HYPERTROPHIC CARDIOMYOPATHY IN CONGENITAL MYOTONIC-DYSTROPHY

Involvement of the cardiac conduction system is a common clinical feat ure in myotonic dystrophy, whereas the association of primary myocardi al abnormalities has rarely been reported. A patient with a severe for m of congenital myotonic dystrophy who developed fatal left ventricula r hypertrophy at 3 months of age and died at 2 years of age is reporte d. Serial ultrasonographic studies revealed progressive left ventricul ar hypertrophy accompanied by outflow obstruction of the left ventricl e. Southern analysis for the myotonin kinase gene revealed a 5.8 kb ex pansion of CTG repeats in addition to a fragment of normal length. The degree of expansion was much greater than those of other reported pat ients with congenital myotonic dystrophy. These findings suggest that left ventricular hypertrophy represents an extreme level of myocardial damage in myotonic dystrophy and that this damage may be related to t he larger size of the CTG repeats. (C) 1998 by Elsevier Science Inc. A ll rights reserved.