OrientDB: http://orientdb.com/docs/last/Schema.html

OrientDB would indeed be an example of something that's only a "graph database" because marketing said it should be.

Last time I asked how to import an actual graph into OrientDB, a marketing person of theirs pointed me at a Java API for writing extensions to their code.

http://cancerhawk.com/navigator is a search tool to find local specialists for particular cancers types