title: Unilateral Möbius syndrome: two cases and a review of the literature.
abstract: OBJECTIVE
  The Möbius sequence is a rare condition defined by the combination of congenital non-progressive facial and abducens nerve palsies. The etiology of the sequence is still unknown, but likely encompasses a group of heterogeneous disorders involving genetic maldevelopment of the brainstem, a fetal vascular insult and/or teratogen exposure. The clinical phenotype reported has expanded over the years, and may be associated with more extensive cranial nerve and oropharyngeal involvement, as well as limb defects.
  
  
  METHODS
  We describe two cases of children presenting with unilateral Möbius syndrome associated with ipsilateral unilateral palatal weakness. Investigations failed to identified a clear underlying etiology, but both cases shared phenotypic features of other more common cranial facial disorders such as craniofacial microsomia and the velocardiofacial syndrome.
  
  
  CONCLUSIONS
  These two cases highlight the clinical heterogeneity of the Möbius sequence. Although asymmetries are not uncommon, cases with strictly unilateral features are extremely rare, and as such these may represent a distinct subgroup that may pertain to a specific etiology. Although in many cases, evidence of an intrauterine vascular insult may be identified, a contributing genetic etiology should be considered, even in cases with strictly unilateral features. As such genes expressed in the developing rhombencephalon and its vasculature represent good candidates for future investigation.
authors.affiliation: Division of Pediatric Neurology, University of Alberta, Edmonton, Alberta, Canada; Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: F D
authors.initials: FD
authors.lastname: Jacob
authors.affiliation: Department of Radiology, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: A
authors.initials: A
authors.lastname: Kanigan
authors.affiliation: Division of Pediatric Neurology, University of Alberta, Edmonton, Alberta, Canada; Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: L
authors.initials: L
authors.lastname: Richer
authors.affiliation: Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada; Divisions of Otolaryngology and Pediatric Surgery, University of Alberta, Edmonton, Alberta, Canada; Department of Surgery, University of Alberta, Edmonton, Alberta, Canada. Electronic address: hamdy.elhakim@albertahealthservices.ca.
authors.forename: H
authors.initials: H
authors.lastname: El Hakim
mesh_terms: D000015:Abnormalities, Multiple / Q000209:etiology; D002648:Child; D004062:DiGeorge Syndrome / Q000209:etiology; D006053:Goldenhar Syndrome / Q000209:etiology; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D020331:Mobius Syndrome / Q000175:diagnosis*
keywords: Cranial facial disorder; Ipsilateral palatal paralysis; Unilateral Möbius syndrome