Also known as diastrophic dysplasia or epiphyseal dysostosis, diastrophic dwarfism is another example of rhizomelic dwarfism. It is autosomal recessive in transmission. The term diastrophic characterizes the twisted scoliosis in this disease. The suspect gene is the diastrophic dysplasia sulfate transporter.
This is a rare form of rhizomelic dwarfism, and the incidence is unknown. Overall, cartilage is malformed, resulting in several characteristic radiographic abnormalities. This cartilage abnormality often leads to death from tracheomalacia. If the patient survives infancy, there is a normal lifespan. Scoliosis is not present at birth but often is progressive, especially in the early teens. Treatment of the scoliosis includes bracing and occasionally, spinal fusion. Progressive cervical kyphosis can also occur with subluxation of the cervical spine which can result in spinal cord compression.
The characteristic deformity is the "hitchhikers" thumb. At birth, the spine may only be slightly scoliotic. However, there is relentless development of a severe kyphoscoliosis of the lumbar spine. As in achondroplasia, a broad pelvis is encountered with narrowed interpediculate distances in the spine. 25 - 50 % of patients have a cleft palate. Due to inflammation, the ear enlarges, resulting in a "cauliflower" deformity.
REFERENCES
Baitner AC, Maurer SG, Gruen MB, Di Cesare PE. The genetic basis of the osteochondrodysplasias. J Pediatr Orthop. 2000 Sep-Oct;20(5):594-605.
Stanescu V, Stanescu R, Maroteaux P. Pathogenic mechanisms in osteochondrodysplasias. J Bone Joint Surg Am. 1984 Jul;66(6):817-36.
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