Transcription repressor. Involved in the axonal projection and proper termination of olfactory sensory neurons (OSN). Plays a role in rostro-caudal patterning of the diencephalon and in prethalamic formation. Expression is required in OSN to cell-autonomously regulate OSN axon projections. Regulates non-cell-autonomously the layer formation of the olfactory bulb development and the interneurons. May be required for correct rostral migration of the interneuron progenitors. At 8.0 dpc expressed in prospective forebrain region. At 12.5 dpc, detected in the olfactory epithelium, septum, roof of the telencephalon, amygdala, prethalamus and hypothalamus. Expression was barely detected in the vomeronasal organs at 12.5 dpc. At 15.5 dpc, detected weakly in the olfactory epithelium, amygdala and hypothalamusat 15.5 dpc. Expression was not detected in the olfactory bulb or in the ganglionic eminences, where the interneuron progenitors of the olfactory bulb are generated. Null mutants were born alive but most of them died within one day. The olfactory bulbs were smaller than those of their wild-type at 18.5 dpc and at postnatal day 1. At 14.5 dpc and 18 dpc no abnormalities in the morphology of the telencephalon or diencephalon were detected. There seems to be a redundant role for FEZF1 and FEZF2 in diencephalon development. Belongs to the krueppel C2H2-type zinc-finger protein family.