Fibrosis of Extraocular Muscles, CFEOM2

Clinical Characteristics
Ocular Features: 

This is a congenital, autosomal recessive, nonprogressive type of CFEOM which has been described in several consanguineous Middle Eastern families.  The responsible mutations are in a different gene than the one responsible for autosomal dominant CFEOM1 cases although some of the clinical features are similar.  However, in CFEOM2 the eyes are less likely to be infraducted and instead are often fixed in extreme abduction.  In addition, the phenotype is more variable with some eyes fixed in the 'neutral' position and others having more mobility than usually seen in CFEOM1 but the clinical heterogeneity is less than that seen in CFEOM3.  Ptosis is part of both phenotypes.  All patients have severe restrictions in ocular motility.  It has been suggested that CEFOM2 patients are likely to have involvement of both superior and inferior divisions of the oculomotor nerve whereas only the superior division is abnormal in CFEOM1.  Binocular vision is absent and amblyopia is common.  The pupils may be small and respond poorly to light. Refractive errors are common.

Based on visual field testing and ERG findings, it has been suggested that subnormal vision in CFEOM2 may be due to undescribed retinal dysfunction.  

Systemic Features: 

Mild facial muscle weakness may be apparent. 


This is an autosomal recessive disorder caused by homozygous mutations in the PHOX2A gene at 11q13.3-q13.4.  Another more common form of CFEOM is the autosomal dominant CFEOM1 type (135700) in which the primary fixed deviation is infraduction. The third type is CFEOM3 (600638, 609384) which is clinically more heterogeneous. 

Other nonsyndromal forms of congenital fibrosis of extraocular muscles include: CFEOM3C (609384), CFEOM5 (616219), and CFEOM with synergistic divergence (609612).  See also Tukel CFEOM syndrome (609428).

Treatment Options: 

Restoration of normal ocular motility is difficult but cosmetic improvement is possible by correcting some of the ptosis with frontalis slings.  Corneal lubrication must be maintained and amblyopia should be treated. 

Article Title: 


Khan AO, Almutlaq M, Oystreck DT, Engle EC, Abu-Amero K, Bosley T. Retinal Dysfunction in Patients with Congenital Fibrosis of the Extraocular Muscles Type 2. Ophthalmic Genet. 2014 Jun 18:1-7.

PubMedID: 24940936

Nakano M, Yamada K, Fain J, Sener EC, Selleck CJ, Awad AH, Zwaan J, Mullaney PB, Bosley TM, Engle EC. Homozygous mutations in ARIX(PHOX2A) result in congenital fibrosis of the extraocular muscles type 2. Nat Genet. 2001 Nov;29(3):315-20.

PubMedID: 11600883

Wang SM, Zwaan J, Mullaney PB, Jabak MH, Al-Awad A, Beggs AH, Engle EC. Congenital fibrosis of the extraocular muscles type 2, an inherited exotropic strabismus fixus, maps to distal 11q13. Am J Hum Genet. 1998 Aug;63(2):517-25.

PubMedID: 9683611