The Page group studies the genetic differences between males and females, both within and beyond the reproductive tract, and the biological and medical ramifications of these differences.  The Page group aims to understand these differences and ramifications in a broad context, through comparative biological, evolutionary, developmental, and clinically focused analyses.  The Page laboratory’s long-term effort to sequence the sex chromosomes of eight mammals and chicken has identified genes on the Y chromosome (with counterparts on the X chromosome) that are expressed throughout the body and encode regulators of chromatin modification, transcription, translation, and protein stability.  These findings have led the Page group to take a broader view of the influence of sex chromosome constitution (XX vs. XY) on genome-wide sex differences in gene expression, as well as the biological and medical ramifications of these differences, including sex biases in disease incidence and severity.  The Page group is exploring this hypothesis on several fronts using high-throughput, genome-wide gene expression, proteomic, and epigenetic profiling.  The Page group is currently developing a new methodology for producing ultra-high-quality reference sequences of the most complex genomic regions, and applying this new methodology to generate additional mammalian sex chromosome sequences.  Finally, the Page group uses the mouse as a model system to genetically dissect the development of germ cells (which give rise to egg and sperm), which is a critical juncture in mammalian development in both sexes.  These studies have important biomedical implications for studies of infertility and germ cell cancers.