Hypoplastic facial conditions
Treacher-Collins syndrome Treacher-Collins syndrome (TCS or mandibulofacial dysostosis) is associated with bilateral first and second arch abnormalities. The ‘Treacle’ gene on chromosome 5 is implicated and inheritance of the condition is autosomal dominant with variable penetrance; clinical expression is highly variable. Prenatal diagnosis by chorionic villus sampling or amniocentesis is available. Children have distinctive features with a convex shaped facial profile and look ‘fish-like’. The IQ is normal; any developmental delay present may be related in part to hearing loss.