OTX2 and microphthalmia: Loss of murine Otx2 function due to a homozygous genetic mutation is associated with embryonic lethality due to complete loss of the forebrain, whilst heterozygous Otx2 mutant mice manifest a variable phenotype ranging from no obvious craniofacial anomaly to having microphthalmia/anophthalmia, otocephaly/micrognathia, and even acephaly in extreme cases (7, 8, 9).