Markers for bone metabolism in a long-lived case of thanatophoric dysplasia

We report a male patient with type 1 thanatophoric dysplasia, now eight years old, having a mutation in the FGFR3 gene. Radiological examination at birth revealed that the ribs and the bones of the extremities were very short and vertebral bodies were greatly reduced in height with wide intervertebral spaces. The femurs were shaped like French telephone receivers. Because of respiratory insufficiency due to the narrow thorax, the patient has been intubated and supported by continuous mechanical ventilation since the day after birth. Since 5 years of age, despite sufficient caloric intake, his body weight never increased above 4700 g, body height 49.0 cm, head circumference 46.1 cm, and chest circumference 35.8 cm. Acanthosis nigricance and huge bilateral coral-like urolithiases has been present. His mental development was severely retarded but he was able to make emotional expressions. Although developments in motor functions could not be assessed, his neurodevelopmental milestones in social relationships and language perception seemed to be at the level of a 10 to 12 month old. His bone maturation was also severely retarded. All of the assays of his serum and urinary bone formation- or resorption-related substances were within normal limits for age. Therefore, bone formation as well as bone resorption activities seemed normal and not responsible for his growth retardation.