Genetic evidence that a Y-linked gene in man is homologous to a gene on the X chromosome

Abstract

The mammalian sex chromosomes are thought to be related to each other by sharing a common origin. That is, the X and Y chromosomes originally evolved from a pair of chromosomes that only differed at the locus determining sexual differentiation1,2. For example, this evolutionary relationship is reflected during meiosis3 in chromosomal pairing between the tip of the human X chromosome short arm and the Y chromosome which presumably implies sequence homology4. However, compelling genetic evidence for functional homology between the mammalian X and Y chromosome is lacking. We describe here the localization of a gene to the tip of the short arm of the human X chromosome and evidence for a related gene on the Y chromosome.