Patient and Public Involvement in Research (PPIR) has become an increasingly prevalent and integral part of biomedical research. In this paper, we focus on patient-led research, taking as our case the construction of new biomedical knowledge regarding the rare disease ADNP syndrome. Specifically, we seek to understand how concepts of experiential knowledge and lay expertise become integral to rather than separate from scientific expertise. In the case of ADNP, the parent-led research "mimes" biomedical knowledge practices in a way that, on the one hand, enhances the legitimacy of science and scientific expertise, and on the other displaces and transforms science by the fact that other knowledge agents (patients, next-of-kin) enter these practices.
Keywords: biomedicine; citizen science; health activism; knowledge production; lay-scientist interactions; patient activism; patient advocacy; patient and public involvement.