This gene encodes a highly conserved, putative transmembrane protein. A mutation in the mouse ortholog of this gene results in homeotic, posterior-to-anterior transformations of the axial skeleton which are similar to the phenotype of mouse homeobox C8 gene mutants. This gene is proposed to function downstream of homeobox C8 to transduce extracellular patterning information during axial skeleton development. An alternatively spliced transcript variant encoding a substantially different isoform has been described, but its biological validity has not been determined.