Wednesday, May 30, 2007

Sex in humans: It's a delicate balance.

For years we have been taught that during human development the default sex was female and an individual with a copy of the SRY gene would develop into a male. There is an interesting interview with Eric Vilain from the University of California in this month's Scientific American. Dr. Vilain's work has updated this simplistic notion and his work has implications that go beyond genetics.

Dr. Vilain studies intersex individuals. He got interested in this topic as a medical student in Paris. He was assigned to the pediatrics unit and was shocked at how doctors made decisions about gender assignment for children with ambiguous genitalia.

His lab has discovered that sex and perhaps gender seem to involve a balancing act between different sets of genes. On the one hand is the SRY gene. Balancing that appear to be a series of what he calls "anti male genes", for instance the WNT4 gene that he calls female specific. Indeed this gene appears to inhibit male hormone production by females. WNT4 and other sorts of genes may also prove to be not just "anti-male" but be required for proper ovarian development, but this still needs to be demonstrated.

Vilain's work has implications for the politics and handling of gender related issues. From the transgender perspective this work is interesting because it provides an approach that might help explain gender identity 'disorders' at least in some situations. After all the SRY gene appears to be expressed in the brain. Might the same hold true for some of these other genes related to gonadal development? Might gender identity and behavior be as much about genetics as about social construction?

Indeed in another interview Dr. Vilain has this to say about gender identity:


"This is really the big enigma and to me it's also the most important aspect of
sex determination to understand because I believe out of all the definitions of
sex, gender is the most important. In fact it's how people feel that is
important, regardless of what they look like, of what their levels of hormones
are, or what their face or genitalia look like. It's what they feel within
themselves."



For the intersex community, his work has led to proposals to replace much of the nomenclature related to intersex individuals. In Vilain's view, the term 'intersex' is too vague and he would replace it with the term 'disorders of sexual development (DSD)'. Some in the intersex community support these sorts of changes because it would enable them to get medical treatment. Others think that the new nomeclature pathologizes what they view as 'normal variants.' Vilain responds:

"We can play with words like that, but for practical purposes these "normal
variants" have a lot of health risks that require lots of visits to the doctor
for a bunch of issues that intersex patients have: fertility issues, cancer
issues (the testis inside the body can increase the risk of cancer), sexual
health issues. So if you're to start going to the doctor a lot for your
condition, you can call it a normal variant, but that's not really useful.
You're calling it a normal variant for political purposes."


Yet the intersex community is not abandoning the term intersex, but using it in the sense of an idenity rahter than a set of medical conditions. Sherri Morris makes this point quite clear in the ISNA blog:


"It would be a mistake to advocate that “intersex” be replaced with “DSD” within
such community, in the same way that people with a variety of different
conditions identify themselves using terms which may vary from the terms
employed by their health care providers. For example, instead of using a
diagnosis such as “achondroplasia,” many individuals with such conditions have
banded together using the term “Little People” because it reflects their
history, culture, and real-life experience."

So we see how genetics research affects more than just medical knowledge; it affects how we view ourselves at some very fundamental levels. For the subtle conflict and balance among the genes in the human organism is reflected in the complex nuances involved in even the most basic aspects of our identity, laying waste to the simplistic notions of male and female clung to by so many in our society.

Other Links:

Brian K. Jordan, Jennifer H.-C. Shen,Robert Olaso, Holly A. Ingraham, and Eric Vilain Proc Natl Acad Sci U S A. 2003 September 16; 100(19): 10866–10871.

Intersex Society of North America

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