The function of ENSG00000105991 (HOXA1, homeobox A1) is as follows. Sequence-specific transcription factor (By similarity). Regulates multiple developmental processes including brainstem, inner and outer ear, abducens nerve and cardiovascular development and morphogenesis as well as cognition and behavior (PubMed:16155570). Also part of a developmental regulatory system that provides cells with specific positional identities on the anterior-posterior axis. Acts on the anterior body structures. Seems to act in the maintenance and/or generation of hindbrain segments (By similarity). Activates transcription in the presence of PBX1A and PKNOX1 (By similarity). {ECO:0000250|UniProtKB:P09022, ECO:0000250|UniProtKB:Q90423, ECO:0000269|PubMed:16155570}.