congenital fibrosis of extraocular muscles type 3A
congenital fibrosis of extraocular muscles type 3AAn autosomal dominant ocular motility disorder (OMIM:600638) with variable expression, which is marked by restrictive ophthalmoplegia affecting extraocular muscles innervated by the oculomotor and/or trochlear nerves. It is clinically characterised by anchoring of the eyes in downward gaze, ptosis, and backward tilt of the head. The ocular defects can be uni- or bilateral, and the motility defects range from mild, asymptomatic restrictions of ocular movement to complete ophthalmoplegia, with eyes fixed in a hypo- and exotropic position, ptosis, refractive error, amblyopia, and compensatory head positions. The ocular phenotype may be accompanied by extraocular features, including developmental delay, corpus callosum agenesis, basal ganglia dysmorphism, facial weakness, and polyneuropathy.
Defects of TUBB3 cause congenital fibrosis of extraocular muscles type 3A.