MAFB

Duane Retraction Syndrome 3

Clinical Characteristics
Ocular Features: 

This type of Duane syndrome usually has limitation of both abduction and adduction.  It may be unilateral but more often is bilateral.  Attempted adduction is accompanied by globe retraction and narrowing of the lid fissure.  MRI and postmortem examination reveals absence or hypoplasia of the abducens nerve with aberrant innervation of the lateral rectus by the oculomotor nerve in some individuals with Duane retraction syndrome.  

Amblyopia is a risk.

Systemic Features: 

Sensorineural hearing loss (unilateral or bilateral) may accompany the strabismus profile as reported among 3 of 4 individuals in a single family.  CT imaging of the temporal bone in one patient revealed a cystic common-cavity anomaly.

Genetics

Type 3 Duane syndrome is an autosomal dominant condition resulting from heterozygous mutations in the MAFB gene (20q12).  Both single base pair and full gene deletions cause loss of gene function and a dominant-negative effect.

This database also contains two additional forms of  autosomal dominant isolated Duane syndrome: DURS 1 (126800) and DURS 2 (604356).

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

Extraocular muscle surgery may improve ocular motility.  Monitoring for amblyopia is important with appropriate treatment as indicated.  Assistive hearing devices may be beneficial.  

References
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