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(Ivanhoe Newswire) — New research reveals it may soon be possible to assign a gender to intersex people whose genital phenotypes and sex chromosomes don’t match.

For the first time, researchers from the United States and Germany have found testosterone leaves an irreversible molecular “signature” in cells. The finding, they report, offers a clearer picture of sex than does relying only on the presence of a Y chromosome.

For this research, scientists compared people with complete androgen insensitivity syndrome (CAIS) to people without CAIS. Androgen insensitivity syndrome results when a person who is genetically male is resistant to androgens (male hormones). The person is left with some or all of the physical traits of a woman, despite having the genetic makeup of a man.

Paul-Martin Holterhus, from University-Hospital Schleswig-Holstein, Kiel, Germany, was quoted as saying, “Androgens have long lasting effects during certain sensitive stages of our genital development and this is probably true for other organs”. He reports, “It is currently increasingly accepted that the brain shows sex-specific development in response to presence or absence of testosterone. This affects sex specific behavior and probably modulates gender identity.”

The researchers studied skin biopsies of external genitalia to compare the gene expression of normal males and CAIS females. Results show 440 genes differed in their level of transcription between males and females. Those activity levels form a ‘signature’ that researchers used to evaluate partial androgen insensitivity syndrome (AIS) samples. That information could soon help scientists better understand individual AIS cases.

Professor Holterhus concludes, “Since we compared XY females with the XY males, the difference can only be explained by differences in androgen action and not by differences in sex chromosomes.”

CAIS affects about one in 20,000 people.

This article was reported by Ivanhoe.com, which offers Medical Alerts by e-mail every day of the week. To subscribe, click on: http://www.ivanhoe.com/newsalert/.

SOURCE: BMC Genomics, published online Oct. 17, 2007

This entry was posted on Thursday, October 18th, 2007 at 12:10 pm and is filed under Biology / Biochemistry, Medical News, Sexual Health / STDs. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.