Van Buchem syndrome is associated with sclerosteosis and SOST-associated sclerosing bone dysplasia. Both are characterized by an osteoblast hyperactivity. This causes hyperostosis of the skull, mandible, clavicle, ribs, and diaphyses of the long bones, as well as the round bones of hips and furs. Clinical manifestations occur due to progressive bone overgrowth and the associated increase in skull thickness. The hyperostosis of the skull leads to a narrowing of the foramina and thus to pinching of the facial nerve (often leading to a facial humming) and the vestibulocochlear nerve (often leading to deafness in childhood) ). Affected individuals appear healthy at birth and achieve normal body size. Distinct facial features such as asymmetric mandibular hypertrophy, frontal protrusion, and midfacial hypoplasia, if present, are seen in middle childhood. As a rule, the manifestations of Van Buchem syndrome are milder than those of sclerosis.
Neurological complications and facial changes are less common, and sclerosteolosis is characterized by the appearance of syndactyls. Inheritance is autosomal recessive. The disease is diagnosed by means of radiological procedures and molecular genetic tests.
Therapy is limited to the treatment of complications, such as surgical decompression of pinched cranial nerves.