Atelosteogenesis.

The name atelosteogenesis is proposed for a lethal chondrodysplasia characterized by deficient ossification of various bones, notably the humerus, femur, thoracic spine, and hand bones. Clinically, the patients have micromelic dwarfism with incurvated legs, club feet, often dislocation of the elbows, and, rarely, a cleft palate. The most characteristic radiographic signs are incomplete ossification of the vertebral bodies with coronal clefts of the lumbar and hypoplasia of the upper thoracic vertebral bodies, a distal hypoplasia and club shape of the humerus and the femur, and the lack of ossification of single phalanges and metacarpals in most patients. Histologically, there are clusters of chondrocytes surrounded by fibrous capsules and, more frequently, degeneration zones containing degenerated chondrocytes and copious amounts of metachromatic material in the epiphyses and the basal zone of the growth plate.