Non-dystrophic myotonia Chilean cohort with predominance of the SCN4A Gly1306Glu variant

Ávila-Smirnow, Daniela; Leal, Carmen Paz Vargas; Reyes, María de Los Angeles Beytía; Zepeda, Rocío Cortés; Escobar, Raúl G.; Saa, Karin Kleinsteuber; Lucero, Marcela Lagos; Benapres, María de los Angeles Avaria; Pérez, Oslando Padilla; Leturia, J.C. Casar; Sagredo, Cecilia Mellado; Sternberg, Damien

doi:10.1016/j.nmd.2020.04.006

Cited by 7 publications

(6 citation statements)

References 24 publications

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“…[1][2][3][4][5] Many studies have compared features that can distinguish sodium from chloride channel NDM; however, few have evaluated the natural history of NDM as measured by clinical outcome assessments or standard patient-reported outcomes. 4,[6][7][8][9][10][11] CLCN1 mutations result in myotonia congenita and are inherited in a dominant or recessive fashion with a more severe phenotype associated with recessive mutations. Patients are described as having a muscular appearance, classic myotonia on exam, and decreased severity of myotonia with repeated activity (ie, "warm up").…”

Section: Introductionmentioning

confidence: 99%

“…[21][22][23] While cross-sectional studies have affirmed the general differences between subtypes of NDM, few longitudinal studies have examined the consistency of these findings over time. 4,[7][8][9][10][12][13][14][15][16][17][18][19][23][24][25] Additionally, NDM patients can experience significant lifetime morbidity due to stiffness and pain related to their muscle symptoms with no clear consensus on the best instrument to measure health impacts. 9,26,27 The NIH-funded Clinical Investigation of Neurological Channelopathies (CINCH) prospectively studied a large cohort of NDM patients utilizing a common infrastructure, shared data elements, and centralized training.…”

Section: Introductionmentioning

confidence: 99%

“…They include sodium channel myotonias, paramyotonia congenita, hyperkalemic periodic paralysis, and myotonia congenita with characteristic features of myotonia without muscle wasting 1–5 . Many studies have compared features that can distinguish sodium from chloride channel NDM; however, few have evaluated the natural history of NDM as measured by clinical outcome assessments or standard patient‐reported outcomes 4,6–11 …”

Section: Introductionmentioning

confidence: 99%

“…While cross‐sectional studies have affirmed the general differences between subtypes of NDM, few longitudinal studies have examined the consistency of these findings over time 4,7–10,12–19,23–25 . Additionally, NDM patients can experience significant lifetime morbidity due to stiffness and pain related to their muscle symptoms with no clear consensus on the best instrument to measure health impacts 9,26,27 .…”

Section: Introductionmentioning

confidence: 99%

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Non‐dystrophic myotonia: 2‐year clinical and patient reported outcomes

et al. 2022

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Introduction/Aims: Consistency of differences between non-dystrophic myotonias over time measured by standardized clinical/patient-reported outcomes is lacking. Evaluation of longitudinal data could establish clinically relevant endpoints for future research. Methods: Data from prospective observational study of 95 definite/clinically suspected non-dystrophic myotonia participants (six sites in the United States, United Kingdom, and Canada) between March 2006 and March 2009 were analyzed. Outcomes included: standardized symptom interview/exam, Short Form-36, Individualized Neuromuscular Quality of Life (INQoL), electrophysiological short/prolonged exercise tests, manual muscle testing, quantitative grip strength, modified get-upand-go test. Patterns were assigned as described by Fournier et al. Comparisons were restricted to confirmed sodium channelopathies (SCN4A, baseline, year 1, year 2: n = 34, 19, 13), chloride channelopathies (CLCN1, n = 32, 26, 18), and myotonic dystrophy type 2 (DM2, n = 9, 6, 2).Results: Muscle stiffness was the most frequent symptom over time (54.7%-64.7%).Eyelid myotonia and paradoxical handgrip/eyelid myotonia were more frequent in SCN4A. Grip strength and combined manual muscle testing remained stable. Modified get-up-and-go showed less warm up in SCN4A but remained stable. Median post short exercise decrement was stable, except for SCN4A (baseline to year 2 decrement difference 16.6% [Q1, Q3: 9.5, 39.2]). Fournier patterns type 2 (CLCN1) and 1 (SCN4A) were most specific; 40.4% of participants had a change in pattern over time. INQoL showed higher impact for SCN4A and DM2 with scores stable over time.Discussion: Symptom frequency and clinical outcome assessments were stable with defined variability in myotonia measures supporting trial designs like cross over or combined n-of-1 as important for rare disorders.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Non‐dystrophic myotonia: 2‐year clinical and patient reported outcomes

