Genes or loci causing the CFEOM phenotypes include KIF21A (CFEOM1) on centromeric HSA12q12 [16,17], ARIX (CFEOM2) on HSA11q.13.3-q13.4 [18], CFEOM3 on HSA16q24.2-q24.3 [19], and CFEOM3A on HSA12p11.2-q12 [20]. Here, TUBB3 is linked to congenital fibrosis of the extraocular muscles.