97 Medical decision‑making competence regarding puberty suppression: perceptions of transgender adolescents, their parents and clinicians 5 “Especially those who have a disharmonic intelligence profile, who are verbally quite strong, but of whom you can wonder whether he/she is able to reason, and understand and appreciate the information [about the treatment and its (possible) consequences]. We do take more time for these cases [even though] we do not doubt the diagnosis [of gender dysphoria].” - Focus group with clinicians Furthermore, clinicians mentioned that the presence of (serious) mental health problems and/or other developmental (like autism spectrum disorder) or physical differences (like deafness) might affect the adolescent’s MDC. Some wondered how MDC should be assessed in those circumstances. “I think that, when you’re dealing with for example [someone with an] autism spectrum disorder, a deaf person, or someone with a very low intelligence, you have the idea that it almost becomes a black box; that you almost have to deduce the behaviour [of the adolescent] to have an idea of what is happening inside that black box and how plausible is it that the adolescent has ‘authentic’ gender dysphoria?” - Focus group with clinicians Relevance of medical decision-making competence Finally, one of the clinicians questioned why MDC to start PS is seen as such an important aspect to be eligible to start the treatment. The clinician wondered whether some people might assume that there is a direct correlation between MDC and the chance of having regrets about the decision to start the treatment later in life, even though competent adolescents who start PS may potentially still have regrets about this decision. “Why do we insist on medical decision-making competence, if it were about regret [of the treatment], could we argue that if it [what the treatment with puberty suppression and its (possible) consequences entails] has been discussed, it has become some kind of a deliberate choice, whichmakes it less likely you will regret it?” - Focus group with clinicians This theme did not feature in any of the interviews with the adolescents or the parents. DISCUSSION Using qualitative methods, this study aimed to explicate and compare the perceptions of transgender adolescents who had continued or discontinued PS, their parents, and clinicians regarding adolescent’s MDC to start PS. From thematic analysis three themes emerged, being: challenges when assessing MDC to start PS, aspects that are considered when assessing the adolescent’s MDC, and relevance of MDC.