Dyggve-Melchior-Clausen disease (DMC) is a rare, inherited disorder that affects the bones and joints. It is caused by a mutation in the DYM gene, which is responsible for the production of a protein called dystroglycan. Symptoms of DMC include skeletal abnormalities, intellectual disability, and delayed motor development. Other features may include seizures, vision and hearing problems, and heart defects. Treatment is supportive and may include physical and occupational therapy, medications, and surgery.