Dyggve–Melchior–Clausen Syndrome

Dyggve-Melchior-Clausen (DMC) Syndrome is a rare autosomal recessive disorder that stunts skeletal and intellectual development. Individuals with this disorder often present with a shorter stature, minimal or decreased joint mobility, deformities of the spine, and microcephaly. Individuals with this disorder exhibit varying degrees of intellectual disability, with some individuals being impacted more severely than others.

DMC syndrome originates from mutations in the DYM gene, which encodes a protein crucial for bone and cartilage development and contributes to cognitive impairments. Mutations in the RAB33B gene also contribute to DMC syndrome, though not as much as it seems to only affect skeletal development.

DMC syndrome was first observed in 1962, when three out of eight children in a family presented with symptoms. These children were the result of an incestuous relationship between their parents; their father was their mother's paternal uncle. Initially misdiagnosed as Morquio-Ullrich disease (Morquio syndrome) due to the presence of acid mucopolysaccharides in the urine, DMC syndrome was later classified as a disorder of its own.

While there is no cure for this disorder, treatments are heavily focused on the skeletal aspect, generally through orthopedic interventions and various orthopedic surgeries. Additional, long-term care such as ongoing physical therapy and social work assistance is also given to improve the affected individual's quality of life. With proper treatment and support, those with DMC syndrome are typically able to live healthily into adulthood.