Pierre Robin syndrome

**Definition:** Pierre-Robin syndrome (or Pierre-Robin sequence) is characterised by triad of orofacial morphological anomalies consisting of retrognathism, glossoptosis and a posterior median velopalatal cleft. This condition is referred to as a sequence because the posterior cleft palate is a secondary defect associated with abnormal mandibular development: mandibular hypoplasia occurring early in gestation causes the tongue to be maintained high-up in the oral cavity, preventing fusion of the palatal shelves.