Background：

In vertebrates， the genes encoding the class of transcription factors called homeobox genes are found in clusters named A， B， C， and D on four separate chromosomes. Expression of these proteins is spatially and temporally regulated during embryonic development. This gene is part of the A cluster on chromosome 7 and encodes a DNA-binding transcription factor which may regulate gene expression， morphogenesis， and differentiation. The encoded protein may be involved in the placement of hindbrain segments in the proper location along the anterior-posterior axis during development. Two transcript variants encoding two different isoforms have been found for this gene， with only one of the isoforms containing the homeodomain region.