title: Brown syndrome in one pair of dizygotic twins: a case report.
abstract: BACKGROUND
  Brown syndrome is a rare ocular movement abnormality. This syndrome is characterized by an inability to elevate the affected eye in adduction. Most cases are sporadic but the occurrence in Monozygotic twins has suggested the possible autosomal dominant inheritance in Brown syndrome.
  
  
  METHODS
  A 4-year-old girl (one pair of dizygotic twins) was referred to our pediatric ophthalmology clinic to assess her abnormal eye movement noticed by her mother. Visual acuity of both eyes was 20/20 with Snellen chart. Ocular motility showed mild exotropia in primary position with marked divergence in upward gaze (V pattern), mild hypotropia in adduction, and limitation of elevation in adduction of both eyes (Fig. 1A). We also examined her sister, all ocular evaluations including visual acuity, slit lamp examination, funduscopy and ocular motility (Ductions & Versions) were normal without any limitation. We also review the related articles that previously have reported Brown syndrome in twins.
  
  
  CONCLUSIONS
  Although there are few case reports of Brown syndrome in twins, combination of these reports may elucidate the genetic basis of this disease.
authors.affiliation: Poostchi eye research center, shiraz university of medical sciences, shiraz, Iran.
authors.forename: Abbas
authors.initials: A
authors.lastname: Attarzadeh
authors.forename: Abbas
authors.initials: A
authors.lastname: Hoseinirad
authors.forename: Feisal
authors.initials: F
authors.lastname: Rahat