Myotonic dystrophy.

Myotonic dystrophy (MYD) has been localized to chromosome 19. Like other hereditary diseases with a genetic locus assigned to chromosome 19, MYD is a genetically inherited autosomal dominant disease. It is speculated that such a genetic pattern may express the characteristics of chromosome 19. We previously proposed that abnormalities of bile acid metabolism play a pathogenetic role in MYD, in which deoxycholic acid acts as a maternal factor in association with the onset of congenital MYD. Increased gamma-glutamyl-transpeptidase (gamma GTP) (probably hydrophobic deoxycholate-solubilized gamma GTP instead of hydrophilic papain-solubilized gamma GTP) in MYD may be related to the abnormalities of bile acid metabolism. Muscle wasting in MYD may be explained by these abnormalities as well. The resemblances between common metabolism of bile acids and alcohol and between common changes in MYD and alcoholic myopathy may lend support to a hypothesis that 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha, 26-tetrol dehydrogenase and 3 alpha, 7 alpha, 12 alpha-trihydroxy-5 beta-cholestan-26-al dehydrogenase activities are impaired in MYD.