In mammals, gonadal sex determination is the process that determines whether the embryonic gonad will develop as testis or as ovary. The long-term objective of this project is a detailed understanding of the genes involved in this binary switching system. The guiding premise of this project is that an abundance of mutations, occurring naturally in both humans and mice, provide powerful points of entry for investigating,the sex-determining mechanism. Such defects in sex-determining genes result, in both humans and in mice, in abnormal sexual differentiation and infertility. A chief goal of the present application is identification, via genetic linkage analysis in mice, of two or more autosomal genes that play critical roles in gonadal sex determination, and analysis of the structure and function of those genes in both mice and humans. Should this line of inquiry lead to the cloning of putative sex-determining genes, the functions of those genes will be tested in transgenic mice. These studies may result in highly defined mouse models of abnormal sexual development. A related goal of the present application is the characterization of human mutations that result in sex reversal. Among the humans mutations to be characterized by detailed studies at the DNA level are: 1) gross structural anomalies of the Y chromosome associated with sex reversal of XX or XY individuals, 2) Y-chromosomal point mutations resulting in ovarian development in XY individuals, and 3) autosomal or X-linked mutations resulting in sex reversal of XX or XY individuals. A third goal of the present application is identification of the biological functions of the mammalian ZFY and ZFX genes, which encode zinc-finger proteins, via manipulations of the genes in cultured cells and in transgenic mice.
