In our study, we found three KIF21A mutations in 16 CFEOM1 families, including c.2860C > T (p.R954W) in eight families, c.2861G > T (p.R954L) in two families, and c.2861G > A (p.R954Q) in two families. Here, KIF21A is linked to congenital fibrosis of extraocular muscles.