Congenital fibrosis of extraocular muscles (CFEOM) is a strabismus syndrome characterized by congenital inability to move the eye muscles, with or without ptosis (droopy eyelids). It is inherited in an autosomal dominant manner. The PHOX2A gene causes congenital fibrosis of the extraocular muscles 2 (CFEOM2), which differs from CFEOM1 because defects are in the superior and inferior divisions of the oculomotor nerve rather than just in the superior division as in CFEOM1. This condition is inherited in an autosomal recessive manner. This laboratory performs Sanger sequencing of PHOX2A.