The term "diastrophic" is Greek and means "crooked". Diastrophic dysplasia is a skeletal dysplasia typically occurring in one in 100,000 live births but is more common in Finland (one in 33,000).(1,2) The carrier rate in this population is 1–2%. (1) Diastrophic dysplasia is a member of a skeletal dysplasia family all caused by changes in the same gene. The spectrum ranges from the milder multiple epiphyseal dysplasia, to diastrophic dysplasia to the more severe atelosteogenesis, type 2 and achondrogenesis 1B. We will limit our discussion to diastrophic dysplasia only. (3)
Learn more about treatment options.
Diastrophic dysplasia is caused by mutations in the gene coding for a sulfate transporter protein. Sulfate transport is essential for typical cartilage function. This protein is called diastrophic dysplasia sulfate transporter (DTDST) and was first identified by Hastbacka and colleagues in 1994.1 The DTDST or SLC26A2 gene is located on chromosome 5 (5q31-q34). Changes in the DTDST gene cause a reduction in sulfate transported into the cells and subsequent undersulfation of cartilage. The abnormal cartilage structure is responsible for the medical issues associated with diastrophic dysplasia.3
Diastrophic dysplasia is a short-limbed form of disproportionate short stature. A person with diastrophic dysplasia may have some or many physical characteristics associated with the condition. Intelligence is typically average.3
Diastrophic dysplasia is typically recognized at birth based on physical characteristics and radiographic evaluation. Children with a milder presentation may not be diagnosed until a later age. Genetic testing can also be recommended if a skeletal dysplasia such as diastrophic dysplasia is suspected during a prenatal ultrasound. Genetic testing can be performed on fetal DNA from an amniocentesis sample.
In parents who already have children with diastrophic dysplasia, an ultrasound scan or genetic testing (using DNA from amniocentesis or chorionic villus sampling) offers the possibility of prenatal diagnosis of this condition.
Cervical kyphosis is present in 30–50% of individuals. It is due to hypoplasia of the vertebral bodies and progressive degenerative changes in the intervertebral joints. Cervical kyphosis can range from mild to severe. In children with mild cervical kyphosis, these concerns often resolve without treatment. A predisposition to spinal cord compression is seen in severe cases, and surgery may be necessary to alleviate it. If this is performed, a halo and vest device are typically used after surgery to support the neck until healing or fusion is achieved. It is important that all children with diastrophic dysplasia are monitored for cervical kyphosis.
Scoliosis is very common in diastrophic dysplasia. There appears to be several developmental patterns of scoliosis. One pattern is that of a kyphoscoliosis which develops in infancy and is rapidly progressive. A second pattern is that of a kyphoscoliosis which develops at an older age, tends to progress more slowly, and can accelerate during puberty. The third pattern is that of a kyphoscoliosis which is also later in onset, but is mild and non-progressive. Non-invasive treatments can involve bracing and serial casting. Surgical management can include growing rod systems and ultimately spinal fusion procedures.
Foot deformity in diastrophic dysplasia is quite common and is often termed “clubfoot.” The deformity, however, is quite distinct and more complex than a classic clubfoot deformity. There are differences in both the hindfoot (towards the ankle) and the forefoot (towards the toes). The hindfoot tends to have decreased range of motion and is locked into a dorsiflexed position. The forefoot is angulated towards the midline. Taken together the foot has a “serpentine” appearance.
Types of treatment for diastrophic feet are individualized and based on an individual’s unique anatomy. It is important for the foot to be regularly monitored by an experienced pediatric orthopedic surgeon so appropriate treatments can be started at the right time. Serial casting is often utilized in infancy. Surgical correction is often required to achieve a foot position where the foot and heel can simultaneously be on the floor during walking. Recurrence is common and additional surgeries may be required. Special orthotic shoes are often beneficial.8
Joint contractures, progressive subluxation of the hips and dislocation of the knees occur due to changes in the joints. If those changes interfere with walking, surgery may be recommended at the hips and/or knees to improve function. Hip or knee replacement surgery is usually necessary in early to mid-adulthood and typically has successful results. Due to underlying changes in the cartilage of patients with diastrophic dysplasia, degenerative joint disease (arthritis) is also common.9
The walls of the trachea and bronchi are stiffened by cartilage. Due to the abnormalities which exist in cartilaginous structures in individuals with diastrophic dysplasia, the airway may be affected. The walls of the airway may be weakened and could collapse under certain circumstances. These issues are going to be more commonly seen in infancy. In extreme situations, tracheostomy and ventilatory support may be necessary.
Diastrophic dysplasia requires a multidisciplinary team approach. Regular assessment by a coordinated team which includes an orthopedist, complex-care pediatrician, pulmonologist, neurosurgeon, and physical therapist will provide the most comprehensive treatment. Specialists should be monitoring for:
Nemours has a number of service regions. Selecting your region will help us show you the right contact information and the most relevant content for you.