Robin sequence

Last revised by Assoc Prof Frank Gaillard on 19 Jul 2020

Robin sequence, also called Pierre Robin syndrome or Pierre Robin anamaloid, is a congenital condition characterized by facial abnormalities. Its etiology has no genetic base, but rather, is reliant on a sequence of events, one following the other.

Robin sequence is the preferred term rather than Pierre Robin syndrome, as most cases are not syndromic 4.

Robin sequence occurs in 1 in 8500 neonates 3.

May present with upper airway obstruction, sleep disturbance or apnea.

The primary defect is a retrognathic mandible which occurs at 7-11 weeks of gestation due to abnormal development of the first pharyngeal arch (see branchial apparatus). This prevents the tongue from descending which in turn prevents fusion of palatal shelves resulting in glossoptosis (retraction of tongue), high or U-shaped palate and airway obstruction. It is characterized by

Most cases tend to be sporadic.

A sagittal fetal facial profile may show severe micrognathia. Ancillary sonographic features include

Severe micrognathia may lead to

  • obstruction of fetal swallowing: may in turn cause polyhydramnios
  • airway obstruction: may, in turn, lead to postnatal hypoxia

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