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Dyggve-Melchior-Clausen disease (DMC) is a rare skeletal disorder belonging to the group of spondyloepimetaphyseal dysplasias (see this term). To date around 100 cases have been recorded. Clinically, DMC is characterized by progressive dwarfism with short trunk, protruding sternum, microcephaly and mental retardation of varying severity. The disease is caused by mutations of the DYM gene (18q21.1). The large majority of mutations identified in the gene predict a loss of function of its product. DYM is expressed in the majority of tissue and codes for dymeclin, a protein which interacts with membranes of the Golgi apparatus, but its role within the cell is still unknown. Transmission is autosomal recessive. Diagnosis is based on radiological evidence revealing platyspondyly with double vertebral humps, epiphyseal and metaphyseal dysplasia and scalloped iliac crests. Differential diagnoses include Smith-McCort syndrome (SMC; see this term), which presents with the same clinical and radiological features as DMC but without intellectual deficiency, and Morquio disease (or mucopolysaccharidosis type 4, MPS IV; see this term), which is clinically similar but has specific radiological and enzymatic signs. Management requires both a multidisciplinary approach and a long-term follow-up as the disease is progressive. The disease often progresses towards orthopedic complications which can include lumbar lordosis, thoracic kyphosis, hip luxation, deformation of the knees and spinal cord compression secondary to instability of the atlas-axis. |