et al. 2022

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“…p.Ile693Thr (c.2078T>C) [56] positive to Mg 2+ (3,600 mg) (n = 1), aggravated symptoms with hypomagnesemia and hypocalcemia [57] USE with ACZ (5 mg/kg) (n = 1) p.Leu703Pro (c. 2108T>C) [53] NR to CBZ (800 mg), positive to ACZ (250-1,000 mg)…”

Section: Randomized Clinical Trials (Class Of Evidence I)mentioning

confidence: 99%

Targeted Therapies for Skeletal Muscle Ion Channelopathies: Systematic Review and Steps Towards Precision Medicine

Desaphy

Altamura

Vicart

et al. 2021

JND

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Background: Skeletal muscle ion channelopathies include non-dystrophic myotonias (NDM), periodic paralyses (PP), congenital myasthenic syndrome, and recently identified congenital myopathies. The treatment of these diseases is mainly symptomatic, aimed at reducing muscle excitability in NDM or modifying triggers of attacks in PP. Objective: This systematic review collected the evidences regarding effects of pharmacological treatment on muscle ion channelopathies, focusing on the possible link between treatments and genetic background. Methods: We searched databases for randomized clinical trials (RCT) and other human studies reporting pharmacological treatments. Preclinical studies were considered to gain further information regarding mutation-dependent drug effects. All steps were performed by two independent investigators, while two others critically reviewed the entire process. Results: For NMD, RCT showed therapeutic benefits of mexiletine and lamotrigine, while other human studies suggest some efficacy of various sodium channel blockers and of the carbonic anhydrase inhibitor (CAI) acetazolamide. Preclinical studies suggest that mutations may alter sensitivity of the channel to sodium channel blockers in vitro, which has been translated to humans in some cases. For hyperkalemic and hypokalemic PP, RCT showed efficacy of the CAI dichlorphenamide in preventing paralysis. However, hypokalemic PP patients carrying sodium channel mutations may have fewer benefits from DCP compared to those carrying calcium channel mutations. Few data are available for treatment of congenital myopathies. Conclusions: These studies provided limited information about the response to treatments of individual mutations or groups of mutations. A major effort is needed to perform human studies for designing a mutation-driven precision medicine in muscle ion channelopathies.

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Treatment of SCN4A‐induced myotonic crisis

2021

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be comprised of different items. Although it would be theoretically possible to co-calibrate and equate the two versions, the risk remains of these FSS scores being treated as directly equivalent.Finally and given the above caveats, we propose as an alternative that existing and more contemporary PROs that measure the impact on hand use in daily activities be chosen based on the strongest evidence for content and construct validity, thus complementing the symptom severity scale. For example, in a recent trial on sensory relearning after surgery for CTS, we used three subscales of the Michigan Hand Questionnaire (MHQ) that showed statistically significant improvements in unilateral and bilateral hand activities. 7 A further advantage is that the MHQ generates separate scores for the left and right hands, which is particularly important because CTS can have a unilateral or bilateral presentation.

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Non-dystrophic myotonia Chilean cohort with predominance of the SCN4A Gly1306Glu variant

Cited by 7 publications

References 24 publications

Non‐dystrophic myotonia: 2‐year clinical and patient reported outcomes

Non‐dystrophic myotonia: 2‐year clinical and patient reported outcomes

Targeted Therapies for Skeletal Muscle Ion Channelopathies: Systematic Review and Steps Towards Precision Medicine

Treatment of SCN4A‐induced myotonic crisis

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