KIF21A and congenital fibrosis of extraocular muscles: Likewise, mutations in the microtubule growth inhibiting kinesin KIF21A contribute to congenital fibrosis of the extraocular muscles type 1 (CFEOM1; Yamada et al., 2003), due to loss of autoinhibition of the microtubule growth inhibitor KIF21A (Cheng et al., 2014).