How do people get myotonic dystrophy?
Myotonic dystrophy (DM) is an inherited disease where a change (called a mutation) has occurred in a gene required for normal muscle function. The mutation prevents the gene from carrying out its function properly. The change is an autosomal dominant mutation, which means one copy of the altered gene is sufficient to cause the disorder. As a result, affected individuals have a 50% chance of passing on the mutated gene to their children. A child is equally likely to have inherited the mutated gene from either parent. If both parents do not have the disease, their children cannot inherit it. The congenital form of DM1 is inherited differently from the other types of myotonic dystrophy. Children with congenital myotonic dystrophy almost always inherit the disease from an affected mother.
