RAX and Anophthalmia: Homozygous null mutations of the Rx gene in mice result in anophthalmia, with no eye development after the optic vesicle stage.13 The region also lacks other EFTFs such as Pax6 and Six3, indicating that Rx may also play a role in inducing these genes.14 A similar anophthalmia phenotype was observed in loss of function experiments on Xenopus embryos using morpholino oligonucleotides against the Xenopus homolog to Rx.15