49 – DTDST Dysplasia (Including AOII and Achondrogenesis IB)

Abstract Diastrophic dysplasia (DTD) is an autosomal, recessively inherited skeletal dysplasia characterized by short limbs, normal-sized skull, cleft palate in one third of patients, characteristic swelling of the pinnae cartilage, contractures of the large joints with deformities, spinal abnormalities (scoliosis, exaggerated lumbar lordosis, cervical kyphosis), and a distinct brachydactyly associated with the characteristic hitchhiker thumbs. Ultrasound findings include shortened appendicular bones, scoliosis, deviated thumbs and halluxes, and micrognathia. DTD is caused by homozygosity or compound heterozygosity for mutations in the SLC26A2 gene; other allelic and more severe disorders include achondrogenesis type IB and atelosteogenesis type II.