ZBTB4 and microcephaly: Smoc1 has been previously identified as a causative gene for human anophthalmia and microphthalmia,18–20 and zebrafish MO knockdown experiments generated a small eye phenotype but lacked a coloboma.19 Knockdown of zbtb4 in zebrafish embryos showed high embryonic mortality (90%) with surviving morphants exhibiting early developmental defects, including microcephaly, which would prevent potential identification of eye defects.21 Therefore, both genes were excluded from further analysis.