Acts partially redundantly with other irx members in neural patterning. Required for formation of the posterior forebrain, midbrain, hindbrain, and to a lesser extent, spinal cord. Patterns the neuroectoderm in both the anterior/posterior and dorsal/ventral axes. Does not appear to play a role in pronephros kidney development. Involved in craniofacial and gonadal development (By similarity). Modulates the migration of progenitor cell populations in branchial arches and gonads by repressing CXCL12. Expressed in the neural plate in overlapping patterns with other irx members, which all share an anterior border of expression. Broadly expressed in the tailbud rhombencephalon (hindbrain). Outside the nervous system and at tailbud stages, expressed in the developing otic vesicle and branchial arches. Belongs to the TALE/IRO homeobox family.