Recurrent mutation of the KIF21A gene in Japanese patients with congenital fibrosis of the extraocular muscles.
OBJECTIVE
To report recurrent mutation of the KIF21A gene in three Japanese families in which some members have congenital fibrosis of the extraocular muscles type 1 (CFEOM1), and to describe the clinical characteristics of the families.


METHODS
Standard ocular examinations were performed on 18 normal and affected members of three unrelated families. To detect mutations, we determined the DNA sequence of exons 8, 20, and 21 and the splice sites of the KIF21A gene.


RESULTS
All affected members had a heterozygous mutation of the KIF21A gene in exon 21 (R954W). Clinically, each patient had congenital bilateral ptosis, an infraducted primary position of each eye, and the inability to raise either eye above midline.


CONCLUSIONS
The KIF21A gene mutation R954W was detected in the patients with CFEOM1 screened in this study, all of whom were Japanese, reflecting similar reports from Europe, America, the Middle East, and Japan. We suggest that mutations of the KIF21A gene contribute to the development of CFEOM1 regardless of ethnicity. We also found that the delimitation of the KIF21A gene mutation site enabled us to efficiently detect the KIF21A gene mutation despite the large number of KIF21A gene exons.
Shimizu
Satoko
S
Department of Ophthalmology, Teikyo University School of Medicine, Tokyo, Japan. stkshimi@med.teikyo-u.ac.jp.
Okinaga
Akira
A
Department of Ophthalmology, Teikyo University School of Medicine, Tokyo, Japan.
Maruo
Toshio
T
Department of Ophthalmology, Teikyo University School of Medicine, Tokyo, Japan.
D000328:Adult; D000368:Aged; D002675:Child, Preschool; D004247:DNA / Q000235:genetics*; D005091:Exons; D005260:Female; D005355:Fibrosis / Q000151:congenital / Q000473:pathology; D005819:Genetic Markers; D005838:Genotype; D006801:Humans; D007223:Infant; D016547:Kinesins / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000235:genetics*; D009801:Oculomotor Muscles / Q000473:pathology*; D009886:Ophthalmoplegia / Q000151:congenital / Q000235:genetics* / Q000473:pathology; D010375:Pedigree; D016133:Polymerase Chain Reaction
D005819:Genetic Markers; C119023:KIF21A protein, human; D009419:Nerve Tissue Proteins; D004247:DNA; D016547:Kinesins