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KIF21A gene c.2860C>T mutation in congenital fibrosis of extraocular muscles type 1 and 3.

PURPOSE
To determine, in Taiwanese patients, the genetic basis of congenital fibrosis of the extraocular muscles (CFEOM) type 1 and 3, a group of diseases characterized by congenital restrictive ophthalmoplegia affecting muscles innervated by the oculomotor nerve.


METHODS
Linkage analysis with microsatellite markers at chromosome 12q and direct sequence analysis of the KIF21A gene were performed on three families and one sporadic CFEOM case.


RESULTS
Two of the families were classified by clinical criteria as CFEOM1 and another family as CFEOM3. All three families were shown to be linked to the 12q CFEOM1 locus. Sequence analysis disclosed a heterozygous c.2860C>T mutation in the KIF21A gene in all families and in the sporadic case. Affected family members were further confirmed by a BsrDI polymorphism.


CONCLUSIONS
CFEOM is present in Chinese populations. Both CFEOM1 and CFEOM3 can be caused by the same mutation at the KIF21A gene. The occurrence of this mutation in different ethnic groups suggests a mutation hot spot.