Abstract
Author(s): Laigy Ann George
Myotonic Dystrophy (DystrophiaMyotonica, DM) is an inherited type of muscular dystrophy that
affects the muscles and other body systems. People who have myotonic dystrophy have muscle
wasting and weakness in their lower legs, hands, neck and face that get worse over time. Signs
and symptoms of myotonic dystrophy usually develop when a person is in his or her twenties or
thirties. The severity of myotonic dystrophy varies widely among those who have it, even among
family members. DM is a multisystem disease with major cardiac involvement. Core features of
myotonic dystrophy are myotonia, muscle weakness, cataract, and cardiac conduction
abnormalities. Classical DM (first described by Steinert (Steinert’s disease) or DM1) has been
identified as an autosomal dominant disorder associated with the presence of an abnormal
expansion of a CTG tri nucleotide repeat on chromosome 19q13.3 (the DM 1 locus). Based on
the nature of the causing mutation, DM1 belongs to “disorders of unstable repeat expansion”.
Being the first disease described with an RNA gain-of-function mutation effect, DM1 is now the
paradigm for RNA toxicity model of the disease pathogenesis, as reviewed elsewhere. Physical
therapy offers the most promise in caring for the majority of patients. This article will mainly focus
on DM1. It will provide an insight into the basic molecular biological advances together with the
clinical manifestations of the muscular dystrophies and the latest approaches to their
management and provide up-to-date information on postmortem and clinical findings and on
diagnostic and therapeutic options in patients presenting cardiac involvement.