X chromosome's 'extraordinary'

Some of the differences between men and women, and among women, may be explained by new research on the X chromosome, which is linked to more than 300 human diseases. It contains 1,100 genes, or about 5 percent of the human genome, along with information that may help to improve the diagnosis of a variety of illnesses, including hemophilia, blindness, autism, obesity, and leukemia. The discovery by an international consortium of scientists, which is reported in the science journal, Nature, shows that females are far more variable than previously thought and, when it comes to genes, more complex than men. Chromosomes, which are found in the nucleus of every cell, contain genes that determine the characteristics of an individual. Women have two X chromosomes, and the researchers found surprising variability in the extent to which genes on the second chromosome were active. ''The X chromosome is definitely the most extraordinary in the human genome in terms of its inheritance pattern, its unique biology . . . and in terms of its association with human disease," said Dr. Mark Ross of the Wellcome Trust Sanger Institute in Britain, which led the consortium.

REUTERS