Leukocyte CTG repeat length correlates with severity of myotonia in myotonic dystrophy type 1
| Autor: | E. L. Logigian, R. T. Moxley, C. L. Blood, C. A. Barbieri, W. B. Martens, A. W. Wiegner, C. A. Thornton |
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| Rok vydání: | 2004 |
| Předmět: |
Adult
Male medicine.medical_specialty Stimulation Protein Serine-Threonine Kinases Severity of Illness Index Myotonic dystrophy Myotonin-Protein Kinase Predictive Value of Tests Reference Values Internal medicine Leukocytes Humans Myotonic Dystrophy Medicine Muscle Skeletal Ulnar nerve Ulnar Nerve Hand muscles Ctg repeat business.industry Electrodiagnosis Reproducibility of Results Middle Aged Hand medicine.disease Myotonia Electric Stimulation Muscle relaxation Anesthesia Cardiology Feasibility Studies Female Neurology (clinical) Trinucleotide Repeat Expansion business Tetanic stimulation Muscle Contraction |
| Zdroj: | Neurology. 62:1081-1089 |
| ISSN: | 1526-632X 0028-3878 |
| DOI: | 10.1212/01.wnl.0000118206.49652.a3 |
| Popis: | Objective: To quantitate hand muscle myotonia and to assess the relationship between CTG repeat length and myotonia in myotonic dystrophy type 1 (DM1).Methods: First dorsal interosseous twitch and tetanic contractions evoked by single and 10-Hz ulnar nerve stimulation were recorded with a force transducer in 15 patients with genetically confirmed DM1 and 15 control subjects. An automated computer program analyzed three single and three tetanic recordings per subject on 2 successive days by placing cursors along the declining (relaxation) phase of the force recordings at 90, 50, and 5% of peak force (PF) and calculating relaxation times (RT) between these points.Results: Tetanic and twitch RT was longer and PF lower in patients than subjects. RT (90 to 5%) was above the normal mean + 2.5 SD in 13 tetanic (87%) and 11 (73%) twitch patient recordings. In DM1, prolongation of RT was due mainly to delay in the terminal (50 to 5%), rather than the initial (90 to 50%) phase of relaxation, and was much greater in tetanic than single-twitch recordings. Mean test–retest variability was 19% for tetanic RT and 16% for tetanic PF. In DM1, both tetanic and twitch RT were positively correlated with leukocyte CTG repeat length.Conclusions: In DM1, myotonia of intrinsic hand muscles can be quantitated reliably by automated analysis of tetanic and twitch RT, targeting, in particular, the terminal phase of muscle relaxation after tetanic stimulation. Severity of hand muscle myotonia depends on CTG repeat length consistent with a “triplet repeat dosage” effect on chloride channel mRNA splicing and function. |
| Databáze: | OpenAIRE |
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