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defective ossification; a defect in the normal ossification of fetal cartilages.
cleidocranial dysostosis an autosomal dominant condition in which there is defective ossification of the cranial bones, complete or partial absence of the clavicles, so that the shoulders may be brought together, or nearly together, in front, and dental and vertebral anomalies. See illustration.
Cleidocranial dysostosis. From Dorland's, 2000.
craniofacial dysostosis an autosomal dominant condition marked by a pointed or conical skull, protruding wide-set eyes, strabismus, parrot-beaked nose, and hypoplastic maxilla with relative mandibular prognathism. Called also Crouzon's disease.
mandibulofacial dysostosis a hereditary disorder occurring in two different forms: the complete form is Franceschetti syndrome and the incomplete form is Treacher Collins syndrome. Persons with the condition have downslanting eyes (antimongoloid palpebral fissures); absence of all or part of the lower lid; underdeveloped cheekbones that appear depressed; a prominent nose, wide mouth, and small receding chin; underdeveloped, malformed, or prominent ears; and small tufts of hair in front of the ears. There is often, but not always, some degree of hearing loss, usually conductive.
metaphyseal dysostosis a skeletal abnormality in which the epiphyses are normal or nearly so, and the metaphyseal tissues are replaced by masses of cartilage, producing interference with endochondral bone formation and expansion and thinning of the metaphyseal cortices.
orodigitofacial dysostosis orofaciodigital syndrome.

clei·do·cra·ni·al dys·os·to·sis

, clidocranial dysostosis [MIM*119600]
a developmental disorder characterized by absence or hypoplasia of clavicles, box-shaped cranium with open sutures, frontal bossing, sutural bones, ability to oppose shoulders, and missing teeth; autosomal dominant inheritance, caused by mutation in the transcription factor gene (CBFA1) encoding core-binding factor, runt domain, alpha-subunit 1 on 6p. There is an autosomal recessive form [MIM*216330].


(krā″nē-ō-klī″dō-dĭs-ŏs-tō′sĭs) [″ + kleis, clavicle, + dys, bad, + osteon, bone, + osis, condition]
A congenital condition that involves defective ossification of the bones of the head and face and of the clavicles.