OMIM ID:
Duane Retraction Syndrome 3
Alternate Names
Defective Genes
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
Inheritance
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
Autosomal dominant disorders require only one mutation for the disease to be expressed. Since an affected parent has two chromosomes, only one of which has the mutant gene, parents can expect that half (50%) of their children will receive that one and inherit the disease. It is common for individuals that inherit the mutation, however, to not have evidence of the disease (nonpenetrance).
Autosomal dominant inheritance leads to a vertical pattern of transmission