Epidemiology of myotonic dystrophy in Italy: re-apprisal after genetic diagnosis

Before the discovery of the myotonic dystrophy (DM) gene, the DM epidemiolo gical rates could not be accurately estimated. The aim of this study was to calculate the DM prevalence rates in Padova (North-East Italy) and in four provinces of North-West Tuscany (Central Italy) and, as of 30 June 1999, t o do so using molecular genetic testing. A minimum prevalence rate of 9.31 x 10(-5) inhabitants was found, consistent with epidemiological rates world wide, and more than two times as high as those of two previous studies cond ucted in the same areas during the era prior to molecular genetic testing. This study, the first in Italy since the discovery of the DM gene, underlin es the importance of direct genetic diagnosis of DM, especially in detectin g mildly affected patients, a fundamental step in correctly estimating the risk of disease transmission in affected families.