XG is the XG blood group antigen, and is at the pseudoautosomal boundary on the short (p) arm of chromosome X. The three 5’ exons are located in the pseudoautosomal area and the remaining exons within the X-specific end. A shorted copy of XG is found on the Y chromosome at the pseudoautosomal boundary. XG is transcribed, although not expected to make a Y-chromosome specific gene product.