Monozygotic twins concordant for bilateral Duane's retraction syndrome

Duane's retraction syndrome applies to a wide spectrum of motility disturbances associated with retraction of the globe and narrowing of the palpebral fissure. Although many different anatomic and physiologic disturbances of the oculomotor system are implicated, the underlying cause remains obscure. Twin studies are often useful in determining the contribution of genetics or heredity to disease, but the occurrence of Duane's retraction syndrome in twins is rare. One of a pair of monozygotic twins concordant for bilateral Duane's retraction syndrome developed a 12-diopter esotropia in primary gaze but the other has not. Neither child has a head tilt and both can fix and follow with either eye.