Treacher Collins syndrome—an example of a craniofacial development defect

Treacher Collins syndrome is an autosomal dominant disorder of craniofacial development the features of which include conductive hearing loss and cleft palate; diagnosis is complicated by marked variability in expression. Whilst the underlying genetic defect is unknown it is thought to be due to an abnormality of neural crest cell migration. The mutated gene has been mapped to chromosome 5q32-33.1, a high resolution genetic and radiation hybrid map surrounding the locus created, and flanking markers identified. The critical region has subsequently been cloned in yeast artificial chromosome and attempts to isolate the mutated gene are in progress.