KIF21A and congenital fibrosis of the extraocular muscles: To date, mutations in seven genes, i.e., KIF21A (OMIM *608,283), PHOX2A (OMIM *602,753), TUBB3 (OMIM*602,661), TUBB2B (OMIM *612,850), TUBA1A (OMIM *602,529), ECEL1 (OMIM *605,896), and COL25A1 (OMIM *610,004), have been associated with CFEOM [3, 4].