...at least 15 percent of inactivated X chromosomes in women routinely remain at least partly active, and in some women the figure can reach 25 percent. That means as many as 300 genes on women's Xs may be outperforming their counterpart genes in men.</NITF>
<NITF>That could explain some of the biological differences between the sexes, researchers said, including differences in responses to drugs and susceptibility to some diseases. And because the gene activation patterns apparently vary considerably from woman to woman, it suggests that women as a group are more variable than men.
