While thanatophoric dysplasia (TD) is one of the most common life-threatening forms of skeletal dysplasia, survival is sometimes possible with life-sustaining interventions. There are two distinct forms of TD, type 1 and type 2. Its incidence is approximately two to five in 100,000 births.(1)
Learn more about treatment options.
A mutation in the fibroblast growth factor receptor-3 (FGFR3) gene is responsible for causing thanatophoric dysplasia.2 Normally the FGFR3 protein functions as the "brake" for endochondral bone growth, which is the type of bone formation that occurs at the growth plates of the long bone. A change in this gene increases the ability of the FGFR3 protein to slow bone growth. This type of change associated with an increased ability is called a "gain-of-function" mutation. Changes in the FGFR3 gene cause a wide spectrum of conditions, from hypochondroplasia and achondroplasia to thanatophoric dysplasia.
Thanatophoric dysplasia (TD) is characterized by extreme short stature. At birth, children are, on average, 40 centimeters long. TD type 1 is more common and is characterized by curved long bones, especially the femur and flat vertebral bodies. A straight femur, taller vertebral bodies, and a cloverleaf skull are typical of TD type 2.
Thanatophoric dysplasia can be recognized in utero via ultrasound. Indicators include markedly short limbs and a narrow thorax. After birth, physical and radiographic examination can provide a diagnosis. Molecular testing of the FGFR-3 gene can be done to confirm the diagnosis either prenatally via an amniocentesis sample or postnatally from a blood sample.
Classically, thanatophoric dysplasia has been understood to be terminal soon after birth due to difficulty with ventilation and development of respiratory failure. However, with advances in technology, survival can be possible for some. For infants who survive the immediate perinatal period, development of critical foramen magnum stenosis is common and decompression is required for continued survival. Patients who survive the perinatal period are frequently ventilator-dependent and typically have global developmental delays.
Children with thanatophoric dysplasia usually have long-term technology dependence for respiratory support, feeding support and mobility.
Long-term survival with TD is rare. However, nine children between the ages of 5 months and 10 years have been reported. All have significant developmental delays, extreme short stature, and are ventilator-dependent.4
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.