Discovery of three related females who type XY at the amelogenin locus

Abstract

We have identified a family in which three females carry both the male and female variants of the amelogenin gene. The father of the female proband types male, as expected. The mother of the proband is deceased and cannot be tested. The sister as well as the daughter of the proband also have the amelogenin male variant. We have been unable to determine when this male variant became associated with a female X chromosome, although identification of these three females with the male variant shows its Mendelian inheritance within this family. The proband was investigated for 16 genetic markers, other than amelogenin, that are known to be Y chromosome specific. She did not have any of this male-specific DNA. The male-specific amelogenin variant from the proband was cloned and sequenced, which showed it to be identical to the published male Y chromosome sequence of the amelogenin gene. The data are novel and have implications for those performing sex determination assays using the amelogenin locus, as well as for geneticists interested in the extent of gene conversion events involving the X and Y chromosome.