Of note, a second substitution at this same residue in TUBB2B, TUBB2B E421K, was reported in a dominant family with CFEOM and polymicrogyria and, in yeast, the variant stabilized microtubules and reduced kinesin localization on microtubules (Cederquist et al., 2012). The gene discussed is TUBB2B; the disease is congenital fibrosis of the extraocular muscles.