Skeletal dysplasias, also called osteochondrodysplasias, are a diverse group of congenital disorders characterized by abnormalities in bone (osteo) and cartilage (chondro) growth, which cause defects of the head, chest, spine, and limbs. Despite their common characterization and defects, each disorder within the broader category of skeletal dysplasias has its own incidence rate, prognosis, associated diagnoses, and recurrence risk. While each individual disorder may be considered rare, as a group, skeletal dysplasias account for a significant percentage of all congenital abnormalities.
There are over 350 distinct disorders classified as skeletal dysplasias, and a large portion of those disorders can present prenatally. Skeletal dysplasias can be detected and diagnosed as early as the first trimester via ultrasound. When skeletal dysplasia is suspected, further testing such as maternal serum screening, fetal karyotype testing, a detailed anatomy ultrasound, and fetal MRI should be utilized to provide an accurate diagnosis and rule out any additional abnormalities.
Not all skeletal dysplasias are fatal; however, several of the disorders that can be diagnosed prenatally are considered fatal in the perinatal period due to respiratory complications or additional diagnoses of fatal anomalies. Fatal skeletal dysplasias include achondrogenesis, osteogenesis imperfecta type II, short-rib polydactyly syndrome, and thanatophoric dysplasia. [60]