What an SRY gene test can and cannot establish about an athlete

The International Olympic Committee announced on 26 March 2026 that eligibility for female-category events at the Olympic Games will be limited to athletes who return a negative result on a one-time screen for the SRY gene, with the policy applying from the 2028 Summer Games in Los Angeles [s1]. The screen can be run on saliva, a cheek swab, or a blood sample [s1][s2]. The IOC's own framing is that "the presence of the SRY gene is fixed throughout life and represents highly accurate evidence that an athlete has experienced male sex development" [s2]. IOC President Kirsty Coventry said the decision rested on safety and fairness, adding: "it is absolutely clear that it would not be fair for biological males to compete in the female category" [s2].

The policy is the largest application yet of a testing approach that a governing body had already adopted. World Athletics introduced a once-in-a-lifetime SRY test for female-category athletes with effect from 1 September 2025, first applied at the World Athletics Championships that began on 13 September 2025 [s3]. World Athletics President Sebastian Coe described the standard plainly: "We are saying, at elite level, for you to compete in the female category, you have to be biologically female" [s3]. Ahead of those championships Coe said uptake was "around about 90 per cent, probably slightly more now", with the federation contributing roughly $100 per test and offering testing at holding camps in Japan for athletes whose national federations could not provide it [s4].

What the test measures

SRY — sex determining region Y — is a segment of DNA almost always found on the Y chromosome, and it initiates the developmental cascade that produces testes [s1]. A screen for it is cheap, fast and, as a detection assay, reliable. World Athletics describes it as "a reliable proxy for determining biological sex" [s3].

The scientific objection is not that the assay fails to find the gene. It is that finding the gene answers a question about presence, not about function or outcome.

Andrew Sinclair, deputy director of the Murdoch Children's Research Institute in Melbourne and one of the researchers who identified SRY in 1990, said after the IOC announcement that the policy "is based on the overly simplistic idea that the presence of the SRY gene alone is equivalent to being male" [s5]. His specific technical point is about what a positive result leaves unresolved: it "does not tell you how SRY is functioning, whether a testis has formed, whether testosterone is produced and, if so, whether it can be used by the body" [s5]. Sinclair's framing is that male development involves multiple genes and hormone pathways beyond SRY [s5].

Both the IOC and World Athletics acknowledge part of this. Athletes who screen positive but have complete androgen insensitivity syndrome (CAIS) — a condition in which the androgen receptor does not respond to testosterone — remain eligible under the IOC policy, as do those with other differences in sex development where testosterone has no performance-enhancing effect [s1][s2]. That carve-out is itself an admission that a positive SRY result does not, on its own, establish the biological trait the policy is trying to regulate. It also shifts the burden: an athlete who screens positive must then produce medical evidence of her condition to remain eligible [s6].

The evidence gap on performance

In March 2026, 34 academics from disciplines including medicine, law, history and ethics published an editorial in the British Journal of Sports Medicine arguing the regulations are unscientific and harmful [s6]. Alun Williams, professor of sport and exercise genomics at Manchester Metropolitan University Institute of Sport, and Silvia Camporesi, professor of bioethics and sports integrity and ethics at KU Leuven, were among the authors [s6]. The editorial's central empirical claim is an absence: there is no robust evidence that the presence of SRY in a person with a difference in sex development directly correlates with an athletic performance advantage [s6]. It also raises concerns about coercive consent, medical privacy and the testing of minors [s6].

Williams made the same point more bluntly in a statement collected the day the IOC policy was announced: "There's no convincing direct evidence that athletes with DSDs have advantages in sport" [s7].

Not every expert reading is aligned. In the same collection, Ashley Grossman, emeritus professor of endocrinology at the University of Oxford, said "proceeding through male puberty provides a clear advantage in many physical sports", while distinguishing that case from athletes with differences in sex development and supporting the CAIS exemption [s7]. The disagreement, in other words, is not a single argument. Evidence about transgender women who have gone through male puberty and evidence about women with DSD conditions are different literatures, and the policy applies one screen to both groups.

The historical record

Sport has run genetic sex screening before, and the numbers from that period are instructive about base rates. A 2026 review in Frontiers in Sports and Active Living records that 2,406 women were tested at the 1992 Barcelona Olympics, of whom five returned positive results; at the 1996 Atlanta Games, 3,387 women were tested and eight returned positive results [s8]. The same review documents the case of María José Martínez Patiño, whose 1985 test identified her as 46,XY — later understood as androgen insensitivity — and ended her career [s8]. She is a co-author of the paper [s8].

The review also notes that in 2015 the Court of Arbitration for Sport suspended World Athletics' hyperandrogenism regulations, finding insufficient evidence linking elevated testosterone to a competitive advantage in female athletes [s8]. That ruling concerned hormone thresholds rather than gene screening, but it is the closest thing sport has to an adjudicated finding on the underlying performance question.

What to watch

Three things will determine how this plays out. First, whether the IOC publishes the scientific working group's reasoning and the performance evidence it relied on — the policy followed an 18-month consultation, but the underlying evidence base has not been laid out in the form the editorial's authors are asking for [s2][s6]. Second, whether national legal systems accommodate the screen: the French Olympic Committee has already flagged that SRY testing sits awkwardly with French bioethics law [s2]. Third, the practical question of what happens to athletes who screen positive and must then obtain, and disclose, a diagnosis to keep competing [s6].

None of this is settled. The claim that the test is accurate at detecting the gene and the claim that gene presence maps onto competitive advantage are separate claims, supported by very different amounts of evidence.

Sources

• [s1] Olympics Committee Bans Transgender Athletes From Women's Events — TIME, 26 March 2026
• [s2] Transgender women barred from female Olympic events — RTÉ News, 27 March 2026
• [s3] World Athletics introduces SRY gene test for athletes wishing to compete in the female category — World Athletics, 30 July 2025
• [s4] Seb Coe reveals SRY test receives 90 per cent uptake by athletes in female categories — Sky Sports, 29 August 2025
• [s5] IOC should not use SRY test to determine gender of women's athletes, says scientist who discovered it — ABC News (Australia), 31 March 2026
• [s6] Mandatory gene testing for female athletes is 'unscientific and harmful', say researchers — Manchester Metropolitan University, 5 March 2026
• [s7] Expert reaction to the IOC announcing new Policy on the Protection of the Female (Women's) Category in Olympic Sport — Science Media Centre, 26 March 2026
• [s8] Sex testing in women's sport: historical harms, contemporary risks, and World Athletics' 2025 policy shift — Frontiers in Sports and Active Living, 10 February 2026