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"Silent" X Not Always Mute

Bridget M. Kuehn

JAMA. 2005;293:1961-1962.

	Since this article does not have an abstract, we have provided the first 150 words of the full text and any section headings.

Two teams of researchers are providing a clearer picture of X-linked inheritance, including some surprises in their findings that may help to explain some medically important genetic differences between men and women, and even among women.

On March 17, an international team of more than 200 scientists published the results of the sequencing of 99% of the human X chromosome in Nature (Ross et al. Nature. 2005;434:325-337). A second article in the same issue reveals that many more genes than previously thought escape X inactivation and that the number of genes that escape inactivation varies from woman to woman (Carrel and Willard. Nature. 2005;434:400-404).

X MARKS THE SPOT

Long before modern genetics made it possible to trace the molecular basis of disease, physicians had noticed inheritance patterns in which males disproportionately exhibit certain diseases, such as hemophilia, that are often found in their mother’s male relatives but that are . . . [Full Text of this Article]