Study: Sex Important in Research

N E W   Y O R K, April 24, 2001 -- Don't ignore sex.

That's what scientists are saying in a 206-page report published today by the Institute of Medicine, part of the National Academy of Sciences.

Many of the biological differences between men and women, which can play a role in human health, have not gotten the attention they deserve, they say.

They are calling for more attention to be paid to the role that sex plays in all aspects of biology, including behavior, human health and even in basic cells.

Sex Beyond Reproduction

They want to explore, for example, how, before puberty, hormone changes manifest sexual characteristics that reinforce sexual identity through adolescence and adulthood.

"Sex differences are important beyond the reproductive system," says the study's director, Theresa Wizemann of the Institute of Medicine.

The differences between males and females, the researchers say, can play a crucial role even at the molecular and cellular aspects of life.

"With all the advances in technology of genes and gene expression we now have better tools to get better understanding of the differences between the sexes," says Mary-Lou Pardue, chairwoman of the committee that issued a new report on the subject.

X and Y Chromosome Contributions

Researchers, for example, used to consider non-sex cells as essentially asexual because they had the same genetic activity derived from one of the X chromosomes, says Pardue.

Scientists used to think the Y chromosome found in all male cells of the body and one of the two X chromosomes in all women's cells were inactive, Pardue says.

But now evidence shows the Y chromosome and the apparently inactive X chromosome also play a role in the cell's life.

All cells in the body have 22 pairs of chromosome plus either two X chromosomes in female cells or an X and a Y chromosome in male cells.

Although every cell in the body has the same genetic complement, cells behave differently because during development each cell goes through a process to become the tissue it was meant to become, such as liver or kidney.

During this process some percentage of the 30,000 to 50,000 human genes in any particular cell type get turned on or off, giving the cell its unique character.

"What is the role that contributions from the Y and the other X make in cellular activity?" Pardue asks.

Differences Don't Mean Discrimination

Although disparities between the sexes have contributed in the past to discrimination, that should not stop the exploration into diversity, the scientists say.

Women will come out "on top," in some areas, and men will do so in others, they say.

Women, for example, are able to recover language ability after a left-hemisphere stroke better than men. But women are more likely to develop heart rhythm problems after taking some drugs, known as potassium channel blockers.

Females have a more aggressive immune response to infection, but are also more likely than males to develop autoimmune diseases, such as lupus.

Why these differences occur remains unknown, and hence the new study.

"Little has been done in research looking at the sexual difference at the cellular level," explains Pardue, Boris Magasanik professor in biology at the Massachusetts Institute of Technology.

The Institute of Medicine convenes committees to examine policy matters pertaining to the health of the public. The National Academy of Sciences, under the authority granted by an act of Congress in 1863, advises the government on scientific and technical matters.