Congenital fibrosis of the extraocular muscles (CFEOM) is a rare syndrome characterized by congenital restrictive ophthalmoplegia.
We describe the clinical and genetic findings in a pediatric patient with CFEOM and Marcus Gunn jaw-winking phenomenon (MG).
Mutations in KIF21A have been shown to cause CFEOM1, and several authors have reported the coexistence of CFEOM1 and MG.
The aberrant innervation between developing cranial nerves suggests a role for KIF21A in axonal development.