The classic clinical features of Treacher Collins Syndrome (TCS) are present at birth and can include down-slanted palpebral fissures, lower eyelid coloboma and lower eyelash anomalies, hypoplasia of the zygomatic bones and mandible, preauricular hair growth, and ear anomalies of the middle and external ear, which can lead to conductive hearing loss. Inter- and intra- familial variable expressivity has been observed. TCS can be caused by mutations in the TCOF1 gene. GeneDx conducts bi-directional sequence analysis of the entire coding region (exons 1-26) and splice sites of the TCOF1 gene. If no mutation is found by sequencing, targeted array CGH analysis with exon-level resolution (ExonArrayDx) is available to evaluate for a deletion or duplication of one or more exons in the TCOF1 gene. Mutation-specific testing in family members and prenatal diagnosis in at-risk pregnancies is available once a mutation has been identified.