Pierre Robin sequence is caused by defect in development of which pharyngeal arch?
I
II
IV
None of the above
Robin sequence may occur independently or in association with other syndromes and malformations. Like Treacher Collins syndrome, Robin sequence alters first-arch structures, with development of the mandible most severely affected. Infants usually have a triad of micrognathia, cleft palate, and glossoptosis (posteriorly placed tongue) Ref: Langman's embryology 11th edition Chapter 16.