POU4F1 is a class IV POU domain-containing transcription factor highly expressed in the developing sensory nervous system and in cells of the B- and T-lymphocytic lineages.BRN3A (POU4F1) is a class IV POU domain-containing transcription factor highly expressed in the developing sensory nervous system and in cells of the B- and T-lymphocytic lineages (Gerrero et al., 1993).[supplied by OMIM].