Interstitial deletion of 8q. Occurrence in a patient with multiple exostoses and unusual facies.

A patient with multiple exostoses, mental retardation, and unusual facies has an interstitial deletion of the long arm of chromosome 8, or 46,XX, del (8) (pter leads to q22::q24.1 leads to qter). She has some features of the Langer-Giedion syndrome, but her facies are not characteristic and she does not have cone-shaped phalangeal epiphyses. Of the eight previous reports of partial deletion of the long arm of chromosome 8, four patients had exostoses and unusual facies, three of whom had characteristics of the Langer-Gieldion syndrome. The deleted segments in the patients with exostoses are not identical, although there are areas of deletion that are seen in more than one patient. Among the explanations of the relationship of the 8q deletions to exostoses is the presence of several loci on 8q that are involved in bone formation, the deletion of any of which may give rise to a similar skeletal defect.