Olympic Committee will require testing to detect the SRY gene from the Los Angeles 2028 Olympic Games
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And what is the reason for this measure?
According to , 1st woman to preside over the IOC, .
The genetic test will be required to confirm whether the athlete is truly female, that is, if she does not have the Y chromosome. This is because, in humans, sex is determined by the presence of the Y chromosome. Thus, an individual with 46,XX is considered female, while 46,XY is male.
The karyotype corresponds to an individual’s set of chromosomes, representing their genetic makeup. In a normal human karyotype, each cell analyzed must have 22 pairs of autosomal chromosomes (1 to 22).
The 22 pairs of human autosomes are non-sex chromosomes, identical in both sexes, which contain the vast majority of genes responsible for structural and metabolic characteristics of the body. In addition, there is a pair of sex chromosomes (XX or XY), totaling 23 pairs of chromosomes = 46 chromosomes.
Chromosomal syndromes
There are changes that can change the number of chromosomes. In , individuals have 3 sex chromosomes (karyotype 47,XXY). In this case, they are considered male, due to the presence of the Y chromosome.
In the case of (45,X karyotype), which only affects females, carriers have a single X chromosome.
Other examples are Swyer Syndrome (), in which individuals have XY chromosomes, with loss of function of the Y chromosome. Thus, the development of the body follows the female pattern, but they are, in general, infertile.
Genetic testing in sports
Due to these and other syndromes, it is not new that genetic tests, sex and gender issues are discussed and challenged in the sports world. We have some examples in history.
The New Zealander was the first openly transgender woman to compete in the Olympic Games, participating in the over 87 kg category of women’s weightlifting in the 2020, held in 2021. At 43 years old, she made history by competing, but was eliminated early after 3 failed attempts in the snatch.
is another example. She was the first trans athlete in the country to play in , with authorization from .
From 2028, in order to prevent athletes with a Y chromosome from participating in competitions in female categories, the IOC will require, once, the test that detects the presence of the Y chromosome. It is a simple genetic test used to identify the presence of the Y chromosome.
There are genes that are involved in sexual determination and differentiation. The SRY gene, for example, is exclusive to the Y chromosome and plays a fundamental role in the balance between testicular promoter genes, presenting strict and essential regulation. Its expression occurs already in the fetal period, around 40 days after fertilization in humans.
But, the differentiation of the gonads (testicles in men and ovaries in women) depends on a complex network of genes. “Normal” levels of expression that activate the testicular pathway simultaneously repress the ovarian pathway, or vice versa, for biological sex determination.
The exam can be carried out with any biological sample, including blood, saliva or a buccal swab for DNA extraction and subsequent analysis by . This way, only athletes with a negative result, without the presence of the SRY gene, will be able to compete in the female category.
Far beyond genes
The issue imposed by the IOC is complex and there is still no consensus in the scientific community. Thus, the Committee and many other sporting bodies are determining male/female sporting categories based on biological sex. With this, they try to guarantee equality within the female competition.
Athletic performance is a multifactorial and polygenic characteristic, modified by complex interactions between numerous genes, modulated by gene-environment interaction.
Recently, based on genetic analyzes in sports, they sought to identify markers associated with performance, resistance and power, crucial characteristics in elite athletes.
Others have also tried to assess risks of developing injuries, suggesting individualized training programs to improve performance in sport.
Genes on almost all chromosomes (sex, X and Y and ) have been identified as genetic markers related to sport. The great controversy over the genetic and/or biological advantages of athletes with a 46,XY karyotype (male biological sex) playing in female sports categories is mainly due to the fundamental role played during male puberty. In females, the amount of testosterone is almost 20 times less than in men.
Even though, currently, athletes with male biological sex (karyotype 46,XY), after hormonal suppression, do not have detectable levels of the hormone testosterone in their body, in the past, their entire bone and musculoskeletal structure benefited from the presence of testosterone. This is especially true for athletes who compete in sports that require strength and explosiveness.
What does this mean?
During puberty, testosterone promotes greater bone density, which directly impacts longer bone structures, greater wingspan, size and robustness, in addition to improving lung and heart capacity, which are essential for sports performance. Testosterone also helps in faster muscle recovery and contributes to greater strength gains.
Despite scientific advancement and knowledge, gains related to gender equity and other social issues, there is still a gap for athletes with mixed genders.
Perhaps, mixed gender/sex competitions, outside the traditional male/female division of sports categories, could emerge as an opportunity for athletes to compete. We still need to understand and move forward on these issues.
Jamila Alessandra Perini is a professor of Pharmacy and leader of the Pharmaceutical Sciences Research Laboratory at UERJ.
This text was published originally by at 10:14 am on April 1, 2026 and adapted for publication by Poder360.
