What is DSD? The rare condition behind Caster Semenya’s ban from women’s events in Olympics

Two-time Olympic gold medallist Caster Semenya secured a partial victory in her long legal battle over athletics sex eligibility rules on Thursday (Jul 10), as the European Court of Human Rights (ECHR) ruled that her right to a fair hearing was violated by the Swiss Federal Supreme Court. The ECHR court declared that the Switzerland-based court failed to properly review Semenya’s appeal from 2020, where she had challenged World Athletics’ decision that restricted her from participating in women’s events of 800m unless she reduced her natural testosterone levels.

Semenya, a South African-based sprinter, was born with differences of sexual development (DSD), a condition that causes female athletes to have naturally higher levels of testosterone. These hormone levels, according to World Athletics, provide a boost, giving such athletes an 'unfair advantage.' Now, let's understand what DSD is.

What is Difference in Sexual Development (DSD)?

Males are naturally born with 'XY' chromosomes and females with 'XX' chromosomes. But in some rare occurrences, some are born with different classifications of chromosomes that don't fit the usual ones. One such condition is known as DSD (differences of sexual development), a rare biological condition where a female is born with a reproductive structure that doesn’t fit either male or female.

In Caster Semenya’s case, she was assigned female at birth and has always identified as a woman. However, it was later revealed that she has XY chromosomes, which are found in males. She also has no uterus or ovaries, but instead, internal testes, which are a result of her specific DSD condition. Internal testes are male reproductive organs that develop inside the body, which leads to naturally higher testosterone levels.

How does higher testosterone play a role?

Testosterone is a hormone that affects human muscles, stamina, and endurance. Athletes with naturally higher testosterone levels have an edge, particularly in speed- and stamina-based sports like sprinting. Due to the same reason, World Athletics introduced rules in 2019 requiring athletes to reduce their testosterone levels through medication to compete in certain female events, a decision that ended Semenya’s participation in the Olympics.

However, if higher testosterone levels are considered an unfair advantage, then factors like height and longer limbs should also fall under the same category. Since all these qualities occur naturally, it is high time the International Olympic Committee (IOC) clearly define what truly means an unfair advantage.

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