Types of Mutations in the Dystrophin Gene

This table shows the different types of mutations (changes) that can happen in the dystrophin Glossary Link gene, and how common the different mutations are in people with DMD and BMD.

Type of Glossary Link mutation in the dystrophin gene What happens to the Glossary Link DNA? How often this causes DMD How often this causes BMD
Large deletions Pieces of DNA are lost 60-70% of cases 80-85% of cases
Large duplications Pieces of DNA are copied 10% of cases 5-10% of cases
Point mutations and other small changes There are small changes in the DNA code 15-30% of cases 10-15% of

As the table shows, most cases of DMD and BMD are caused by large deletions.  It makes sense, then, to start by testing the dystrophin gene for large deletions.  Most of the methods that find deletions also find duplications.