THE HUMAN FXY GENE IS LOCATED WITHIN XP22.3 - IMPLICATIONS FOR EVOLUTION OF THE MAMMALIAN X-CHROMOSOME

It has been proposed that the pseudoautosomal region of mammals has ev olved by sequential addition of autosomal material onto the X and Y ch romosomes followed by movement of the pseudoautosomal boundary to crea te X-unique regions, We have previously described a gene, Fxy,that spa ns the pseudoautosomal boundary in mice such that the first three exon s of the gene are located on the X chromosome, but the remainder of th e gene is located on both X and Y chromosomes, Therefore, this gene mi ght be in a state of transition between pseudoautosomal and X-unique l ocations, In support of this theory we show here that the human FXY ge ne is located in Xp22.3 in humans, proximal to the pseudoautosomal bou ndary.