Row over South African athlete highlights ambiguities of gender

By Thomas H. Maugh II
Los Angeles Times
August 21, 2009

Some have raised doubts whether Caster Semenya is a woman. But a scientist says physical features do not always match DNA or hormones. A variety of genetic and hormonal anomalies can lead to ambiguity.

Despite what one might think, it is not always easy to tell who is male and who is female.

In sporting events, officials who watch athletes produce a urine specimen usually can see immediately whether their genitals match their proclaimed sex. But that analysis can leave room for doubt, as with South African runner Caster Semenya.
The problem, said Dr. Joe Leigh Simpson, a pediatric geneticist at Florida International University, is that genetic or hormonal abnormalities can affect any organ system "and the gonads and external genitalia are not exempt from that." When such anomalies do occur, "it can produce confusion" because hormone levels and other aspects of physiology may not match appearance.

Moreover, there is "no single process" for determining sex because every case is different, he added. For years, sports authorities considered only the sex chromosomes: If they are XX, the athlete is female, XY and he is male. Technicians would swab the athlete's mouth to remove some cells, look at the sex chromosomes and make a determination.

But at the 1996 Atlanta Olympics, eight female athletes were determined to have XY chromosomes and were booted from the Games. Further studies, however, showed that they were physiologically female even though their genes said they were male, and they were reinstated.

Genes are only a blueprint, and sometimes nature doesn't follow the blueprint precisely. Take the examples of XY athletes who appear to be women. At least five enzymes are required to synthesize testosterone, the hormone that produces most male characteristics, and occasionally one of those enzymes is defective. When that happens, the genitals are typically male and tiny, the person doesn't have much body hair and he is generally feminized. By determining which testosterone precursor is present in unusually large amounts, researchers can determine which enzyme is defective. Such people are normally eligible to compete as women.

In other genetic males, the receptor that the testosterone binds to is defective and it doesn't matter how much testosterone is present. That male is classified as androgen resistant, but the results are the same: feminization. Genitalia are typically female. Often, such people are raised as females and don't find out they are genetically male until they don't get menstrual periods. They are often tall, slender and attractive, and there has been speculation that movie stars Marlene Dietrich and Greta Garbo were in this category.

Neither anomaly gives the person strength or endurance beyond that of a normal female and subjects are allowed to compete as women.

The condition of being genetically female, or XX, but appearing male can often be traced to congenital adrenal hyperplasia, in which the adrenal glands produce excess testosterone. The woman may look like a boy with tiny male genitals, but once a month will pass blood. If the condition is caught early in life, doctors usually recommend surgery to create female genitalia. But many persons with the condition live normal lives as men.

Another possibility that could account for a disconnect between genetics and appearance is mosaicism, in which the individual has more than one set of genes, in some cases, some cells could be XX and others XY. That occurs because of a faulty division at a very early stage in the embryo, or if two embryos fuse, and can produce a variety of mixed sexual signals.

The genetics community has "well-oiled machinery" to detect and deal with sexual abnormalities in newborns, Simpson said. But when it comes to adults, the process may end up being little more than a judgment call. The ultimate determinate in sporting events: Does the abnormality give an unusual benefit?