linker in fast inactivation". J Physiol. 565 (Pt 2): 415–27. doi:10.1113/jphysiol.2004.081018. PMC   1464511 . PMID   15790667.
  13. 1 2 McClatchey A, Van den Bergh P, Pericak-Vance M, Raskind W, Verellen C, McKenna-Yasek D, Rao K, Haines J, Bird T, Brown R (1992). "Temperature-sensitive mutations in the III-IV cytoplasmic loop region of the skeletal muscle sodium channel gene in paramyotonia congenita". Cell. 68 (4): 769–74. doi:10.1016/0092-8674(92)90151-2. PMID   1310898. S2CID   31831830.
  14. ↑ Lerche H, Heine R, Pika U, George A, Mitrovic N, Browatzki M, Weiss T, Rivet-Bastide M, Franke C, Lomonaco M (1993). "Human sodium channel myotonia: slowed channel inactivation due to substitutions for a glycine within the III-IV linker". J Physiol. 470: 13–22. doi:10.1113/jphysiol.1993.sp019843. PMC   1143902 . PMID   8308722.
  15. ↑ Bouhours M, Sternberg D, Davoine C, Ferrer X, Willer J, Fontaine B, Tabti N (2004). "Functional characterization and cold sensitivity of T1313A, a new mutation of the skeletal muscle sodium channel causing paramyotonia congenita in humans". J Physiol. 554 (Pt 3): 635–47. doi:10.1113/jphysiol.2003.053082. PMC   1664790 . PMID   14617673.
  16. 1 2 3 4 Ptacek L, Gouw L, Kwieciński H, McManis P, Mendell J, Barohn R, George A, Barchi R, Robertson M, Leppert M (1993). "Sodium channel mutations in paramyotonia congenita and hyperkalemic periodic paralysis". Ann Neurol. 33 (3): 300–7. doi:10.1002/ana.410330312. PMID   8388676. S2CID   33366273.
  17. ↑ Wagner S, Lerche H, Mitrovic N, Heine R, George A, Lehmann-Horn F (1997). "A novel sodium channel mutation causing a hyperkalemic paralytic and paramyotonic syndrome with variable clinical expressivity". Neurology. 49 (4): 1018–25. doi:10.1212/wnl.49.4.1018. PMID   9339683. S2CID   18008683.
  18. ↑ Okuda S, Kanda F, Nishimoto K, Sasaki R, Chihara K (2001). "Hyperkalemic periodic paralysis and paramyotonia congenita--a novel sodium channel mutation". J Neurol. 248 (11): 1003–4. doi:10.1007/s004150170059. PMID   11757950. S2CID   26927085.
  19. 1 2 Ptácek L, George A, Barchi R, Griggs R, Riggs J, Robertson M, Leppert M (1992). "Mutations in an S4 segment of the adult skeletal muscle sodium channel cause paramyotonia congenita". Neuron. 8 (5): 891–7. doi:10.1016/0896-6273(92)90203-P. PMID   1316765. S2CID   41160865.
  20. 1 2 3 4 Meyer-Kleine C, Otto M, Zoll B, Koch M (1994). "Molecular and genetic characterization of German families with paramyotonia congenita and demonstration of founder effect in the Ravensberg families". Hum Genet. 93 (6): 707–10. doi:10.1007/BF00201577. PMID   8005599. S2CID   39722069.
  21. ↑ Lerche H, Mitrovic N, Dubowitz V, Lehmann-Horn F (1996). "Paramyotonia congenita: the R1448P Na+ channel mutation in adult human skeletal muscle". Ann Neurol. 39 (5): 599–608. doi:10.1002/ana.410390509. PMID   8619545. S2CID   8092621.
  22. ↑ Bendahhou S, Cummins T, Kwiecinski H, Waxman S, Ptácek L (1999). "Characterization of a new sodium channel mutation at arginine 1448 associated with moderate Paramyotonia congenita in humans". J Physiol. 518 (2): 337–44. doi:10.1111/j.1469-7793.1999.0337p.x. PMC   2269438 . PMID   10381583.
  23. ↑ Sasaki R, Takano H, Kamakura K, Kaida K, Hirata A, Saito M, Tanaka H, Kuzuhara S, Tsuji S (1999). "A novel mutation in the gene for the adult skeletal muscle sodium channel alpha-subunit (SCN4A) that causes paramyotonia congenita of von Eulenburg". Arch Neurol. 56 (6): 692–6. doi: 10.1001/archneur.56.6.692 . PMID   10369308.
