An autosomal dominant or X-linked osteodysplastic disorder with severe cervical involvement.

A disorder affecting bone and cartilage growth is described in a mother and her 3-year-old son. A dysplastic process involving the vertebral bodies, most pronounced in the cervical region and leading to cervical dislocation in the first of these two patients, is the most significant complication of this disorder. This entity appears unrelated to other previously described skeletal dysplasias with cervical kyphosis as a major manifestation. This disorder is most likely autosomal dominant.