title: Progressive conduction disturbance in myotonic dystrophy.
abstract: Myotonic dystrophy (DM), the commonest dystrophy in adults, is an autosomal dominant disease characterized by a variety of multisystemic features. Two main genetically distinct forms of DM have been identified: type 1 (DM1), the classic form first described by Steinert, and type 2 (DM2), identified by Ricker. DM1 is caused by trinucleotide expansion of cytosine- -thymine-guanine (CTG) in the myotonic dystrophy protein kinase gene, whereas in DM2 the expansion of tetranucleotide repeats (CCTG) in the zinc finger protein 9 gene was identified. Both mutations are dynamic and are located in non-coding parts of the genes. Phenotype variability of DM1 and DM2 is caused by a molecular mechanism due to mutated RNA toxicity. DM1 is characterized by myotonia and multi-organ damage with major cardiac involvement. The disease is usually slowly progressive and life expectancy is reduced by the increased mortality associated with cardiopulmonary complications. Sudden death can occur as a consequence of cardiac-conduction abnormalities. We present the ECG of a 26 year-old male with DM1 and progressive conduction system disturbance characterized by syncopal episodes.
authors.affiliation: Unidad de Arritmias, Departamento de Cardiología, Hospital Español de Mendoza, Argentina.
authors.forename: Jorge
authors.initials: J
authors.lastname: Palazzolo
authors.forename: Emilce
authors.initials: E
authors.lastname: Trucco
authors.forename: Mauricio
authors.initials: M
authors.lastname: Arce
authors.forename: Andrés Ricardo Pérez
authors.initials: AR
authors.lastname: Riera
authors.forename: Francisco
authors.initials: F
authors.lastname: Femenía
mesh_terms: D000328:Adult; D054537:Atrioventricular Block / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology*; D018450:Disease Progression; D004562:Electrocardiography; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D008297:Male; D009223:Myotonic Dystrophy / Q000150:complications* / Q000503:physiopathology*; D013575:Syncope / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology