Dyggve-Melchior-Clausen disease

Dyggve-Melchior-Clausen disease (DMC disease) is a rare autosomal recessive skeletal dysplasia characterized by progressive spondyloepimetaphyseal dysplasia and intellectual disability. The condition is caused by mutations in the DYM gene (also known as FLJ20116) located on chromosome 18q21.1, which encodes the dymeclin protein involved in Golgi apparatus function and endochondral bone formation. The disease was first described in 1962 by Dyggve, Melchior, and Clausen in a Greenlandic family. The disorder primarily affects the skeletal system and the central nervous system. Key skeletal features include short-trunk dwarfism, a barrel-shaped chest, microcephaly, and characteristic radiographic findings such as generalized platyspondyly with a distinctive double-humped appearance of vertebral bodies (described as a 'lace-like' pattern of the iliac crests), irregular epiphyses, and metaphyseal irregularities. Affected individuals typically present in early childhood with short stature, waddling gait, restricted joint mobility, and progressive kyphoscoliosis. Intellectual disability of varying severity is present in most cases. A variant form known as Smith-McCort dysplasia (Smith-McCort syndrome) shares the same skeletal features but without intellectual disability and can also be caused by DYM gene mutations or RABL2A mutations. There is currently no cure or specific treatment for Dyggve-Melchior-Clausen disease. Management is supportive and multidisciplinary, focusing on orthopedic interventions for skeletal complications such as spinal deformities and joint problems, physical therapy to maintain mobility, and educational support for intellectual disability. Regular monitoring by orthopedic specialists, neurologists, and developmental specialists is recommended. Surgical intervention may be necessary for progressive spinal deformity or atlantoaxial instability, which can pose a risk of spinal cord compression.

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