What kind of biological mechanisms lie behind the formation of the different genders? Some scientists now conclude that cells from male and female organisms differ in ways that result from chromosomes, not hormones, and believe that every organ in the body not just those related to reproduction has the capability to respond differently on the basis of sex. For example, unique or gender-specific features of human biology have been found in skin, bone, heart and brain, to name just a few. In addition, many diseases are expressed differently in men and women.

Researchers are working to identify and understand differences related to the cause, prevention, treatment and impact of diseases and conditions which primarily affect men or women, or which affect men and women differently with particular emphasis on gender and sex as key variables. Such differences can have a significant impact on the prevention, diagnosis and treatment of disease in both sexes.