Mondo.

The same disease has a dozen names, in a dozen databases, that do not agree.

Human disease knowledge is scattered across resources that each grew up on their own: OMIM for Mendelian disorders, Orphanet for rare disease, and many more. Each has its own identifiers, its own boundaries, its own way of splitting and lumping conditions. Ask them all the same question and you get answers that cannot be lined up, because no two of them mean exactly the same thing by the same word.

Mondo, built by the Monarch Initiative, is the effort to reconcile them. It merges those vocabularies into one logically consistent hierarchy, with the cross-references made explicit, so a disease has a single coherent identity and you can move between the source databases without losing your place. It is quiet, unglamorous infrastructure, the kind that makes everything built on top of it possible.

Mondo is how a dog's disease finds the human one it models.

A canine disease in Sniff comes from OMIA. When that disease has a human counterpart, Mondo is the map that connects the two, so the page can show the human analog with a coherent identity and a link back to the human literature. That connection is the whole of comparative medicine on Sniff: Degenerative Myelopathy in a dog read against the human ALS it models.

We are careful with the direction of that claim. The dog's disease is the subject; the human disease is the analog it models, never asserted to be it. Mondo gives us the coherent human identity to point at. The honesty of how we point is ours to keep.