Myotonic dystrophy is classified as what type of genetic disorder?

Myotonic dystrophy is classified as an autosomal dominant genetic disorder. This classification indicates that only one copy of the mutated gene, inherited from an affected parent, is sufficient to express the disease. In the case of myotonic dystrophy, the genetic mutation typically involves a CTG repeat expansion in the DMPK gene on chromosome 19 for myotonic dystrophy type 1 or a CCTG repeat expansion in the CNBP gene on chromosome 3 for type 2.

Autosomal dominant disorders often exhibit a phenomenon known as anticipation, where symptoms can become more severe or appear at an earlier age as the disorder is passed through generations, which is a characteristic feature of myotonic dystrophy. The affected individuals have a 50% chance of passing the mutated gene to their offspring, which distinguishes this inheritance pattern from autosomal recessive disorders, where two copies of a mutated gene are necessary for the disease to manifest.

Understanding the inheritance pattern of myotonic dystrophy is crucial for genetic counseling, especially for planning future pregnancies and assessing risks for family members.