title: Are Duane syndrome and infantile esotropia allelic?
abstract: OBJECTIVE
  To evaluate the clinical overlap of families with Duane syndrome and infantile esotropia to determine whether the identification of genes for Duane syndrome may explain some cases of infantile esotropia.
  
  
  METHODS
  Three separate groups of patients were evaluated. 1) Families with features of infantile esotropia were identified through the Strabismus Inheritance Study Tasmania (SIST). Clinical details of participants and their families were reviewed for any cases of Duane syndrome. 2) Cases of Duane syndrome were identified through the clinical diagnostic database at the Royal Children's Hospital, Melbourne, and private ophthalmology clinics in Melbourne and Tasmania. Previous medical notes were reviewed and family history of strabismus noted. All affected individuals were invited for re-examination in cases where a positive family history of strabismus was reported; siblings, parents, and other family members, where appropriate, were invited to be examined for signs of Duane syndrome or infantile esotropia. 3) Cases of mosaic trisomy 8, which has been associated with Duane syndrome and infantile esotropia, were reviewed for signs of strabismus.
  
  
  RESULTS
  A total of 133 families from the SIST were reviewed, but no 'pure' families of Duane syndrome were identified. Two families with infantile esotropia had several members affected with Duane syndrome. Of the 40 index cases with Duane syndrome whose families agreed to be involved in the study, 21 had a family history of ocular motility disorders, but only two of these families had multiple cases of Duane syndrome. From 24 cases with mosaic trisomy 8, one individual case had Duane syndrome and another had mild congenital cataracts and infantile esotropia.
  
  
  CONCLUSIONS
  There is clinical overlap in families with Duane syndrome and infantile esotropia. We confirmed the previous association of mosaic trisomy 8 with both Duane syndrome and infantile esotropia. These data suggest that the two conditions may be allelic and may be due to a gene on chromosome 8.
authors.affiliation: CERA, University of Melbourne, Department of Ophthalmology, Royal Victorian Eye and Ear Hospital, Australia.
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Connell
authors.forename: Robin M
authors.initials: RM
authors.lastname: Wilkinson
authors.forename: Julie M
authors.initials: JM
authors.lastname: Barbour
authors.forename: Lindsey W
authors.initials: LW
authors.lastname: Scotter
authors.forename: Johan L
authors.initials: JL
authors.lastname: Poulsen
authors.forename: M Gabriella
authors.initials: MG
authors.lastname: Wirth
authors.forename: Rohan W
authors.initials: RW
authors.lastname: Essex
authors.forename: Ravi
authors.initials: R
authors.lastname: Savarirayan
authors.forename: David A
authors.initials: DA
authors.lastname: Mackey
mesh_terms: D000483:Alleles; D002648:Child; D002898:Chromosomes, Human, Pair 8 / Q000235:genetics; D004370:Duane Retraction Syndrome / Q000175:diagnosis / Q000235:genetics*; D004948:Esotropia / Q000175:diagnosis / Q000235:genetics*; D005260:Female; D006801:Humans; D008297:Male; D009030:Mosaicism; D010375:Pedigree; D014314:Trisomy