Caster Semenya debate: Some physiology explained

25 Aug 2009 Posted by

How do you know the sex of a chromosome? Pull down its genes!

If only it were that easy…

Today, Team SA arrived back in South Africa after the World Championships in Berlin. The welcome home ceremony was really about one person – Caster Semenya, and the scenes in Johannesburg were just extra-ordinary. We have never seen such a huge reception for an athletics team (or even Olympic team). What a pity the “congratulations” was clouded in the controversy and political rhetoric that has now come to dominate the story.

I have some science to put out there, but to introduce that scientific discussion, I first want to put out some quotes from Leonard Chuene, who is the president of Athletics South Africa:

“Let me warn professors and scientists that the only scientists I believe in are the parents of this child,” Chuene said. “One scientist from a stupid university somewhere is going to erase the entire life of this girl.” The IAAF is still awaiting the results of the tests but Chuene refused to clarify what the process was or what would happen depending on the results.

“Why should we worry about other people’s tests? Chuene said. He also sent out a warning to the IAAF not to punish Semenya. “We are here and one thing they mustn’t do is suspend her.”

Honestly, I couldn’t make this up if I tried, those were his exact words. So, I think it safe to say that everything from this point onwards is not of concern to anyone in Athletics South Africa, since it involves my attempt at explaining some of the science around this matter of sex testing and why it’s so complex.

Intersex conditions and biological basics

Last week, when all this broke, I said that at some point, I’d pull together the basics of the biology of these conditions, and put it out there for you to read. I must stress that these are basics, and they don’t nearly do justice to the complexity of disorders of sexual development, or DSDs.

DSDs are the disorders that are often responsible for producing what is known as the intersex condition, a condition where a person develops ambiguous genitalia, and often, their genetic sex (determined by the chromosome) differs from their phenotypic sex (their exernal appearance and physiological functions, to be broad). In other words, if you have thought that XX = female and XY = male, you are about to have your perception challenged!

If you thought that a simple observation, and the presence of genitalia was the clincher, you’d again be wrong. Sometimes, genitalia are so ambiguous, that trained medical doctors will disagree and debate for hours over whether someone is male or female, even when that person is already a teenager. Final year medical students, when shown pictures of ambiguous genitalia, and asked to vote “male” or “female”, are often wrong! Unfortunately, then, examination of genitalia (the “pants test” or “shower check”), as advocated by the politicians, is not conclusive proof of anything!

Disorders of sexual development and intersex

Now, there are a multitude of DSDs and there is interaction, different levels, and a complex process of sexual development underlying them, and I can’t cover all that in this format.

However, I have done my best, and you can read my article at this website. It is a site called Competitor Running, and I contribute to it from time to time (not as often as I’d like). They requested this story, and I put together a very high level summary of the situation. So that article is my crack at summarizing the scientific basics of the debate.

Please note that this is NOT an attempt at diagnosis of Semenya’s case, and it does not represent my opinion on whether she has any condition of any sort. Unfortunately, the article was titled “What is Caster Semenya?”, which kind of implies an opinion is coming. That is not the case.

Rather, it is meant to inform people of the basics, and maybe the complexities, of sex testing. If you read that article, and you’re somewhat confused and bewildered at how complex it is, then you’ve started to appreciate the issue!

And, I dare say, you’ll be a step or two ahead of those in South Africa who are steadfastly refusing to let facts confuse them, or get in the way of a story.

The summary version – short, sweet and grossly oversimplified…

If you don’t have the time or energy, here is the very short, three paragraph summary, which fails miserably to answer any questions!

How do you know the sex of a chromosome? You pull down its genes! Unfortunately, this test fails on both counts – neither the genes nor the jeans hold the answer! We are all told that if you have two X-chromosomes, you’re female, and if you have an X and a Y chromosome, you’re male. Unfortunately, reality is often not so simple. In the undifferentiated foetus, there comes a point at which a “switch” must be flicked in order to switch on male sexual development. If that switch is not thrown, then the foetus will develop into a female, with ovaries and a uterus. Female is the “default” condition.

That “switch” is part of the Y-chromosome, and comprises a set of genes that is responsible for initiating male development. If it is present, testes are formed, testosterone is produced and male development occurs. However, for any number of reasons, sometimes the switch does not work. Or, it works, but there is a “short circuit” that prevents it from having its normal effect. The consequence is that even the presence of the Y-chromosome sometimes fails to turn on male development, and the foetus continues to develop as a female. The result? An XY female. Conversely, sometimes the switch is “faultily thrown” and an XX-foetus begins to develop as a male. This happens for chromosomal, gonadal and hormonal reasons. There are also other conditions which result from levels of hormone in the mother that can affect the foetus in the same way.

The end result is that ambiguous genitalia can develop, an XY can develop as a female, an XX can develop as a male, and a number of other physiological traits can be ‘mixed up’. These people are intersex, and they present the challenge with regards to sporting participation. Even once identified, there is no clear standard as to what is done with them. Some conditions, like AIS, are permitted, others evaluated. The ethical debate around this is huge, and one that I have no answers to. Only time will tell whether Semenya has any of these, or none at all. Until then, if this challenges your ‘binary’ view of sex and gender, then I guess it has made the point!

Again, for the full article, you can click here to read my piece.

Thanks!
Ross

P.S. Last word on the stories today of Semenya’s high testosterone levels

Today, some media outlets reported that Caster Semenya’s testosterone levels were three times higher than those normally expected in a urine sample. Obviously, given the context of the case, a lot of people are now saying “See, it’s proof”.

Unfortunately, it’s not that simple. It MAY turn out to be a piece of the puzzle, it MAY become significant when put in the context of all the other results, but by itself, it actually doesn’t mean too much. The main problem is that “normal” is a moving target, and there is a pretty wide range of testosterone levels in any population. So we need to understand what “normal” means – is it the typical level in the female population? Is it the highest level in the athletic population? The difference is important.

Perhaps the best way to treat this report for now is to say that the raised level is possibly a flag for something else, and further testing could establish what this is. Regardless, the position, for now, remains the same – wait on the collection of tests before drawing conclusions.

What is interesting is that this measurement was apparently obtained weeks before Berlin, and prompted the IAAF to request further testing. It was also the catalyst for them requesting that Semenya not enter the 800m event, since further testing was deemed necessary. Note that this was a request that would have been made jointly by the medical officer in charge of the testing and the IAAF, not just the IAAF. ASA refused, and the rest is, well, massive controversy.

And finally, it’s now emerged that the leak that saw this process made public came because a fax was sent to the wrong person. What a pity for such a sloppy mistake to have such repercussions, and the IAAF will hopefully take action there, because they’ve also got a great deal to answer for when it comes to the leak. Not for the process or their policy, mind you, but for this leak, which was a grave error.

This post is part of the following threads: News/Controversies, Caster Semenya – ongoing stories on this site. View the thread timelines for more context on this post.