Congenital
fibrosis of the extraocular muscles is a class of rare genetic disorders affecting one or more of the muscles that move the
eyeballs. Individuals with congenital
fibrosis of the
extraocular muscles (CFEOM) have varying degrees of
ophthalmoplegia (an inability to move the eyes in one or more directions) and
ptosis
Ptosis (from the Greek: πτῶσις 'falling', 'a fall', 'dropped') refers to droopiness or abnormal downward displacement of a body part or organ. Particular cases include:
* Ptosis (eyelid)
* Ptosis (chin)
* Ptosis (breasts)
* Visceroptosis, ...
. The condition is present from birth, non-progressive, runs in families, and usually affects both eyes similarly. In the most common form, the
superior recti are dysfunctional and the
inferior recti, lacking proper opposition, pull the eyes down, forcing the head to be tilted upward in order to see straight ahead.
There are three types of CFEOM, numbered 1-3. CFEOM1, the most common type, is now known to be caused by one of several mutations in the
KIF21A
Kinesin-like protein KIF21A is a protein that in humans is encoded by the ''KIF21A'' gene.
KIF21A belongs to a family of plus end-directed kinesin (see MIM 600025) motor proteins. Neurons use kinesin and dynein (see MIM 600112) microtubule-depe ...
gene, while CFEOM2 is caused by mutations in the
PHOX2A gene.
[Engle, E.C., Genetic Basis of Congenital Strabismus. Arch Ophthalmol. 2007;125(2):18]
article
/ref> CFEOM3 is caused by mutations in the TUBB3 gene.[
]
References
Further reading
GeneReviews/NCBI/NIH/UW entry on Congenital Fibrosis of the Extraocular Muscles
OMIM entries on Congenital Fibrosis of the Extraocular Muscles
*
External links
{{Medical resources
, ICD10 = H49.8
, ICD9 =
, ICDO =
, OMIM = 135700
, DiseasesDB =
, MedlinePlus =
, eMedicineSubj =
, eMedicineTopic =
, MeSH =
, GeneReviewsNBK =
, GeneReviewsName =
, Orphanet = 45358
Genetic disorders with no OMIM