@Imdunfer Ross Tucker (Scienceofsport on X) has raised the issue of PAIS / CAIS - how do you diagnose CAIS and not PAIS?
This was a series of Tweets from him on 28/3/26:
This is the burning question. Well, one of them. In Semenya CAS case, there was a discussion on this, and the experts were split. David Handelsman is a world leader on this and he was saying there is no advantage, that the condition is not over-represented in sport, and that conditions that have been seen more often in elite sport are 5-ARD and PAIS, but CAIS is not seen in sport, and that when you have skeletal differences, that's not CAIS, but rather PAIS. I've heard others argue that factors other than testosterone are responsible, so then CAIS would produce some male advantages. I must confess that i will need to investigate this in more detail to understand this split. But it feels to me that true CAIS will be very, very rare in sport, and the bigger challenge is going to be diagnosis, and not letting it become an explanation that people jump on too fast, as a kind of bypass of policies. Then you'll get PAIS being classified as CAIS and the policy will not be working as it should be. I think this is more of a problem than CAIS offering small advantages (which should be dealt with too!
And:
The thing I think sport hasn't done too well (those who have policies), is describe in detail how a CAIS decision is made. If you look at anti-doping, there are these crazy technical documents, with huge detail, on how tests are done. The same is needed for CAIS. I hope that is still coming, or at the very least, the default to the highest accepted standard in clinical settings. But they seem to have left a loophole large enough for doubt, and possibly large enough for exploitation. And a diagnosis based on visual inspection is not ideal. We are in a molecular age where the specific mutations in genes for those androgen receptors can be described, and compared to a library of known mutations, and then assays to test the effect of the mutation. I think that is needed, to give strength to the policy's exception.