Scientists have discovered what makes celebrity cat Lil Bub so extraordinary

She never developed teeth and each of her paws has an extra toe, for a total of 22.

The Washington Post
April 12, 2019 at 5:02AM
Provided photo of Lil Bub, the celebricat
Provided photo of Lil Bub, the celebricat (The Minnesota Star Tribune)

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.

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