Dario Lupianez is the author of dense scientific papers with titles including “Breaking TADs: How alterations of chromatin domains result in disease.” Now he, as part as one member of a team of molecular biologists, is also a co-author of a paper on the extraordinary genetics of celebrity cat Lil Bub.

Lil Bub is a kitten-size cat with 2 million Instagram followers, a talk show, a stage production, an album and a book. Bub has a short snout, enormous green eyes and a tongue that hangs from her stunted jaw. She never developed teeth and each of her paws has an extra toe, for a total of 22.

Lupianez, Daniel Ibrahim, a postdoctoral researcher at the Max Planck Institute for Molecular Genetics, and University of Pennsylvania’s Orsolya Symmons wondered whether the cat’s two conditions — polydactyly, the term for her extra digits, and the rare bone-hardening disorder osteopetrosis — might be the result of one gene mutation.

They found that Lil Bub’s polydactyly resulted from the same gene mutation that causes it in Ernest Hemingway’s famous six-toed cats, which means Bub is related to those cats. It also meant that “everything else that makes Bub so unique … is probably due to another mutation,” Ibrahim said.

That led them to a mutation in a gene called RANK/TNFRSF11A, which has been found in about 15 humans and one mouse. In X-rays, their bones look deformed and bright white, with little to no marrow cavity. What it all adds up to, the researchers said, is a new case study for an extremely rare disorder. That means that Lil Bub could help doctors better treat human patients whose osteopetrosis stems from the same gene mutation.