- Case Report
- Open Access
Bilateral Brown syndrome in one pair of dizygotic twins: a case report
© Attarzadeh et al; licensee BioMed Central Ltd. 2010
- Received: 4 December 2008
- Accepted: 2 January 2010
- Published: 2 January 2010
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.
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.
Although there are few case reports of Brown syndrome in twins, combination of these reports may elucidate the genetic basis of this disease.
- Monozygotic Twin
- Tendon Sheath
- Dizygotic Twin
- Slit Lamp Examination
- Ocular Motility
In 1950 Brown described an eye movement anomaly as the superior oblique (SO) tendon sheath syndrome . He suspected the existence of a congenitally short SO tendon sheath, which restricted passive elevation of the adducted eye . Brown syndrome is a rare ocular movement abnormality and most cases are sporadic and unilateral, but may be bilateral in 10% of cases . Familial occurrence has been reported by several authors . Also there are few case reports of Brown syndrome in twins that might be indicative of a possible autosomal dominant or recessive inheritance. Several monozygotic twins with Brown syndrome have been reported, but we found only two reports of this syndrome in dizygotic twins[4, 5]. Here we found bilateral Brown syndrome only in one pair of dizygotic twins.
Brown syndrome is caused by a mechanical restriction of the superior oblique tendon moving through the trochlea, which results in a restriction of elevation in adduction. Most cases of Brown syndrome are congenital, but it can be acquired due to either trauma or inflammation.
Reported cases of brown syndrome in twins
Magli et al
Katz et al
Finlay et al
Kim et al
Although all of the previous reports support a possible autosomal dominant or recessive inheritance with incomplete penetrance and variable expression, our case presentation like reports of Magli et al. and Caldeira strengthens the possibility of autosomal dominant with incomplete penetration or autosomal recessive transmission, because this syndrome was found only in one pair of twins and search for finding of similar disease in their siblings was negative.
Brown syndrome is a rare ocular motility abnormality and it seems if we merge these scattered case reports in twins, probable genetic basis as one of the ethiologic factors in Brown syndrome will be highlighted.
According to our search in the literature (MEDLINE from 1950 until 2008) we didnot find similar case report (bilateral Brown syndrome in one pair of dizygotic twins).
Our key words for search in MEDLINE were Brown syndrome with bilateral and twins.
Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal.
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