The rare, the common, the hope—including the excluded

Abstract Autosomal dominant polycystic kidney disease (ADPKD) occupies an ambiguous space that exposes the architecture of exclusion in rare disease policy. Prevalence estimates place it between 1 in 400 and 1 in 2500, hovering at the EU's rare-disease threshold, and its classification remains contested. Within the rare community it is the "common rare"; in policy it is the "excluded middle": too rare for large trials, too common for orphan-drug urgency, served fully by neither. This essay examines systematic exclusion from pivotal trials, revealing how legitimate clinical concerns are sustained by structural incentives that reward clean results over generalisable knowledge. It critiques the uneven health literacy burden that rare disease imposes, and exposes the invisibility of the undiagnosed, those excluded by eligibility criteria or limited resources, the outcomes patients value most, and the children rarely asked at all. It closes with a concrete charter: mandated evidence generation for excluded subgroups, accessible knowledge across literacy levels, recognition of the excluded middle as a distinct policy category, publishing truths beyond survival endpoints, and meaningful patient engagement in co-design, co-production and co-authorship. If journals become that infrastructure, the excluded middle becomes a bridge, not a blind spot.