  24. 1 2 Lehmann-Horn F, Rüdel R, Ricker K (1993). "Non-dystrophic myotonias and periodic paralyses. A European Neuromuscular Center Workshop held 4–6 October 1992, Ulm, Germany". Neuromuscul Disord. 3 (2): 161–8. doi:10.1016/0960-8966(93)90009-9. PMID   7689382. S2CID   20892960.
  25. ↑ Lehmann-Horn F, Rüdel R, Ricker K, Lorković H, Dengler R, Hopf H (1983). "Two cases of adynamia episodica hereditaria: in vitro investigation of muscle cell membrane and contraction parameters". Muscle Nerve. 6 (2): 113–21. doi:10.1002/mus.880060206. PMID   6304507. S2CID   21594294.
  26. ↑ Fontaine B, Khurana T, Hoffman E, Bruns G, Haines J, Trofatter J, Hanson M, Rich J, McFarlane H, Yasek D (1990). "Hyperkalemic periodic paralysis and the adult muscle sodium channel alpha-subunit gene". Science. 250 (4983): 1000–2. Bibcode:1990Sci...250.1000F. doi:10.1126/science.2173143. PMID   2173143.
  27. ↑ Rojas C, Wang J, Schwartz L, Hoffman E, Powell B, Brown R (1991). "A Met-to-Val mutation in the skeletal muscle Na+ channel alpha-subunit in hyperkalaemic periodic paralysis". Nature. 354 (6352): 387–9. Bibcode:1991Natur.354..387R. doi:10.1038/354387a0. PMID   1659668. S2CID   4372717.
  28. ↑ Heine R, Pika U, Lehmann-Horn F (1993). "A novel SCN4A mutation causing myotonia aggravated by cold and potassium". Hum Mol Genet. 2 (9): 1349–53. doi:10.1093/hmg/2.9.1349. PMID   8242056.
  29. ↑ Kelly P, Yang W, Costigan D, Farrell M, Murphy S, Hardiman O (1997). "Paramyotonia congenita and hyperkalemic periodic paralysis associated with a Met 1592 Val substitution in the skeletal muscle sodium channel alpha subunit--a large kindred with a novel phenotype". Neuromuscul Disord. 7 (2): 105–11. doi:10.1016/S0960-8966(96)00429-4. PMID   9131651. S2CID   1174464.
  30. ↑ Wu F, Gordon E, Hoffman E, Cannon S (2005). "A C-terminal skeletal muscle sodium channel mutation associated with myotonia disrupts fast inactivation". J Physiol. 565 (Pt 2): 371–80. doi:10.1113/jphysiol.2005.082909. PMC   1464529 . PMID   15774523.
  31. ↑ Vicart S, Sternberg D, Fontaine B, Meola G (2005). "Human skeletal muscle sodium channelopathies". Neurol Sci. 26 (4): 194–202. doi:10.1007/s10072-005-0461-x. PMID   16193245. S2CID   27141272.
  32. ↑ Subramony S, Malhotra C, Mishra S (1983). "Distinguishing paramyotonia congenita and myotonia congenita by electromyography". Muscle Nerve. 6 (5): 374–9. doi:10.1002/mus.880060506. PMID   6888415. S2CID   20268646.
  33. ↑ Streib E; Lane, Russell J. M.; Turnbull, Douglass M.; Hudgson, Peter; Walton, John; Brumback, Roger A.; Gerst, Jeffery W.; Heckmatt, John Z.; et al. (1984). "Evoked response testing in myotonic syndromes". Muscle Nerve. 7 (7): 590–2. doi:10.1002/mus.880070709. PMID   6544373. S2CID   222015799.
  34. ↑ Taminato T, Mori-Yoshimura M, Miki J, Sasaki R, Satoh N, Oya Y, Nishino I, Takahashi Y (2020) Paramyotonia congenita with persistent distal and facial muscle weakness: A case report with literature review. J Neuromuscul Dis
  35. ↑ Becker PE, Paramyotonia congenita (Eulenberg) in Fortschritte der allgemeinen und klinischen Humangenetik. Thieme, Stuttgart (1970).
  36. ↑ Lee, GM; Kim, JB (June 2011). "Hyperkalemic periodic paralysis and paramyotonia congenita caused by a de novo mutation in the SCN4A gene". Neurology Asia. 16 (2): 163–6.

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