Congenital fibrosis of the extraocular muscles (CFEOM) are a group of at least eight rare genetic eye movement disorders classified clinically and genetically (CFEOM1A, CFEOM1B, CFEOM2, CFEOM3A, CFEOM3B, CFEOM3C, Tukel syndrome, and CFEOM3 with polymicrogyria). They present at birth and are characterized by congenital non-progressive opthalmoplegia, ptosis and eyes that are fixed in an abnormal position.  Fibrosis of Extraocular Muscles, Congenital, 3A (CFEOM3A) is a non-progressive, autosomal dominant disorder marked by restrictive ophthalmoplegia affecting extraocular muscles that are innervated by the oculomotor and/or trochlear nerves.  Individuals with CFEOM3A may be bilaterally or unilaterally affected, and their oculo-motility defects range from complete ophthalmoplegia to mild asymptomatic restrictions of ocular movements.  They may also have social disability, Kallmann syndrome, intellectual disability, vocal cord paralysis, and facial weakness.  Additional features may include a progressive sensorimotor axonal polyneuropathy.

Mutations in the TUBB3 gene, located on chromosome 16q24.3, have been associated with CFEOM3A.  To date, eight different heterozygous TUBB3 missense mutations have been found in patients with CFEOM3.  This gene is expressed in all post-mitotic neurons and encodes a class III beta tubulin isotype component of microtubules, which are cytoskeletal polymers that provide structure to axons and play a critical role in motor protein transport.  CFEOM-causing missense mutations often alter the binding sites of motor and microtubules associated proteins, causing an increase in microtubule stability.